100_Numpy_exercises.ipynb

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        "<a href=\"https://colab.research.google.com/github/izumis007/numpy-100/blob/master/100_Numpy_exercises.ipynb\" target=\"_parent\"><img src=\"https://colab.research.google.com/assets/colab-badge.svg\" alt=\"Open In Colab\"/></a>"
      ]
    },
    {
      "cell_type": "markdown",
      "id": "f44a2f2b",
      "metadata": {
        "id": "f44a2f2b"
      },
      "source": [
        "# 100 numpy exercises\n",
        "\n",
        "This is a collection of exercises that have been collected in the numpy mailing list, on stack overflow\n",
        "and in the numpy documentation. The goal of this collection is to offer a quick reference for both old\n",
        "and new users but also to provide a set of exercises for those who teach.\n",
        "\n",
        "\n",
        "If you find an error or think you've a better way to solve some of them, feel\n",
        "free to open an issue at <https://github.com/rougier/numpy-100>."
      ]
    },
    {
      "cell_type": "markdown",
      "id": "0fe3d529",
      "metadata": {
        "id": "0fe3d529"
      },
      "source": [
        "File automatically generated. See the documentation to update questions/answers/hints programmatically."
      ]
    },
    {
      "cell_type": "markdown",
      "id": "23296a93",
      "metadata": {
        "id": "23296a93"
      },
      "source": [
        "Run the `initialize.py` module, then for each question you can query the\n",
        "answer or an hint with `hint(n)` or `answer(n)` for `n` question number."
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 1,
      "id": "530390cf",
      "metadata": {
        "colab": {
          "base_uri": "https://localhost:8080/"
        },
        "id": "530390cf",
        "outputId": "7d132a31-775c-49af-a90a-4e66e7ef3598"
      },
      "outputs": [
        {
          "output_type": "stream",
          "name": "stderr",
          "text": [
            "ERROR:root:File `'initialise.py'` not found.\n"
          ]
        }
      ],
      "source": [
        "%run initialise.py"
      ]
    },
    {
      "cell_type": "markdown",
      "id": "96443564",
      "metadata": {
        "id": "96443564"
      },
      "source": [
        "#### 1. Import the numpy package under the name `np` (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 3,
      "id": "ffe1047e",
      "metadata": {
        "id": "ffe1047e"
      },
      "outputs": [],
      "source": [
        "import numpy as np"
      ]
    },
    {
      "cell_type": "markdown",
      "id": "c807bf1d",
      "metadata": {
        "id": "c807bf1d"
      },
      "source": [
        "#### 2. Print the numpy version and the configuration (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "f396b717",
      "metadata": {
        "id": "f396b717"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "572c1bdb",
      "metadata": {
        "id": "572c1bdb"
      },
      "source": [
        "#### 3. Create a null vector of size 10 (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "31c9f6a5",
      "metadata": {
        "id": "31c9f6a5"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "337e6e36",
      "metadata": {
        "id": "337e6e36"
      },
      "source": [
        "#### 4. How to find the memory size of any array (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "31e8ec2e",
      "metadata": {
        "id": "31e8ec2e"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "166079c8",
      "metadata": {
        "id": "166079c8"
      },
      "source": [
        "#### 5. How to get the documentation of the numpy add function from the command line? (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "593cd80f",
      "metadata": {
        "id": "593cd80f"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "3add7101",
      "metadata": {
        "id": "3add7101"
      },
      "source": [
        "#### 6. Create a null vector of size 10 but the fifth value which is 1 (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "2edf3c42",
      "metadata": {
        "id": "2edf3c42"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "cfc46304",
      "metadata": {
        "id": "cfc46304"
      },
      "source": [
        "#### 7. Create a vector with values ranging from 10 to 49 (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "d8b86640",
      "metadata": {
        "id": "d8b86640"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "0cc200be",
      "metadata": {
        "id": "0cc200be"
      },
      "source": [
        "#### 8. Reverse a vector (first element becomes last) (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "ec044bb5",
      "metadata": {
        "id": "ec044bb5"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "29d9ede4",
      "metadata": {
        "id": "29d9ede4"
      },
      "source": [
        "#### 9. Create a 3x3 matrix with values ranging from 0 to 8 (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "d9e39043",
      "metadata": {
        "id": "d9e39043"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "88905ceb",
      "metadata": {
        "id": "88905ceb"
      },
      "source": [
        "#### 10. Find indices of non-zero elements from [1,2,0,0,4,0] (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "b2f3c90a",
      "metadata": {
        "id": "b2f3c90a"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "49603e91",
      "metadata": {
        "id": "49603e91"
      },
      "source": [
        "#### 11. Create a 3x3 identity matrix (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "5b607b5c",
      "metadata": {
        "id": "5b607b5c"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "e15c249a",
      "metadata": {
        "id": "e15c249a"
      },
      "source": [
        "#### 12. Create a 3x3x3 array with random values (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "ab21ed50",
      "metadata": {
        "id": "ab21ed50"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "157a129c",
      "metadata": {
        "id": "157a129c"
      },
      "source": [
        "#### 13. Create a 10x10 array with random values and find the minimum and maximum values (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "c0066de5",
      "metadata": {
        "id": "c0066de5"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "d92d7b32",
      "metadata": {
        "id": "d92d7b32"
      },
      "source": [
        "#### 14. Create a random vector of size 30 and find the mean value (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "9672d023",
      "metadata": {
        "id": "9672d023"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "f361efc0",
      "metadata": {
        "id": "f361efc0"
      },
      "source": [
        "#### 15. Create a 2d array with 1 on the border and 0 inside (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "a55b6666",
      "metadata": {
        "id": "a55b6666"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "475808cb",
      "metadata": {
        "id": "475808cb"
      },
      "source": [
        "#### 16. How to add a border (filled with 0's) around an existing array? (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "b2df3a8a",
      "metadata": {
        "id": "b2df3a8a"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "1af07d85",
      "metadata": {
        "id": "1af07d85"
      },
      "source": [
        "#### 17. What is the result of the following expression? (★☆☆)\n",
        "```python\n",
        "0 * np.nan\n",
        "np.nan == np.nan\n",
        "np.inf > np.nan\n",
        "np.nan - np.nan\n",
        "np.nan in set([np.nan])\n",
        "0.3 == 3 * 0.1\n",
        "```"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "109cf327",
      "metadata": {
        "id": "109cf327"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "6a235316",
      "metadata": {
        "id": "6a235316"
      },
      "source": [
        "#### 18. Create a 5x5 matrix with values 1,2,3,4 just below the diagonal (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "f2e6cfa6",
      "metadata": {
        "id": "f2e6cfa6"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "25362e98",
      "metadata": {
        "id": "25362e98"
      },
      "source": [
        "#### 19. Create a 8x8 matrix and fill it with a checkerboard pattern (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "cabdf298",
      "metadata": {
        "id": "cabdf298"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "6431e977",
      "metadata": {
        "id": "6431e977"
      },
      "source": [
        "#### 20. Consider a (6,7,8) shape array, what is the index (x,y,z) of the 100th element? (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "de8b0245",
      "metadata": {
        "id": "de8b0245"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "31abe6fe",
      "metadata": {
        "id": "31abe6fe"
      },
      "source": [
        "#### 21. Create a checkerboard 8x8 matrix using the tile function (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "6da26fd3",
      "metadata": {
        "id": "6da26fd3"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "fd88b3f4",
      "metadata": {
        "id": "fd88b3f4"
      },
      "source": [
        "#### 22. Normalize a 5x5 random matrix (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "ee6ced60",
      "metadata": {
        "id": "ee6ced60"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "464d8590",
      "metadata": {
        "id": "464d8590"
      },
      "source": [
        "#### 23. Create a custom dtype that describes a color as four unsigned bytes (RGBA) (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "e2f9cfc6",
      "metadata": {
        "id": "e2f9cfc6"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "06c63bb3",
      "metadata": {
        "id": "06c63bb3"
      },
      "source": [
        "#### 24. Multiply a 5x3 matrix by a 3x2 matrix (real matrix product) (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "9fc0d553",
      "metadata": {
        "id": "9fc0d553"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "76fa6285",
      "metadata": {
        "id": "76fa6285"
      },
      "source": [
        "#### 25. Given a 1D array, negate all elements which are between 3 and 8, in place. (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "0e25eca7",
      "metadata": {
        "id": "0e25eca7"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "930ed8bb",
      "metadata": {
        "id": "930ed8bb"
      },
      "source": [
        "#### 26. What is the output of the following script? (★☆☆)\n",
        "```python\n",
        "# Author: Jake VanderPlas\n",
        "\n",
        "print(sum(range(5),-1))\n",
        "from numpy import *\n",
        "print(sum(range(5),-1))\n",
        "```"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "f02eedba",
      "metadata": {
        "id": "f02eedba"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "177120e7",
      "metadata": {
        "id": "177120e7"
      },
      "source": [
        "#### 27. Consider an integer vector Z, which of these expressions are legal? (★☆☆)\n",
        "```python\n",
        "Z**Z\n",
        "2 << Z >> 2\n",
        "Z <- Z\n",
        "1j*Z\n",
        "Z/1/1\n",
        "Z<Z>Z\n",
        "```"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "86d6cbef",
      "metadata": {
        "id": "86d6cbef"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "a6eaf0e8",
      "metadata": {
        "id": "a6eaf0e8"
      },
      "source": [
        "#### 28. What are the result of the following expressions? (★☆☆)\n",
        "```python\n",
        "np.array(0) / np.array(0)\n",
        "np.array(0) // np.array(0)\n",
        "np.array([np.nan]).astype(int).astype(float)\n",
        "```"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "93684068",
      "metadata": {
        "id": "93684068"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "524b65f8",
      "metadata": {
        "id": "524b65f8"
      },
      "source": [
        "#### 29. How to round away from zero a float array ? (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "61fbb78e",
      "metadata": {
        "id": "61fbb78e"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "8dc40752",
      "metadata": {
        "id": "8dc40752"
      },
      "source": [
        "#### 30. How to find common values between two arrays? (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "54399cbe",
      "metadata": {
        "id": "54399cbe"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "b7f38e21",
      "metadata": {
        "id": "b7f38e21"
      },
      "source": [
        "#### 31. How to ignore all numpy warnings (not recommended)? (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "2ca3289c",
      "metadata": {
        "id": "2ca3289c"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "2d850aab",
      "metadata": {
        "id": "2d850aab"
      },
      "source": [
        "#### 32. Is the following expressions true? (★☆☆)\n",
        "```python\n",
        "np.sqrt(-1) == np.emath.sqrt(-1)\n",
        "```"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "5c83ffce",
      "metadata": {
        "id": "5c83ffce"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "5c4a556f",
      "metadata": {
        "id": "5c4a556f"
      },
      "source": [
        "#### 33. How to get the dates of yesterday, today and tomorrow? (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "c3b683a0",
      "metadata": {
        "id": "c3b683a0"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "453cdd64",
      "metadata": {
        "id": "453cdd64"
      },
      "source": [
        "#### 34. How to get all the dates corresponding to the month of July 2016? (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "4ba4d37c",
      "metadata": {
        "id": "4ba4d37c"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "52667b6e",
      "metadata": {
        "id": "52667b6e"
      },
      "source": [
        "#### 35. How to compute ((A+B)*(-A/2)) in place (without copy)? (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "e6e7c030",
      "metadata": {
        "id": "e6e7c030"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "9a8f3738",
      "metadata": {
        "id": "9a8f3738"
      },
      "source": [
        "#### 36. Extract the integer part of a random array of positive numbers using 4 different methods (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "368a801a",
      "metadata": {
        "id": "368a801a"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "cab1eed1",
      "metadata": {
        "id": "cab1eed1"
      },
      "source": [
        "#### 37. Create a 5x5 matrix with row values ranging from 0 to 4 (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "f1b579ba",
      "metadata": {
        "id": "f1b579ba"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "cd0ce6b1",
      "metadata": {
        "id": "cd0ce6b1"
      },
      "source": [
        "#### 38. Consider a generator function that generates 10 integers and use it to build an array (★☆☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "aab193a6",
      "metadata": {
        "id": "aab193a6"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "c4c942d1",
      "metadata": {
        "id": "c4c942d1"
      },
      "source": [
        "#### 39. Create a vector of size 10 with values ranging from 0 to 1, both excluded (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "e42eaa4b",
      "metadata": {
        "id": "e42eaa4b"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "9b3cb8d2",
      "metadata": {
        "id": "9b3cb8d2"
      },
      "source": [
        "#### 40. Create a random vector of size 10 and sort it (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "37d2b341",
      "metadata": {
        "id": "37d2b341"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "2facfddc",
      "metadata": {
        "id": "2facfddc"
      },
      "source": [
        "#### 41. How to sum a small array faster than np.sum? (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "4bb8864f",
      "metadata": {
        "id": "4bb8864f"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "539cd2a5",
      "metadata": {
        "id": "539cd2a5"
      },
      "source": [
        "#### 42. Consider two random array A and B, check if they are equal (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "5246d7bf",
      "metadata": {
        "id": "5246d7bf"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "448f8274",
      "metadata": {
        "id": "448f8274"
      },
      "source": [
        "#### 43. Make an array immutable (read-only) (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "7cf2b3dd",
      "metadata": {
        "id": "7cf2b3dd"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "d7b7aaf3",
      "metadata": {
        "id": "d7b7aaf3"
      },
      "source": [
        "#### 44. Consider a random 10x2 matrix representing cartesian coordinates, convert them to polar coordinates (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "e2337585",
      "metadata": {
        "id": "e2337585"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "a556027a",
      "metadata": {
        "id": "a556027a"
      },
      "source": [
        "#### 45. Create random vector of size 10 and replace the maximum value by 0 (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "9e07cb87",
      "metadata": {
        "id": "9e07cb87"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "004f3da1",
      "metadata": {
        "id": "004f3da1"
      },
      "source": [
        "#### 46. Create a structured array with `x` and `y` coordinates covering the [0,1]x[0,1] area (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "b3824741",
      "metadata": {
        "id": "b3824741"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "1c0adc0d",
      "metadata": {
        "id": "1c0adc0d"
      },
      "source": [
        "#### 47. Given two arrays, X and Y, construct the Cauchy matrix C (Cij =1/(xi - yj)) (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "01b3bbb7",
      "metadata": {
        "id": "01b3bbb7"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "c8a2f65a",
      "metadata": {
        "id": "c8a2f65a"
      },
      "source": [
        "#### 48. Print the minimum and maximum representable value for each numpy scalar type (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "35d844d6",
      "metadata": {
        "id": "35d844d6"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "11727a69",
      "metadata": {
        "id": "11727a69"
      },
      "source": [
        "#### 49. How to print all the values of an array? (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "47e98473",
      "metadata": {
        "id": "47e98473"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "e0e7d741",
      "metadata": {
        "id": "e0e7d741"
      },
      "source": [
        "#### 50. How to find the closest value (to a given scalar) in a vector? (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "62cabf6f",
      "metadata": {
        "id": "62cabf6f"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "c5611b9e",
      "metadata": {
        "id": "c5611b9e"
      },
      "source": [
        "#### 51. Create a structured array representing a position (x,y) and a color (r,g,b) (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "f622939d",
      "metadata": {
        "id": "f622939d"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "d22b8574",
      "metadata": {
        "id": "d22b8574"
      },
      "source": [
        "#### 52. Consider a random vector with shape (100,2) representing coordinates, find point by point distances (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "d5c9cdf8",
      "metadata": {
        "id": "d5c9cdf8"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "f5c164f2",
      "metadata": {
        "id": "f5c164f2"
      },
      "source": [
        "#### 53. How to convert a float (32 bits) array into an integer (32 bits) in place?"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "ea262de8",
      "metadata": {
        "id": "ea262de8"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "a8b7e6f5",
      "metadata": {
        "id": "a8b7e6f5"
      },
      "source": [
        "#### 54. How to read the following file? (★★☆)\n",
        "```\n",
        "1, 2, 3, 4, 5\n",
        "6,  ,  , 7, 8\n",
        " ,  , 9,10,11\n",
        "```"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "bde0538a",
      "metadata": {
        "id": "bde0538a"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "c6b32834",
      "metadata": {
        "id": "c6b32834"
      },
      "source": [
        "#### 55. What is the equivalent of enumerate for numpy arrays? (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "ab02472a",
      "metadata": {
        "id": "ab02472a"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "a2121a05",
      "metadata": {
        "id": "a2121a05"
      },
      "source": [
        "#### 56. Generate a generic 2D Gaussian-like array (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "18507102",
      "metadata": {
        "id": "18507102"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "97055efa",
      "metadata": {
        "id": "97055efa"
      },
      "source": [
        "#### 57. How to randomly place p elements in a 2D array? (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "292e842f",
      "metadata": {
        "id": "292e842f"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "bfd2513c",
      "metadata": {
        "id": "bfd2513c"
      },
      "source": [
        "#### 58. Subtract the mean of each row of a matrix (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "f306ab72",
      "metadata": {
        "id": "f306ab72"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "da9f2f9b",
      "metadata": {
        "id": "da9f2f9b"
      },
      "source": [
        "#### 59. How to sort an array by the nth column? (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "68cde57f",
      "metadata": {
        "id": "68cde57f"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "5b7be45c",
      "metadata": {
        "id": "5b7be45c"
      },
      "source": [
        "#### 60. How to tell if a given 2D array has null columns? (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "7dbe2c27",
      "metadata": {
        "id": "7dbe2c27"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "7c18c02e",
      "metadata": {
        "id": "7c18c02e"
      },
      "source": [
        "#### 61. Find the nearest value from a given value in an array (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "b78ae9c4",
      "metadata": {
        "id": "b78ae9c4"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "8174ba2c",
      "metadata": {
        "id": "8174ba2c"
      },
      "source": [
        "#### 62. Considering two arrays with shape (1,3) and (3,1), how to compute their sum using an iterator? (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "8a18fe57",
      "metadata": {
        "id": "8a18fe57"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "9189bd7c",
      "metadata": {
        "id": "9189bd7c"
      },
      "source": [
        "#### 63. Create an array class that has a name attribute (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "1c01ed42",
      "metadata": {
        "id": "1c01ed42"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "f30162d2",
      "metadata": {
        "id": "f30162d2"
      },
      "source": [
        "#### 64. Consider a given vector, how to add 1 to each element indexed by a second vector (be careful with repeated indices)? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "093ba36f",
      "metadata": {
        "id": "093ba36f"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "f5b1c584",
      "metadata": {
        "id": "f5b1c584"
      },
      "source": [
        "#### 65. How to accumulate elements of a vector (X) to an array (F) based on an index list (I)? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "c9d92a75",
      "metadata": {
        "id": "c9d92a75"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "994c452d",
      "metadata": {
        "id": "994c452d"
      },
      "source": [
        "#### 66. Considering a (w,h,3) image of (dtype=ubyte), compute the number of unique colors (★★☆)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "269cdaea",
      "metadata": {
        "id": "269cdaea"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "4bddeb31",
      "metadata": {
        "id": "4bddeb31"
      },
      "source": [
        "#### 67. Considering a four dimensions array, how to get sum over the last two axis at once? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "32af15f5",
      "metadata": {
        "id": "32af15f5"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "c4cf083c",
      "metadata": {
        "id": "c4cf083c"
      },
      "source": [
        "#### 68. Considering a one-dimensional vector D, how to compute means of subsets of D using a vector S of same size describing subset  indices? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "9600a2dd",
      "metadata": {
        "id": "9600a2dd"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "a5e316db",
      "metadata": {
        "id": "a5e316db"
      },
      "source": [
        "#### 69. How to get the diagonal of a dot product? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "94735dbd",
      "metadata": {
        "id": "94735dbd"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "de727a7b",
      "metadata": {
        "id": "de727a7b"
      },
      "source": [
        "#### 70. Consider the vector [1, 2, 3, 4, 5], how to build a new vector with 3 consecutive zeros interleaved between each value? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "982be812",
      "metadata": {
        "id": "982be812"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "a9a73d6b",
      "metadata": {
        "id": "a9a73d6b"
      },
      "source": [
        "#### 71. Consider an array of dimension (5,5,3), how to mulitply it by an array with dimensions (5,5)? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "282a90cc",
      "metadata": {
        "id": "282a90cc"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "a951c78f",
      "metadata": {
        "id": "a951c78f"
      },
      "source": [
        "#### 72. How to swap two rows of an array? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "e29b3fde",
      "metadata": {
        "id": "e29b3fde"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "43b639e8",
      "metadata": {
        "id": "43b639e8"
      },
      "source": [
        "#### 73. Consider a set of 10 triplets describing 10 triangles (with shared vertices), find the set of unique line segments composing all the  triangles (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "147e1034",
      "metadata": {
        "id": "147e1034"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "d41de585",
      "metadata": {
        "id": "d41de585"
      },
      "source": [
        "#### 74. Given a sorted array C that corresponds to a bincount, how to produce an array A such that np.bincount(A) == C? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "5f5d6e36",
      "metadata": {
        "id": "5f5d6e36"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "b50adf7c",
      "metadata": {
        "id": "b50adf7c"
      },
      "source": [
        "#### 75. How to compute averages using a sliding window over an array? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "e631a9d2",
      "metadata": {
        "id": "e631a9d2"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "1ab4c50d",
      "metadata": {
        "id": "1ab4c50d"
      },
      "source": [
        "#### 76. Consider a one-dimensional array Z, build a two-dimensional array whose first row is (Z[0],Z[1],Z[2]) and each subsequent row is  shifted by 1 (last row should be (Z[-3],Z[-2],Z[-1]) (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "3ccfe2c0",
      "metadata": {
        "id": "3ccfe2c0"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "5b4fe59d",
      "metadata": {
        "id": "5b4fe59d"
      },
      "source": [
        "#### 77. How to negate a boolean, or to change the sign of a float inplace? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "3c2373ff",
      "metadata": {
        "id": "3c2373ff"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "119ab5af",
      "metadata": {
        "id": "119ab5af"
      },
      "source": [
        "#### 78. Consider 2 sets of points P0,P1 describing lines (2d) and a point p, how to compute distance from p to each line i (P0[i],P1[i])? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "1d8d06dc",
      "metadata": {
        "id": "1d8d06dc"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "e5e7f323",
      "metadata": {
        "id": "e5e7f323"
      },
      "source": [
        "#### 79. Consider 2 sets of points P0,P1 describing lines (2d) and a set of points P, how to compute distance from each point j (P[j]) to each line i (P0[i],P1[i])? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "d0ce77e2",
      "metadata": {
        "id": "d0ce77e2"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "9b9d03eb",
      "metadata": {
        "id": "9b9d03eb"
      },
      "source": [
        "#### 80. Consider an arbitrary array, write a function that extract a subpart with a fixed shape and centered on a given element (pad with a `fill` value when necessary) (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "ec2b7ae3",
      "metadata": {
        "id": "ec2b7ae3"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "27794913",
      "metadata": {
        "id": "27794913"
      },
      "source": [
        "#### 81. Consider an array Z = [1,2,3,4,5,6,7,8,9,10,11,12,13,14], how to generate an array R = [[1,2,3,4], [2,3,4,5], [3,4,5,6], ..., [11,12,13,14]]? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "f3e7878b",
      "metadata": {
        "id": "f3e7878b"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "fae786f5",
      "metadata": {
        "id": "fae786f5"
      },
      "source": [
        "#### 82. Compute a matrix rank (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "64b9615b",
      "metadata": {
        "id": "64b9615b"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "c85aa0b9",
      "metadata": {
        "id": "c85aa0b9"
      },
      "source": [
        "#### 83. How to find the most frequent value in an array?"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "056be85b",
      "metadata": {
        "id": "056be85b"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "0ff2344d",
      "metadata": {
        "id": "0ff2344d"
      },
      "source": [
        "#### 84. Extract all the contiguous 3x3 blocks from a random 10x10 matrix (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "d58b1318",
      "metadata": {
        "id": "d58b1318"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "1a18b263",
      "metadata": {
        "id": "1a18b263"
      },
      "source": [
        "#### 85. Create a 2D array subclass such that Z[i,j] == Z[j,i] (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "87f17adc",
      "metadata": {
        "id": "87f17adc"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "f85f2cad",
      "metadata": {
        "id": "f85f2cad"
      },
      "source": [
        "#### 86. Consider a set of p matrices wich shape (n,n) and a set of p vectors with shape (n,1). How to compute the sum of of the p matrix products at once? (result has shape (n,1)) (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "8d230557",
      "metadata": {
        "id": "8d230557"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "5afb72c8",
      "metadata": {
        "id": "5afb72c8"
      },
      "source": [
        "#### 87. Consider a 16x16 array, how to get the block-sum (block size is 4x4)? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "e86f47a9",
      "metadata": {
        "id": "e86f47a9"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "6094d37c",
      "metadata": {
        "id": "6094d37c"
      },
      "source": [
        "#### 88. How to implement the Game of Life using numpy arrays? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "a93e715f",
      "metadata": {
        "id": "a93e715f"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "a173cf96",
      "metadata": {
        "id": "a173cf96"
      },
      "source": [
        "#### 89. How to get the n largest values of an array (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "b7c2ff35",
      "metadata": {
        "id": "b7c2ff35"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "15db2d01",
      "metadata": {
        "id": "15db2d01"
      },
      "source": [
        "#### 90. Given an arbitrary number of vectors, build the cartesian product (every combinations of every item) (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "a9a4633d",
      "metadata": {
        "id": "a9a4633d"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "5d94d1ef",
      "metadata": {
        "id": "5d94d1ef"
      },
      "source": [
        "#### 91. How to create a record array from a regular array? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "b1dae380",
      "metadata": {
        "id": "b1dae380"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "114ccc36",
      "metadata": {
        "id": "114ccc36"
      },
      "source": [
        "#### 92. Consider a large vector Z, compute Z to the power of 3 using 3 different methods (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "877c65d6",
      "metadata": {
        "id": "877c65d6"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "d614fee4",
      "metadata": {
        "id": "d614fee4"
      },
      "source": [
        "#### 93. Consider two arrays A and B of shape (8,3) and (2,2). How to find rows of A that contain elements of each row of B regardless of the order of the elements in B? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "e6807a84",
      "metadata": {
        "id": "e6807a84"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "b0eedca6",
      "metadata": {
        "id": "b0eedca6"
      },
      "source": [
        "#### 94. Considering a 10x3 matrix, extract rows with unequal values (e.g. [2,2,3]) (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "fc136ce2",
      "metadata": {
        "id": "fc136ce2"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "a65ec1cf",
      "metadata": {
        "id": "a65ec1cf"
      },
      "source": [
        "#### 95. Convert a vector of ints into a matrix binary representation (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "323cdf4c",
      "metadata": {
        "id": "323cdf4c"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "75b9397f",
      "metadata": {
        "id": "75b9397f"
      },
      "source": [
        "#### 96. Given a two dimensional array, how to extract unique rows? (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "9bb56a47",
      "metadata": {
        "id": "9bb56a47"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "82aaf21b",
      "metadata": {
        "id": "82aaf21b"
      },
      "source": [
        "#### 97. Considering 2 vectors A & B, write the einsum equivalent of inner, outer, sum, and mul function (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "cedcefd9",
      "metadata": {
        "id": "cedcefd9"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "7741e17f",
      "metadata": {
        "id": "7741e17f"
      },
      "source": [
        "#### 98. Considering a path described by two vectors (X,Y), how to sample it using equidistant samples (★★★)?"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "0b2432fe",
      "metadata": {
        "id": "0b2432fe"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "340d6f36",
      "metadata": {
        "id": "340d6f36"
      },
      "source": [
        "#### 99. Given an integer n and a 2D array X, select from X the rows which can be interpreted as draws from a multinomial distribution with n degrees, i.e., the rows which only contain integers and which sum to n. (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "a75323ae",
      "metadata": {
        "id": "a75323ae"
      },
      "outputs": [],
      "source": []
    },
    {
      "cell_type": "markdown",
      "id": "19721849",
      "metadata": {
        "id": "19721849"
      },
      "source": [
        "#### 100. Compute bootstrapped 95% confidence intervals for the mean of a 1D array X (i.e., resample the elements of an array with replacement N times, compute the mean of each sample, and then compute percentiles over the means). (★★★)"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "id": "87309c6f",
      "metadata": {
        "id": "87309c6f"
      },
      "outputs": [],
      "source": []
    }
  ],
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    },
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    },
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      "name": "python3",
      "display_name": "Python 3"
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