Merge pull request #52 from spsanderson/development

Fixes #34

NAMESPACE

@@ -11,6 +11,7 @@ export(csd)
 export(cskewness)
 export(cvar)
 export(discrete_walk)
+export(euclidean_distance)
 export(geometric_brownian_motion)
 export(kurtosis_vec)
 export(rand_walk_helper)

NEWS.md

@@ -13,6 +13,8 @@ None
 7. Fix #43 - Add vectorized functions
 8. Fix #44 - Add Function `internal_rand_walk_helper()` to help generate common
 columns for random walks.
+9. Fix #34 - Add Function `euclidean_distance()` to calculate the Euclidean distance
+of a random walk.
 
 ## Minor Improvements and Fixes
 None

R/vec-distance.R

@@ -0,0 +1,56 @@
+#' Distance Calculations
+#'
+#' @family Vector Function
+#'
+#' @author Steven P. Sanderson II, MPH
+#'
+#' @details
+#' A function to calculate the Euclidean distance between two vectors. It uses
+#' the formula `sqrt((x - lag(x))^2 + (y - lag(y))^2)`. The function uses augments
+#' the data frame with a new column called `distance`.
+#'
+#' @description
+#' A function to calculate the Euclidean distance between two vectors.
+#'
+#' @param .data A data frame
+#' @param .x A numeric vector
+#' @param .y A numeric vector
+#' @param .pull_vector A boolean of TRUE or FALSE. Default is FALSE which will
+#' augment the distance to the data frame. TRUE will return a vector of the distances
+#' as the return.
+#'
+#' @examples
+#' set.seed(123)
+#' df <- rw30()
+#' euclidean_distance(df, x, y)
+#' euclidean_distance(df, x, y, TRUE) |> head(10)
+#'
+#' @return
+#' A numeric Vector of ditances
+#'
+#' @name euclidean_distance
+NULL
+#' @rdname euclidean_distance
+#' @export
+
+euclidean_distance <- function(.data, .x, .y, .pull_vector = FALSE) {
+
+  # Tidyeval ---
+  x_var <- rlang::enquo(.x)
+  y_var <- rlang::enquo(.y)
+
+  # Calculate the distance ---
+  ret <- dplyr::as_tibble(.data) |>
+    dplyr::mutate(
+      distance = sqrt(
+        (!!x_var - dplyr::lag(!!x_var, 1))^2 + (!!y_var - dplyr::lag(!!y_var, 1))^2
+      )
+    )
+
+  # Return the distance vector ---
+  if (.pull_vector) {
+    return(ret[["distance"]])
+  }
+
+  return(ret)
+}

docs/pkgdown.yml

@@ -3,7 +3,7 @@ pkgdown: 2.1.0
 pkgdown_sha: ~
 articles:
   getting-started: getting-started.html
-last_built: 2024-07-29T19:09Z
+last_built: 2024-07-29T20:03Z
 urls:
   reference: https://www.spsanderson.com/RandomWalker/reference
   article: https://www.spsanderson.com/RandomWalker/articles