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Attention-as-RNN

Non-Official Implementation of "Attention as an RNN" from https://arxiv.org/pdf/2405.13956 implemented as a recurrent layer and efficient prefix-sum layer.

Usage Example

import numpy as np 
from src import models,layers,utils 
import matplotlib.pyplot as plt 

EPOCHS = 400
BATCH_SIZE = 50

# Init sin dataset 
x = utils.generate_sin()
x = tf.transpose(x, (2, 0, 1))

# Init Model
model = models.ScanRNNAttentionModel(heads=[10, 5], dims=[5, 2], activation="silu", concat_heads=False)
_ = model(x)
model.compile("adam", "mse")
# Train 
history = model.fit(x, x, epochs=EPOCHS, batch_size=BATCH_SIZE)

# Visualize Result 
o = model(x)
plt.plot(o[30, :, 0], label="RNN-Attention")
plt.plot(x[30, :, 0], label="True")
plt.legend()

plt.plot(history.history["loss"], label="train loss")
plt.plot(history.history["val_loss"], label="validation loss")
plt.ylabel("Loss")
plt.xlabel("Epochs")
plt.legend()

You can also run the model in training mode, making the output stochasic via dropout and approximating the epistemic uncertainty

from src import plotter
fig, ax = plotter.plot_hist2d(scan_model, x[0], axis=0)

You can train the model using the pre-fix sum implementation and transfer the weights to the recurrent implementation to make inference recurrentely:

config = model.get_config()
heads = config["heads"]
dims = config["dims"]
activation = config["activation"]
dropout = config["dropout"]
recurrent_dropout = config["recurrent_dropout"]

rnn_model = models.AttentionRNN(
    heads,
    dims,
    activation=activation,
    dropout=dropout,
    recurrent_dropout=recurrent_dropout,
)
rnn_model.build(x.shape)
rnn_model.set_weights(scan_model.get_weights())
rnn_model.compile("adam", "mse")

Tensorboard Step-Time Graph

Time Series Classification

# Load dataset (!pip install aeon)
from aeon.datasets import load_classification
X, y = load_classification("ECG200")
y = y.astype(float)
y = np.where(y>0, 1., 0.)

plt.plot(X[:10, 0, :].T)

ScanAttention Model (69% accuracy)

# Construct model 
ki = tf.keras.Input(shape=(None, 1))
scan = models.ScanRNNAttentionModel([10, 10], [10, 10])
avg_pool = tf.keras.layers.GlobalAveragePooling1D()
max_pool = tf.keras.layers.GlobalMaxPooling1D()
min_pool = tf.keras.layers.Lambda(lambda x: tf.reduce_min(x, -2))
conc = tf.keras.layers.Concatenate()
dense = tf.keras.layers.Dense(1, "sigmoid")

h = scan(ki)
avgp = avg_pool(h)
maxp = max_pool(h)
minp = min_pool(h)
mix = conc([avgp, maxp, minp])
o = dense(mix)

classification_model = tf.keras.Model(ki, o)
classification_model.compile("adam", "bce")

# Train
hist = classification_model.fit(X[:, 0, :], y, epochs=1000)

# Score
pred = classification_model.predict(X[:, 0, :])
tf.keras.metrics.Accuracy()(pred>0.5, y)

LinearSelfAttention Model (74% accuracy)

ki = tf.keras.Input(shape=(None, 1))

cnn = layers.LinearSelfAttention(5,10, "linear")
avg_pool = tf.keras.layers.GlobalAveragePooling1D()
max_pool = tf.keras.layers.GlobalMaxPooling1D()
min_pool = tf.keras.layers.Lambda(lambda x: tf.reduce_min(x, -2))
conc = tf.keras.layers.Concatenate()
dense = tf.keras.layers.Dense(1, "sigmoid")

h = cnn(ki)
avgp = avg_pool(h)
maxp = max_pool(h)
minp = min_pool(h)
mix = conc([avgp, maxp, minp])
o = dense(mix)

classification_model_linear = tf.keras.Model(ki, o)
classification_model_linear.compile("adam", "bce")

CNN1D Model (97% accuracy)

ki = tf.keras.Input(shape=(None, 1))

cnn = tf.keras.layers.Conv1D(32,10)
avg_pool = tf.keras.layers.GlobalAveragePooling1D()
max_pool = tf.keras.layers.GlobalMaxPooling1D()
min_pool = tf.keras.layers.Lambda(lambda x: tf.reduce_min(x, -2))
conc = tf.keras.layers.Concatenate()
dense = tf.keras.layers.Dense(1, "sigmoid")

h = cnn(ki)
avgp = avg_pool(h)
maxp = max_pool(h)
minp = min_pool(h)
mix = conc([avgp, maxp, minp])
o = dense(mix)

classification_model_cnn = tf.keras.Model(ki, o)
classification_model_cnn.compile("adam", "bce")