I would like to know how to add metrics like accuracy,precision and save model to this tensorboard logistic regression:
from tensorflow.keras.datasets import fashion_mnist
from sklearn.model_selection import train_test_split
import tensorflow as tf
(x_train, y_train), (x_test, y_test) = fashion_mnist.load_data()
x_train, x_test = x_train/255., x_test/255.
x_train, x_val, y_train, y_val = train_test_split(x_train, y_train, test_size=0.15)
x_train = tf.reshape(x_train, shape=(-1, 784))
x_test = tf.reshape(x_test, shape=(-1, 784))
weights = tf.Variable(tf.random.normal(shape=(784, 10), dtype=tf.float64))
biases = tf.Variable(tf.random.normal(shape=(10,), dtype=tf.float64))
def logistic_regression(x):
lr = tf.add(tf.matmul(x, weights), biases)
#return tf.nn.sigmoid(lr)
return lr
def cross_entropy(y_true, y_pred):
y_true = tf.one_hot(y_true, 10)
loss = tf.nn.softmax_cross_entropy_with_logits(labels=y_true, logits=y_pred)
return tf.reduce_mean(loss)
def accuracy(y_true, y_pred):
y_true = tf.cast(y_true, dtype=tf.int32)
preds = tf.cast(tf.argmax(y_pred, axis=1), dtype=tf.int32)
preds = tf.equal(y_true, preds)
return tf.reduce_mean(tf.cast(preds, dtype=tf.float32))
def grad(x, y):
with tf.GradientTape() as tape:
y_pred = logistic_regression(x)
loss_val = cross_entropy(y, y_pred)
return tape.gradient(loss_val, [weights, biases])
n_batches = 10000
learning_rate = 0.01
batch_size = 128
dataset = tf.data.Dataset.from_tensor_slices((x_train, y_train))
dataset = dataset.repeat().shuffle(x_train.shape[0]).batch(batch_size)
optimizer = tf.optimizers.SGD(learning_rate)
for batch_numb, (batch_xs, batch_ys) in enumerate(dataset.take(n_batches), 1):
gradients = grad(batch_xs, batch_ys)
optimizer.apply_gradients(zip(gradients, [weights, biases]))
y_pred = logistic_regression(batch_xs)
loss = cross_entropy(batch_ys, y_pred)
acc = accuracy(batch_ys, y_pred)
print("Batch number: %i, loss: %f, accuracy: %f" % (batch_numb, loss, acc))
i'm new to tensor and I only got write logs in tensorflow 1.x
When with tf.Session as sess left from tensorflow i get lost
in the other ways of making code.
Your code will look something like this using simple Tensorflow V2:
Start with the model creation, Logistic regression can be seen as a single layer perceptron with sigmoid activation so we will add an input layer with as many inputs as features and one output layer with sigmoid activation per each output class.
input = tf.keras.Input(shape=(nfeatures))
output = tf.keras.layers.Dense(nclasses,activation='sigmoid')(input)
model = tf.keras.Model(inputs=input,outputs=output,name='MyLinearRegression')
Than we create the optimizer and the loss function:
opt = tf.keras.optimizers.Adadelta()
lss = tf.keras.losses.categorical_crossentropy
met = tf.keras.metrics.Accuracy()
You have to use categorica_crossentropy or sparse_categorical_crossentropy depending on the labels (hot encoded or not). For this loss you may want to change the activation to softmax.
Now we can "compile" the model this way:
model.compile(optimizer=opt,loss=lss,metrics=met)
model.summary()
So now we can create the TensorBoard callback:
tensorboard_callback = tf.keras.callbacks.TensorBoard(log_dir=logdir,write_graph=True,update_freq='batch')
And than train like this:
model.fit(train,epochs=100,callbacks=[tensorboard_callback],validation_data = val)
If your dataset is a numpy dataset you can create a TF dataset like this:
dataset = tf.data.Dataset.from_tensor_slices((features,labels))
train = dataset.take(train_size)
test = dataset.skip(train_size).batch(batchsize)
val = test.skip(test_size).batch(batchsize)
test = test.take(test_size).batch(batchsize)
Where train is your train dataset, val the validation one and test the test dataset.
First of all you have to create a callback function to update Tensorboard:
tensorboard_callback = tf.keras.callbacks.TensorBoard(log_dir=logdir,write_graph=True,update_freq='batch')
Where logdir is a string to an existing directory.
than you can compile your model like this:
model.compile(optimizer=opt,loss=lss,metrics=met)
Where obviously opt is your optimizer, lss your loss function and optionally met your metrics.
Now you can train the model like this:
model.fit(train,epochs=100,callbacks=[tensorboard_callback],validation_data = val)
It will create a Tensorboard instance and you will see the address in the terminal. You can copy the link in your browser and see it.
I see that you are still using the "old" Tensorflow v1 way of compiling and creating the model. Using model.compile and model.fit is easyer and faster (in my opinion) if you aren't using particoular training methods. (You can't greate GANs this way for example).
Related
I am working on a recommendation system using a deep autoencoder model. How can I define the mean absolute error(MAE) loss function, and use it to calculate the model accuracy.
Here is the model
model = deep_model(train_, layers, activation, last_activation, dropout, regularizer_encode, regularizer_decode)
model.compile(optimizer=Adam(lr=0.001), loss="mse", metrics=[ ] )
model.summary()
define the data-validate
data_valid =(train, validate)
hist_model = model.fit(x=train, y=train,
epochs=100,
batch_size=128,
validation_data= data_valid, verbose=2, shuffle=True)
you can define it yourself:
import keras.backend as K
def my_mae(y_true, y_pred):
return K.mean(K.abs(y_pred - y_true), axis=-1) # -1 is correct, using None gives different result '''
then do this:
model.compile(optimizer=Adam(learning_rate=1e-2), loss=my_mae)
but it still a better idea to call the one implemented in keras, in this way:
model.compile(optimizer=Adam(learning_rate=1e-2), loss=tf.keras.losses.MeanAbsoluteError(name="mean_absolute_error"))
I think you can you the scikit-learn function here. This will return the mae of your prediction.
I suggest fitting the model as:
model.compile(optimizer=Adam(lr=0.001), loss="mae", metrics=[])
# instead of loss="mse"
model_history = model.fit(
X_train, # instead of: x=train, y=train
y_train, # why x and y are the same as 'train'?
epochs=100,
batch_size=128,
validation_data=(X_test,y_test))
After train your model, make a prediction:
predicton = model.predict(X_test)
And get the MAE by:
mae_error = mean_absolute_error(y_test, prediction)
i did the used the RMSE to measure the model and the results were good. below the defined loss=masked_ms and metrics=[masked_rmse_clip] function
for the loss function
def masked_mse(y_true, y_pred):
# masked function
mask_true = K.cast(K.not_equal(y_true, 0), K.floatx())
# masked squared error
masked_squared_error = K.square(mask_true * (y_true - y_pred))
masked_mse = K.sum(masked_squared_error, axis=-1) / K.maximum(K.sum(mask_true, axis=-1), 1)
return masked_mse
for the metric
def masked_rmse_clip(y_true, y_pred):
# masked function
mask_true = K.cast(K.not_equal(y_true, 0), K.floatx())
y_pred = K.clip(y_pred, 1, 5)
# masked squared error
masked_squared_error = K.square(mask_true * (y_true - y_pred))
masked_mse = K.sqrt(K.sum(masked_squared_error, axis=-1) / K.maximum(K.sum(mask_true, axis=-1), 1))
return masked_mse
the model
model = deep_model(train, layers, activation, last_activation, dropout, regularizer_encode, regularizer_decode)
model.compile(optimizer=Adam(lr=0.001), loss=masked_mse, metrics=[masked_rmse_clip] )
model.summary()
data_valid =(train, validate)
hist_model = model.fit(x=train, y=train,
epochs=100,
batch_size=128,
validation_data= data_valid, verbose=2, shuffle=True)
i get this output after 100 epoch
Epoch 100/100
48/48 - 6s - loss: 0.9418 - masked_rmse_clip: 0.8024 - val_loss: 0.9853 - val_masked_rmse_clip: 0.8010
I want something like this for the MAE. so i need help with the loss and metrics function for MAE.
I want to customize the fit function of the model in order to apply the gradient descent on the weights only if the model improved its predictions on the validation data. The reason for this is that I want to prevent overfitting.
According to this guide it should be possible to customize the fit function of the model. However, the following code runs into errors:
class CustomModel(tf.keras.Model):
def train_step(self, data):
x, y = data
with tf.GradientTape() as tape:
y_pred = self(x, training=True)
loss = self.compiled_loss(y, y_pred, regularization_losses=self.losses)
trainable_vars = self.trainable_variables
gradients = tape.gradient(loss, trainable_vars)
### check and apply gradient
Y_pred_val = self.predict(X_val) # this does not work
acc_val = calculate_accuracy(Y_val, Y_pred_val)
if acc_val > last_acc_val:
self.optimizer.apply_gradients(zip(gradients, trainable_vars))
###
self.compiled_metrics.update_state(y, y_pred)
return_obj = {m.name: m.result() for m in self.metrics}
return_obj["acc_val"] = acc_val
return return_obj
How could it be possible to evaluate the model inside the fit function?
You don't have to subclass fit() for this. You can just make a custom training loop. Look how I did that:
import os
os.environ['TF_CPP_MIN_LOG_LEVEL'] = '3'
from tensorflow.keras import Model
import tensorflow as tf
from tensorflow.keras.layers import Dense, Conv2D, MaxPooling2D, Flatten, Concatenate
import tensorflow_datasets as tfds
from tensorflow.keras.regularizers import l1, l2, l1_l2
from collections import deque
dataset, info = tfds.load('mnist',
with_info=True,
split='train',
as_supervised=False)
TAKE = 1_000
data = dataset.map(lambda x: (tf.cast(x['image'],
tf.float32), x['label'])).shuffle(TAKE).take(TAKE)
len_train = int(8e-1*TAKE)
train = data.take(len_train).batch(8)
test = data.skip(len_train).take(info.splits['train'].num_examples - len_train).batch(8)
class CNN(Model):
def __init__(self):
super(CNN, self).__init__()
self.layer1 = Dense(32, activation=tf.nn.relu,
kernel_regularizer=l1(1e-2),
input_shape=info.features['image'].shape)
self.layer2 = Conv2D(filters=16,
kernel_size=(3, 3),
strides=(1, 1),
activation='relu',
input_shape=info.features['image'].shape)
self.layer3 = MaxPooling2D(pool_size=(2, 2))
self.layer4 = Conv2D(filters=32,
kernel_size=(3, 3),
strides=(1, 1),
activation=tf.nn.elu,
kernel_initializer=tf.keras.initializers.glorot_normal)
self.layer5 = MaxPooling2D(pool_size=(2, 2))
self.layer6 = Flatten()
self.layer7 = Dense(units=64,
activation=tf.nn.relu,
kernel_regularizer=l2(1e-2))
self.layer8 = Dense(units=64,
activation=tf.nn.relu,
kernel_regularizer=l1_l2(l1=1e-2, l2=1e-2))
self.layer9 = Concatenate()
self.layer10 = Dense(units=info.features['label'].num_classes)
def call(self, inputs, training=None, **kwargs):
b = self.layer1(inputs)
a = self.layer2(inputs)
a = self.layer3(a)
a = self.layer4(a)
a = self.layer5(a)
a = self.layer6(a)
a = self.layer8(a)
b = self.layer7(b)
b = self.layer6(b)
x = self.layer9([a, b])
x = self.layer10(x)
return x
cnn = CNN()
loss_object = tf.keras.losses.SparseCategoricalCrossentropy(from_logits=True)
train_loss = tf.keras.metrics.Mean()
test_loss = tf.keras.metrics.Mean()
train_acc = tf.keras.metrics.SparseCategoricalAccuracy()
test_acc = tf.keras.metrics.SparseCategoricalAccuracy()
optimizer = tf.keras.optimizers.Nadam()
template = 'Epoch {:3} Train Loss {:7.4f} Test Loss {:7.4f} ' \
'Train Acc {:6.2%} Test Acc {:6.2%} '
epochs = 5
early_stop = epochs//50
loss_hist = deque()
acc_hist = deque(maxlen=1)
acc_hist.append(0)
for epoch in range(1, epochs + 1):
train_loss.reset_states()
test_loss.reset_states()
train_acc.reset_states()
test_acc.reset_states()
for images, labels in train:
with tf.GradientTape() as tape:
logits = cnn(images, training=True)
loss = loss_object(labels, logits)
train_loss(loss)
train_acc(labels, logits)
current_acc = tf.metrics.SparseCategoricalAccuracy()(labels, logits)
if tf.greater(current_acc, acc_hist[-1]):
print('IMPROVEMENT.')
gradients = tape.gradient(loss, cnn.trainable_variables)
optimizer.apply_gradients(zip(gradients, cnn.trainable_variables))
acc_hist.append(current_acc)
for images, labels in test:
logits = cnn(images, training=False)
loss = loss_object(labels, logits)
test_loss(loss)
test_acc(labels, logits)
print(template.format(epoch,
train_loss.result(),
test_loss.result(),
train_acc.result(),
test_acc.result()))
if len(loss_hist) > early_stop and loss_hist.popleft() < min(loss_hist):
print('Early stopping. No validation loss decrease in %i epochs.' % early_stop)
break
Output:
IMPROVEMENT.
IMPROVEMENT.
IMPROVEMENT.
IMPROVEMENT.
Epoch 1 Train Loss 21.1698 Test Loss 21.3391 Train Acc 37.13% Test Acc 38.50%
IMPROVEMENT.
IMPROVEMENT.
IMPROVEMENT.
Epoch 2 Train Loss 13.8314 Test Loss 12.2496 Train Acc 50.88% Test Acc 52.50%
Epoch 3 Train Loss 13.7594 Test Loss 12.5884 Train Acc 51.75% Test Acc 53.00%
Epoch 4 Train Loss 13.1418 Test Loss 13.2374 Train Acc 52.75% Test Acc 51.50%
Epoch 5 Train Loss 13.6471 Test Loss 13.3157 Train Acc 49.63% Test Acc 51.50%
Here's the part that did the job. It's a deque and it skips the application of gradients if the last element of the deque is smaller.
for images, labels in train:
with tf.GradientTape() as tape:
logits = cnn(images, training=True)
loss = loss_object(labels, logits)
train_loss(loss)
train_acc(labels, logits)
current_acc = tf.metrics.SparseCategoricalAccuracy()(labels, logits)
if tf.greater(current_acc, acc_hist[-1]):
print('IMPROVEMENT.')
gradients = tape.gradient(loss, cnn.trainable_variables)
optimizer.apply_gradients(zip(gradients, cnn.trainable_variables))
acc_hist.append(current_acc)
Rather than create a custom fit I think it would be easier to use the callback ModelCheckpoint.
What you are trying to do is get the model that has the lowest validation error. Set it up to monitor validation loss. That way it will save the best model even if the network starts to over fit. Documentation is here.
If you do not get a model with a satisfactory validation accuracy then you will have to take other measures.
First look at your training accuracy.
My experience is that you should achieve at least 95%.
If the training accuracy is good but the validation accuracy is poor and degrades as you run more epochs that is a sign of over fitting.
You did not show the model but if you are doing classification you will probably have dense layers with the final layer using softmax activation.
Start out with model with only one dense layer and see if it trains well.
If not you may have to add additional dense hidden layers. If you do include a drop out layer to help prevent over fitting. You might also consider using regularizers. Documentation is
here..
I also find you can get improved performance if you dynamically adjust the learning rate. The callback ReduceLROnPlateau enables that capability.
Set it up to monitor validation loss and to reduce the learning rate by a factor if the loss fails to decrease. Documentation is here.
I'm training a model using TensorFlow 2.0 using tf.GradientTape(), but I find that the model's accuracy is 95% if I use tf.keras.losses.BinaryCrossentropy, but degrade to 75% if I use tf.keras.losses.binary_crossentropy. So I'm confused about the difference about the same metric here?
import pandas as pd
import numpy as np
import tensorflow as tf
from tensorflow.keras import layers
from sklearn.model_selection import train_test_split
def read_data():
red_wine = pd.read_csv("https://archive.ics.uci.edu/ml/machine-learning-databases/wine-quality/winequality-red.csv", sep=";")
white_wine = pd.read_csv("https://archive.ics.uci.edu/ml/machine-learning-databases/wine-quality/winequality-white.csv", sep=";")
red_wine["type"] = 1
white_wine["type"] = 0
wines = red_wine.append(white_wine)
return wines
def get_x_y(df):
x = df.iloc[:, :-1].values.astype(np.float32)
y = df.iloc[:, -1].values.astype(np.int32)
return x, y
def build_model():
inputs = layers.Input(shape=(12,))
dense1 = layers.Dense(12, activation="relu", name="dense1")(inputs)
dense2 = layers.Dense(9, activation="relu", name="dense2")(dense1)
outputs = layers.Dense(1, activation = "sigmoid", name="outputs")(dense2)
model = tf.keras.Model(inputs=inputs, outputs=outputs)
return model
def generate_dataset(df, batch_size=32, shuffle=True, train_or_test = "train"):
x, y = get_x_y(df)
ds = tf.data.Dataset.from_tensor_slices((x, y))
if shuffle:
ds = ds.shuffle(10000)
if train_or_test == "train":
ds = ds.batch(batch_size)
else:
ds = ds.batch(len(df))
return ds
# loss_object = tf.keras.losses.binary_crossentropy
loss_object = tf.keras.losses.BinaryCrossentropy()
optimizer = tf.keras.optimizers.Adam(learning_rate=0.001)
def train_step(model, optimizer, x, y):
with tf.GradientTape() as tape:
pred = model(x, training=True)
loss = loss_object(y, pred)
grads = tape.gradient(loss, model.trainable_variables)
optimizer.apply_gradients(zip(grads, model.trainable_variables))
def train_model(model, train_ds, epochs=10):
for epoch in range(epochs):
print(epoch)
for x, y in train_ds:
train_step(model, optimizer, x, y)
def main():
data = read_data()
train, test = train_test_split(data, test_size=0.2, random_state=23)
train_ds = generate_dataset(train, 32, True, "train")
test_ds = generate_dataset(test, 32, False, "test")
model = build_model()
train_model(model, train_ds, 10)
model.compile(loss='binary_crossentropy',
optimizer='adam',
metrics=['accuracy']
)
model.evaluate(test_ds)
main()
They should indeed work the same; BinaryCrossentropy uses binary_crossentropy, with difference apparent in docstring descriptions; former's intended for two class labels, whereas later supports an arbitrary class count. However, if passing in targets in expected format, both apply same preprocessing before calling backend's binary_crossentropy, which does the actual computing.
The difference you observe is likely a reproducibility issue; ensure you set the random seed - see function below. For a more complete answer on reproducibility, see here.
Function
def reset_seeds(reset_graph_with_backend=None):
if reset_graph_with_backend is not None:
K = reset_graph_with_backend
K.clear_session()
tf.compat.v1.reset_default_graph()
print("KERAS AND TENSORFLOW GRAPHS RESET") # optional
np.random.seed(1)
random.seed(2)
tf.compat.v1.set_random_seed(3)
print("RANDOM SEEDS RESET") # optional
Usage:
import tensorflow as tf
import tensorflow.keras.backend as K
reset_seeds(K)
Thanks, I find the reasons of the inconsistent accuracy:
The shape of outputs in the model is (None, 1), but the feeded label is (None, ), which cause a wrong meaning with python's broadcast mechanism.
In the source code of tf.keras.losses.BinaryCrossentropy(), while calculating the loss, both y_pred and y_true are processed through a function called squeeze_or_expand_dimensions, which is lacked in tf.keras.losses.binary_crossentropy.
Note: Take care that whether the shape is consistent between input data and model outputs.
I wish to view the final output of training a tf.keras model. In this case it would be an array of predictions from the softmax function, e.g. [0,0,0,1,0,1].
Other threads on here have suggested using model.predict(training_data), but this won't work for my situation since I am using dropout at training and validation, so neurons are randomly dropped and predicting again with the same data will give a different result.
def get_model():
inputs = tf.keras.layers.Input(shape=(input_dims,))
x = tf.keras.layers.Dropout(rate=dropout_rate)(inputs, training=True)
x = tf.keras.layers.Dense(units=29, activation='relu')(x)
x = tf.keras.layers.Dropout(rate=dropout_rate)(x, training=True)
x = tf.keras.layers.Dense(units=15, activation='relu')(x)
outputs = tf.keras.layers.Dense(2, activation='softmax')(x)
model = tf.keras.Model(inputs=inputs, outputs=outputs)
model.compile(optimizer='adam',
loss='sparse_categorical_crossentropy',
metrics=['sparse_categorical_accuracy'])
return model
myModel = get_model()
myModel.summary()
myModel.fit(X_train, y_train,
batch_size = batch_size,
epochs= epochs,
verbose = 1,
validation_data = (X_val, y_val))
In tensorflow, you can grab the output of a model after training quite easily. Here is an example from a Github repo:
input = tf.placeholder(tf.float32, shape=[None, INPUT_DIMS])
labels = tf.placeholder(tf.float32, shape=[None])
hidden = tf.nn.tanh(make_nn_layer(normalized, NUM_HIDDEN))
logits = make_nn_layer(hidden, NUM_CLASSES)
outputs = tf.argmax(logits, 1)
int_labels = tf.to_int64(labels)
cross_entropy = tf.nn.sparse_softmax_cross_entropy_with_logits(logits, int_labels, name='xentropy')
train_step = tf.train.AdamOptimizer().minimize(cross_entropy)
correct_prediction = tf.equal(outputs, int_labels)
accuracy = tf.reduce_mean(tf.cast(correct_prediction, tf.float32))
with tf.Session() as sess:
sess.run(tf.initialize_all_variables())
validation_dict = {
input: validation_data[:,0:7],
labels: validation_data[:,7],}
for i in range(NUM_BATCHES):
batch = training_data[numpy.random.choice(training_size, BATCH_SIZE, False),:]
train_step.run({input: batch[:,0:7], labels: batch[:,7]})
if i % 100 == 0 or i == NUM_BATCHES - 1:
print('Accuracy %.2f%% at step %d' % (accuracy.eval(validation_dict) * 100, i))
output_data = outputs.eval({input: data_vector[:,0:7]})
The only output I can get from the trained model appears to be a history object. There is also a myModel.output object, but it is a tensor that I can't evaluate without putting data into it. Any ideas?
As far as I know, you can't turn off the dropout after passing training=True when calling the layers (unless you transfer the weights to a new model with the same architecture). However, instead you can build and train your model in normal case (i.e. without using training argument in the calls) and then selectively turn on and off the dropout layer in test phase by defining a backend function (i.e. keras.backend.function()) and setting the learning phase (i.e. keras.backend.learning_phase()):
# build your model normally (i.e. without using `training=True` argument)
# train your model...
from keras import backend as K
func = K.function(model.inputs + [K.learning_phase()], model.outputs)
# run the model with dropout layers being active, i.e. learning_phase == 1
preds = func(list_of_input_arrays + [1])
# run the model with dropout layers being inactive, i.e. learning_phase == 0
preds = func(list_of_input_arrays + [0])
Update: As I suggested above, another approach is to define a new model with the same architecture but without setting training=True, and then transfer the weights from the trained model to this new model. To achieve this, I just add a training argument to your get_model() function:
def get_model(training=None):
inputs = tf.keras.layers.Input(shape=(input_dims,))
x = tf.keras.layers.Dropout(rate=dropout_rate)(inputs, training=training)
x = tf.keras.layers.Dense(units=29, activation='relu')(x)
x = tf.keras.layers.Dropout(rate=dropout_rate)(x, training=training)
x = tf.keras.layers.Dense(units=15, activation='relu')(x)
outputs = tf.keras.layers.Dense(2, activation='softmax')(x)
model = tf.keras.Model(inputs=inputs, outputs=outputs)
model.compile(optimizer='adam',
loss='sparse_categorical_crossentropy',
metrics=['sparse_categorical_accuracy'])
return model
# build a model with dropout layers active in both training and test phases
myModel = get_model(training=True)
# train the model
myModel.fit(...)
# build a clone of the model with dropouts deactivated in test phase
myTestModel = get_model() # note: the `training` is `None` by default
# transfer the weights from the trained model to this model
myTestModel.set_weights(myModel.get_weights())
# use the new model in test phase; the dropouts would not be active
myTestModel.predict(...)
I am trying to calculate the recall in both binary and multi class (one hot encoded) classification scenarios for each class after each epoch in a model that uses Tensorflow 2's Keras API. e.g. for binary classification I'd like to be able to do something like
import tensorflow as tf
model = tf.keras.Sequential()
model.add(...)
model.add(tf.keras.layers.Dense(1))
model.compile(metrics=[binary_recall(label=0), binary_recall(label=1)], ...)
history = model.fit(...)
plt.plot(history.history['binary_recall_0'])
plt.plot(history.history['binary_recall_1'])
plt.show()
or in a multi class scenario I'd like to do something like
model = tf.keras.Sequential()
model.add(...)
model.add(tf.keras.layers.Dense(3))
model.compile(metrics=[recall(label=0), recall(label=1), recall(label=2)], ...)
history = model.fit(...)
plt.plot(history.history['recall_0'])
plt.plot(history.history['recall_1'])
plt.plot(history.history['recall_2'])
plt.show()
I'm working on a classifier for an unbalanced dataset and want to be able to see at what point the recall for my minority class(s) starts to degrade.
I found an implementation of precision for a specific class in a multi-class classifier here https://stackoverflow.com/a/41717938/373655. I'm am trying to adapt this into what I need but keras.backend is still pretty foreign to me so any help would be greatly appreciated.
I am also not clear on if I can use Keras metrics (as they are calculated at the end of each batch and then averaged) or if I need to use Keras callbacks (which can run at the end of each epoch). It seems to me like it shouldn't make a difference for recall (e.g. 8/10 == (3/5 + 5/5) / 2) but this is why recall was removed in Keras 2 so maybe I'm missing something (https://github.com/keras-team/keras/issues/5794)
Edit - partial solution (multi-class classification)
#mujjiga's solution works for both binary classification and multi-class classification but as #P-Gn pointed out, tensorflow 2's Recall metric supports this out of the box for multi-class classification. e.g.
from tensorflow.keras.metrics import Recall
model = ...
model.compile(loss='categorical_crossentropy', metrics=[
Recall(class_id=0, name='recall_0')
Recall(class_id=1, name='recall_1')
Recall(class_id=2, name='recall_2')
])
history = model.fit(...)
plt.plot(history.history['recall_2'])
plt.plot(history.history['val_recall_2'])
plt.show()
We can use classification_report of sklearn and keras Callback to achieve this.
Working code sample (with comments)
import tensorflow as tf
import keras
from tensorflow.python.keras.layers import Dense, Input
from tensorflow.python.keras.models import Sequential
from tensorflow.python.keras.callbacks import Callback
from sklearn.metrics import recall_score, classification_report
from sklearn.datasets import make_classification
import numpy as np
import matplotlib.pyplot as plt
# Model -- Binary classifier
binary_model = Sequential()
binary_model.add(Dense(16, input_shape=(2,), activation='relu'))
binary_model.add(Dense(8, activation='relu'))
binary_model.add(Dense(1, activation='sigmoid'))
binary_model.compile('adam', loss='binary_crossentropy')
# Model -- Multiclass classifier
multiclass_model = Sequential()
multiclass_model.add(Dense(16, input_shape=(2,), activation='relu'))
multiclass_model.add(Dense(8, activation='relu'))
multiclass_model.add(Dense(3, activation='softmax'))
multiclass_model.compile('adam', loss='categorical_crossentropy')
# callback to find metrics at epoch end
class Metrics(Callback):
def __init__(self, x, y):
self.x = x
self.y = y if (y.ndim == 1 or y.shape[1] == 1) else np.argmax(y, axis=1)
self.reports = []
def on_epoch_end(self, epoch, logs={}):
y_hat = np.asarray(self.model.predict(self.x))
y_hat = np.where(y_hat > 0.5, 1, 0) if (y_hat.ndim == 1 or y_hat.shape[1] == 1) else np.argmax(y_hat, axis=1)
report = classification_report(self.y,y_hat,output_dict=True)
self.reports.append(report)
return
# Utility method
def get(self, metrics, of_class):
return [report[str(of_class)][metrics] for report in self.reports]
# Generate some train data (2 class) and train
x, y = make_classification(n_features=2, n_redundant=0, n_informative=2,
random_state=1, n_clusters_per_class=1)
metrics_binary = Metrics(x,y)
binary_model.fit(x, y, epochs=30, callbacks=[metrics_binary])
# Generate some train data (3 class) and train
x, y = make_classification(n_features=2, n_redundant=0, n_informative=2,
random_state=1, n_clusters_per_class=1, n_classes=3)
y = keras.utils.to_categorical(y,3)
metrics_multiclass = Metrics(x,y)
multiclass_model.fit(x, y, epochs=30, callbacks=[metrics_multiclass])
# Plotting
plt.close('all')
plt.plot(metrics_binary.get('recall',0), label='Class 0 recall')
plt.plot(metrics_binary.get('recall',1), label='Class 1 recall')
plt.plot(metrics_binary.get('precision',0), label='Class 0 precision')
plt.plot(metrics_binary.get('precision',1), label='Class 1 precision')
plt.plot(metrics_binary.get('f1-score',0), label='Class 0 f1-score')
plt.plot(metrics_binary.get('f1-score',1), label='Class 1 f1-score')
plt.legend(loc='lower right')
plt.show()
plt.close('all')
for m in ['recall', 'precision', 'f1-score']:
for c in [0,1,2]:
plt.plot(metrics_multiclass.get(m,c), label='Class {0} {1}'.format(c,m))
plt.legend(loc='lower right')
plt.show()
Output
Advantages:
classification_report provides lots of metrics
Can calculate metrics on validation data on train data by passing the same to Metrics constructor.
In TF2, tf.keras.metrics.Recall gained a class_id member that enables to do just that. Example using FashionMNIST:
import tensorflow as tf
(x_train, y_train), _ = tf.keras.datasets.fashion_mnist.load_data()
x_train = x_train[..., None].astype('float32') / 255
y_train = tf.keras.utils.to_categorical(y_train)
input_shape = x_train.shape[1:]
model = tf.keras.Sequential([
tf.keras.layers.Conv2D(filters=64, kernel_size=2, padding='same', activation='relu', input_shape=input_shape),
tf.keras.layers.MaxPool2D(pool_size=2),
tf.keras.layers.Dropout(0.3),
tf.keras.layers.Conv2D(filters=32, kernel_size=2, padding='same', activation='relu'),
tf.keras.layers.MaxPool2D(pool_size=2),
tf.keras.layers.Dropout(0.3),
tf.keras.layers.Flatten(),
tf.keras.layers.Dense(units=256, activation='relu'),
tf.keras.layers.Dropout(0.5),
tf.keras.layers.Dense(units=10, activation='softmax')])
model.compile(loss='categorical_crossentropy', optimizer='Adam',
metrics=[tf.keras.metrics.Recall(class_id=i) for i in range(10)])
model.fit(x_train, y_train, batch_size=128, epochs=50)
In TF 1.13, tf.keras.metric.Recall does not have this class_id argument, but it can be added by subclassing (something that, somewhat suprisingly, seems impossible in the alpha release of TF2).
class Recall(tf.keras.metrics.Recall):
def __init__(self, *, class_id, **kwargs):
super().__init__(**kwargs)
self.class_id= class_id
def update_state(self, y_true, y_pred, sample_weight=None):
y_true = y_true[:, self.class_id]
y_pred = tf.cast(tf.equal(
tf.math.argmax(y_pred, axis=-1), self.class_id), dtype=tf.float32)
return super().update_state(y_true, y_pred, sample_weight)
There are multiple ways to do this but using a callback seems the best and most kerasy way of doing it. One side-note before I show you how:
I am also not clear on if I can use Keras metrics (as they are
calculated at the end of each batch and then averaged) or if I need to
use Keras callbacks (which can run at the end of each epoch).
This is not true. Keras' callbacks can use the following methods:
on_epoch_begin: called at the beginning of every epoch.
on_epoch_end: called at the end of every epoch.
on_batch_begin: called at the beginning of every batch.
on_batch_end: called at the end of every batch.
on_train_begin: called at the beginning of model training.
on_train_end: called at the end of model training.
This is true regardless of whether you are using keras or tf.keras.
Below you can find my implementation of a custom callback.
class RecallHistory(keras.callbacks.Callback):
def on_train_begin(self, logs={}):
self.recall = {}
def on_epoch_end(self, epoch, logs={}):
# Compute and store recall for each class here.
self.recall[...] = 42
history = RecallHistory()
model.fit(..., callbacks=[history])
print(history.recall)