Why is my code outputting nan? I'm using a sequential model with a 30x1 input vector and a single value output. I'm using tensorflow and python. This is one of my firs
While True:
# Define a simple sequential model
def create_model():
model = tf.keras.Sequential([
keras.layers.Dense(30, activation='relu',input_shape=(30,)),
keras.layers.Dense(12, activation='relu'),
keras.layers.Dropout(0.2),
keras.layers.Dense(7, activation='relu'),
keras.layers.Dense(1, activation = 'sigmoid')
])
model.compile(optimizer='adam',
loss=tf.keras.losses.SparseCategoricalCrossentropy(from_logits=True),
metrics=[tf.keras.metrics.SparseCategoricalAccuracy()])
return model
# Create a basic model instance
model = create_model()
# Display the model's architecture
model.summary()
train_labels=[1]
test_labels=[1]
train_images= [[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30]]
test_images=[[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30]]
model.fit(train_images,
train_labels,
epochs=10,
validation_data=(test_images, test_labels),
verbose=1)
print('predicted:',model.predict(train_images))
You are using SparseCategoricalCrossentropy. It expects labels to be integers starting from 0. So, you have only one label 1, but it means you have at least two categories - 0 and 1. So you need at least two neurons in the last layer:
keras.layers.Dense(2, activation = 'sigmoid')
( If your goal is classification, you should maybe consider to use softmax instead of sigmoid, without from_logits=True )
You're using the wrong loss function for those labels. You need to use BinaryCrossentropy.
Change:
model.compile(optimizer='adam',
loss=tf.keras.losses.SparseCategoricalCrossentropy(from_logits=True),
metrics=[tf.keras.metrics.SparseCategoricalAccuracy()])
To:
model.compile(optimizer='adam',
loss=tf.keras.losses.BinaryCrossentropy,
metrics=[tf.keras.metrics.BinaryAccuracy()])
Related
I am new to Keras and trying to write my first code. I want to understand what 'model.predict' should return. Consider a simple model below.
model = keras.Sequential()
model.add(keras.layers.Dense(12, input_dim=232, activation='relu'))
model.add(keras.layers.Dense(232, activation='relu'))
model.add(keras.layers.Dense(1, activation='sigmoid'))
# compile the keras model
model.compile(loss='binary_crossentropy', optimizer='adam', metrics=['accuracy'])
# fit the keras model on the dataset
model.fit(vSignal, vLabels, epochs=15, batch_size=100 )
# evaluate the keras model
_, accuracy = model.evaluate(vSignal, vLabels)
print('Accuracy: %.2f' % (accuracy*100))
pred=model.predict(vSignalT)
Consider we train the "model" with "vSignal" and "vLabels" as shown above. Now consider that the accuracy of the model as given by model.evaluate is 100%. Now if we give same data 'vSignal' to 'model.predict' should we get the 'vLabels' return?
pred=model.predict(vSignalT) returns a numpy arrays of predictions.
each row consists of one of the vlabels that the model predicted.
for more information refer to here
save return value of fit function:
hist = model.fit(vSignal, vLabels, epochs=15, batch_size=100 );
then check the
hist.history["accuracy"]
I am trying to create a simple 3 class deep learning classifier using keras as follows:
clf = Sequential()
clf.add(Dense(20, activation='relu', input_dim=NUM_OF_FEATURES))
clf.add(Dense(10, activation='relu'))
clf.add(Dense(3, activation='relu'))
clf.add(Dense(1, activation='softmax'))
# Model Compilation
clf.compile(optimizer = 'adam',
loss = 'categorical_crossentropy',
metrics = ['accuracy'])
# Training the model
clf.fit(X_train,
y_train,
epochs=10,
batch_size=16,
validation_data=(X_val, y_val))
How after training while predicting, it is only predicting the same class (class 1) out of the 3 classes ALWAYS.
Is my network architecture not correct?
I am new to deep learning and AI.
If you want a network to classify three classes, your last dense layer should have three output nodes. In the example, the last dense layer has one output node.
clf = Sequential()
clf.add(Dense(20, activation='relu', input_dim=NUM_OF_FEATURES))
clf.add(Dense(10, activation='relu'))
clf.add(Dense(3, activation='relu'))
clf.add(Dense(3, activation='softmax'))
For each input sample, the output will be three values, all of which sum to one. These represent the probabilities that the input belongs to each class.
Regarding the loss function, if you want to use cross entropy, you have a choice between sparse categorical cross entropy and categorical cross entropy. The latter expects ground truth labels to be one-hot encoded (you can use tf.one_hot for this). In other words, the shape of the labels is the same as the shape as the network's output. Sparse categorical cross entropy, on the other hand, expects labels with a rank N-1, where N is the rank of the neural network's output. In order words, these are the labels before one-hot encoding.
When the model is used for inference, the predicted class values can be retrieved with argmax of the last dimension of the predictions.
predictions = clf.predict(x)
classes = predictions.argmax(-1)
I modified the existing activation function and using it in the Convolutional layer of the Neural Network. I would like to know how does it perform compared to the existing activation function.Is there any method/function to plot in a graph the results(matrix values) after each Neural network layer,so that I could customise my activation function according to the values for better results?
model = Sequential()
e = Embedding(vocab_size, 100, weights=[embedding_matrix], input_length=max_length, trainable=False)
model.add(e)
model.add(Conv1D(64,kernel_size,padding='valid',activation=newactivation,strides=1))
model.add(MaxPooling1D(pool_size=pool_size))
model.add(Conv1D(256,kernel_size,padding='valid',activation=newactivation,strides=1))
model.add(MaxPooling1D(pool_size=pool_size))
model.add(Bidirectional(GRU(gru_output_size, dropout=0.2, recurrent_dropout=0.2)))
model.add(Bidirectional(LSTM(lstm_output_size)))
model.add(Dense(nclass, activation='softmax'))
model.compile(optimizer='rmsprop', loss='binary_crossentropy', metrics=['accuracy'])
print(model.summary())
model.fit(padded_docs,y_train, epochs=epoch_size, verbose=0)
loss, accuracy = model.evaluate(tpadded_docs, y_test, verbose=0)
I cannot comment yet so I post this as an answer:
Refer to the Keras FAQ: "How can I obtain the output of an intermediate layer?"
It shows you how you can access the output of each layer. If you are using the version that uses the keras function, you can even access the output of the model in the learning phase (if your model contains layer that behave differently in training vs. testing).
I am trying to fine-tune pre-trained Inceptionv3 in Keras for a multi-label (17) prediction problem.
Here's the code:
# create the base pre-trained model
base_model = InceptionV3(weights='imagenet', include_top=False)
# add a new top layer
x = base_model.output
predictions = Dense(17, activation='sigmoid')(x)
# this is the model we will train
model = Model(inputs=base_model.input, outputs=predictions)
# we need to recompile the model for these modifications to take effect
# we use SGD with a low learning rate
from keras.optimizers import SGD
model.compile(loss='binary_crossentropy', # We NEED binary here, since categorical_crossentropy l1 norms the output before calculating loss.
optimizer=SGD(lr=0.0001, momentum=0.9))
# Fit the model (Add history so that the history may be saved)
history = model.fit(x_train, y_train,
batch_size=128,
epochs=1,
verbose=1,
callbacks=callbacks_list,
validation_data=(x_valid, y_valid))
But I got into the following error message and had trouble deciphering what it is saying:
ValueError: Error when checking target: expected dense_1 to have 4
dimensions, but got array with shape (1024, 17)
It seems to have something to do with that it doesn't like my one-hot encoding for the labels as target. But how do I get 4 dimensions target?
It turns out that the code copied from https://keras.io/applications/ would not run out-of-the-box.
The following post has helped me:
Keras VGG16 fine tuning
The changes I need to make are the following:
Add in the input shape to the model definition base_model = InceptionV3(weights='imagenet', include_top=False, input_shape=(299,299,3)), and
Add a Flatten() layer to flatten the tensor output:
x = base_model.output
x = Flatten()(x)
predictions = Dense(17, activation='sigmoid')(x)
Then the model works for me!
I have a network in Keras with many outputs, however, my training data only provides information for a single output at a time.
At the moment my method for training has been to run a prediction on the input in question, change the value of the particular output that I am training and then doing a single batch update. If I'm right this is the same as setting the loss for all outputs to zero except the one that I'm trying to train.
Is there a better way? I've tried class weights where I set a zero weight for all but the output I'm training but it doesn't give me the results I expect?
I'm using the Theano backend.
Outputting multiple results and optimizing only one of them
Let's say you want to return output from multiple layers, maybe from some intermediate layers, but you need to optimize only one target output. Here's how you can do it:
Let's start with this model:
inputs = Input(shape=(784,))
x = Dense(64, activation='relu')(inputs)
# you want to extract these values
useful_info = Dense(32, activation='relu', name='useful_info')(x)
# final output. used for loss calculation and optimization
result = Dense(1, activation='softmax', name='result')(useful_info)
Compile with multiple outputs, set loss as None for extra outputs:
Give None for outputs that you don't want to use for loss calculation and optimization
model = Model(inputs=inputs, outputs=[result, useful_info])
model.compile(optimizer='rmsprop',
loss=['categorical_crossentropy', None],
metrics=['accuracy'])
Provide only target outputs when training. Skipping extra outputs:
model.fit(my_inputs, {'result': train_labels}, epochs=.., batch_size=...)
# this also works:
#model.fit(my_inputs, [train_labels], epochs=.., batch_size=...)
One predict to get them all
Having one model you can run predict only once to get all outputs you need:
predicted_labels, useful_info = model.predict(new_x)
In order to achieve this I ended up using the 'Functional API'. You basically create multiple models, using the same layers input and hidden layers but different output layers.
For example:
https://keras.io/getting-started/functional-api-guide/
from keras.layers import Input, Dense
from keras.models import Model
# This returns a tensor
inputs = Input(shape=(784,))
# a layer instance is callable on a tensor, and returns a tensor
x = Dense(64, activation='relu')(inputs)
x = Dense(64, activation='relu')(x)
predictions_A = Dense(1, activation='softmax')(x)
predictions_B = Dense(1, activation='softmax')(x)
# This creates a model that includes
# the Input layer and three Dense layers
modelA = Model(inputs=inputs, outputs=predictions_A)
modelA.compile(optimizer='rmsprop',
loss='categorical_crossentropy',
metrics=['accuracy'])
modelB = Model(inputs=inputs, outputs=predictions_B)
modelB.compile(optimizer='rmsprop',
loss='categorical_crossentropy',
metrics=['accuracy'])