Equivalent of 'class_indices' attribute of 'flow_from_directory' object in case of 'ImageDataGenerator' object - tensorflow

Question

I am following a tutorial at https://medium.com/#vijayabhaskar96/tutorial-image-classification-with-keras-flow-from-directory-and-generators-95f75ebe5720
I am using 'ImageDataGenerator' object and want to predict the out put using the following method.
pred=model.predict_generator(test_generator,
steps=10,
verbose=1)
predicted_class_indices=np.argmax(pred,axis=1)
labels = (train_generator.class_indices)
labels = dict((v,k) for k,v in labels.items())
predictions = [labels[k] for k in predicted_class_indices]
But I am using Keras 'ImageDataGenerator' and 'flow_from_dataframe' object.
'ImageDataGenerator' has no 'class_indices' attribute. How can I get the indices of the classes

Answer 1

End to End example which uses ImageDataGenerator.flow_from_dataframe and which answers your question of How can I get the indices of the classes
from tensorflow.keras.models import Sequential
#Import from keras_preprocessing not from keras.preprocessing
from tensorflow.keras.preprocessing.image import ImageDataGenerator
from tensorflow.keras.layers import Dense, Activation, Flatten, Dropout, BatchNormalization
from tensorflow.keras.layers import Conv2D, MaxPooling2D
from tensorflow.keras import regularizers, optimizers
import pandas as pd
import numpy as np
def append_ext(fn):
return fn+".png"
traindf=pd.read_csv("trainLabels.csv",dtype=str)
testdf=pd.read_csv("sampleSubmission.csv",dtype=str)
traindf["id"]=traindf["id"].apply(append_ext)
testdf["id"]=testdf["id"].apply(append_ext)
datagen=ImageDataGenerator(rescale=1./255.,validation_split=0.25)
train_generator=datagen.flow_from_dataframe(
dataframe=traindf,
directory="train/",
x_col="id",
y_col="label",
subset="training",
batch_size=32,
seed=42,
shuffle=True,
class_mode="categorical",
target_size=(32,32))
valid_generator=datagen.flow_from_dataframe(
dataframe=traindf,
directory="train/",
x_col="id",
y_col="label",
subset="validation",
batch_size=32,
seed=42,
shuffle=True,
class_mode="categorical",
target_size=(32,32))
test_datagen=ImageDataGenerator(rescale=1./255.)
test_generator=test_datagen.flow_from_dataframe(
dataframe=testdf,
directory="test/",
x_col="id",
y_col=None,
batch_size=32,
seed=42,
shuffle=False,
class_mode=None,
target_size=(32,32))
model = Sequential()
model.add(Conv2D(32, (3, 3), padding='same',
input_shape=(32,32,3)))
model.add(Activation('relu'))
model.add(Conv2D(32, (3, 3)))
model.add(Activation('relu'))
model.add(MaxPooling2D(pool_size=(2, 2)))
model.add(Dropout(0.25))
model.add(Conv2D(64, (3, 3), padding='same'))
model.add(Activation('relu'))
model.add(Conv2D(64, (3, 3)))
model.add(Activation('relu'))
model.add(MaxPooling2D(pool_size=(2, 2)))
model.add(Dropout(0.25))
model.add(Flatten())
model.add(Dense(512))
model.add(Activation('relu'))
model.add(Dropout(0.5))
model.add(Dense(10, activation='softmax'))
model.compile(optimizers.RMSprop(lr=0.0001, decay=1e-6),loss="categorical_crossentropy",metrics=["accuracy"])
STEP_SIZE_TRAIN=train_generator.n//train_generator.batch_size
STEP_SIZE_VALID=valid_generator.n//valid_generator.batch_size
STEP_SIZE_TEST=test_generator.n//test_generator.batch_size
model.fit_generator(generator=train_generator,
steps_per_epoch=STEP_SIZE_TRAIN,
validation_data=valid_generator,
validation_steps=STEP_SIZE_VALID,
epochs=10
)
model.evaluate_generator(generator=valid_generator,
steps=STEP_SIZE_TEST)
test_generator.reset()
pred=model.predict_generator(test_generator,
steps=STEP_SIZE_TEST,
verbose=1)
predicted_class_indices=np.argmax(pred,axis=1)
labels = (train_generator.class_indices)
labels = dict((v,k) for k,v in labels.items())
predictions = [labels[k] for k in predicted_class_indices]
Finally, we print the Classes as shown below:
print(predictions)
Output of above print statement is:
['bird',
'dog',
'bird',
'cat',
'horse',
'deer',
'deer',
'airplane',
'cat',
'cat',
'ship',
'bird',
'automobile',..........]
For more information, please refer this Article written by Vijaya Bhaskar.
Hope this helps. Happy Learning!