preprocessing

os.mkdir('./images/')
alpha = 'a'
for i in range(0, 26): 
    os.mkdir('./images/' + alpha)
    alpha = chr(ord(alpha) + 1)

for file in os.listdir(rootdir):
    letter = file[0]
    try:
        shutil.copy(rootdir+file, './images/' + letter + '/' + file)
    except :
        print(file)
        
datagen = ImageDataGenerator(rotation_range=20,
                             shear_range=10,
                             validation_split=0.2)

train_generator = datagen.flow_from_directory('./images/',
                                              target_size=(28,28),
                                              subset='training')

val_generator = datagen.flow_from_directory('./images/',
                                            target_size=(28,28),
                                            subset='validation')