I believed that, if I have a binary-classification problem then I should always have only 1 node in the last layer, since the last layer has to decide about the classification. However, in the following code it is not true.
Let's download the pizza/steak datasets (image dataset) and prepare the data using the ImageDataGenerator:
import zipfile
import tensorflow as tf
from tensorflow.keras.layers import Input, Dense, Dropout, Conv2D, MaxPooling2D, Flatten
from tensorflow.keras.preprocessing.image import ImageDataGenerator
from tensorflow.keras.preprocessing import image_dataset_from_directory
from tensorflow.keras.applications import EfficientNetB0, resnet50
from tensorflow.keras.models import Sequential
import numpy as np
import pandas as pd
!wget https://storage.googleapis.com/ztm_tf_course/food_vision/pizza_steak.zip
zip_ref = zipfile.ZipFile("pizza_steak.zip", "r")
zip_ref.extractall()
zip_ref.close()
train_directory = './pizza_steak/train/'
test_directory = './pizza_steak/test/'
IMAGE_SIZE = (224, 224)
image_data_generator = ImageDataGenerator(rescale=1. / 255,
zoom_range=0.2,
shear_range=0.2,
rotation_range=0.2)
train_dt = image_data_generator.flow_from_directory(directory=train_directory,
class_mode='categorical',
batch_size=32,
target_size=IMAGE_SIZE)
test_dt = image_data_generator.flow_from_directory(directory=test_directory,
class_mode='categorical',
batch_size=32,
target_size=IMAGE_SIZE)
and then build, compile a neural-network and fit the data on it:
model = Sequential()
model.add(Conv2D(filters=16, kernel_size=3, activation='relu'))
model.add(Conv2D(filters=16, kernel_size=3, activation='relu'))
model.add(MaxPooling2D())
model.add(Conv2D(filters=16, kernel_size=3, activation='relu'))
model.add(Conv2D(filters=16, kernel_size=3, activation='relu'))
model.add(MaxPooling2D())
model.add(Flatten())
model.add(Dense(1, activation='sigmoid'))
model.compile(loss='binary_crossentropy', optimizer='adam', metrics=['accuracy'])
model.fit(train_dt,
epochs=5,
validation_data=test_dt,
validation_steps=len(test_dt)
As you can see the val_accuracy is not better than 0.5000, which is very bad!
And now if you just change the last layer to model.add(Dense(2, activation='sigmoid')) and run the same model with 2 nodes in the last layer, you will end up with a far better result, such as val_accuracy: 0.8680.
How should know, how many nodes should I have in the last layer when I have a binary-classification model?
Thanks to #Dr.Snoopy, i add an answer here jut to complete the question.
The point is how do we label our data using the image_data_generator.flow_from_directory().
If we set the class_mode='categorical' then the target is ONE_HOT and the number of nodes in the last layer is equal to "number of classes of target feature". In my case, it is a binary feature, so i need to have 2 nodes in the last layer.
However, if we use class_mode='binary' then the target is indexed and we can have only one node in the last layer.
Related
I am currently studying how CNNs can be used in text classification and found some code on stack overflow that had worked with the use of a keras embedding layer.
I ran the code with the keras embedding but now want to test out what would happen with a pre-trained embedding, I have downloaded the word2vec api from gensim but dont know how to adapt the code from there?
My question is how can I replace the keras embedding layer with a pre-trained embedding like the word2vec model or Glove?
heres is the code
from keras.datasets import imdb
from keras.models import Sequential
from keras.layers import Dense
from keras.layers import LSTM, Convolution1D, Flatten, Dropout
from keras.layers.embeddings import Embedding
from keras.preprocessing import sequence
from keras.callbacks import TensorBoard
# Using keras to load the dataset with the top_words
top_words = 10000
(X_train, y_train), (X_test, y_test) = imdb.load_data(num_words=top_words)
# Pad the sequence to the same length
max_review_length = 1600
X_train = sequence.pad_sequences(X_train, maxlen=max_review_length)
X_test = sequence.pad_sequences(X_test, maxlen=max_review_length)
# Using embedding from Keras
embedding_vecor_length = 300
model = Sequential()
model.add(Embedding(top_words, embedding_vecor_length, input_length=max_review_length))
# Convolutional model (3x conv, flatten, 2x dense)
model.add(Convolution1D(64, 3, padding='same'))
model.add(Convolution1D(32, 3, padding='same'))
model.add(Convolution1D(16, 3, padding='same'))
model.add(Flatten())
model.add(Dropout(0.2))
model.add(Dense(180,activation='sigmoid'))
model.add(Dropout(0.2))
model.add(Dense(1,activation='sigmoid'))
# Log to tensorboard
tensorBoardCallback = TensorBoard(log_dir='./logs', write_graph=True)
model.compile(loss='binary_crossentropy', optimizer='adam', metrics=['accuracy'])
model.fit(X_train, y_train, epochs=3, callbacks=[tensorBoardCallback], batch_size=64)
# Evaluation on the test set
scores = model.evaluate(X_test, y_test, verbose=0)
print("Accuracy: %.2f%%" % (scores[1]*100))
This reads the text file containing the weights, stores the words and their weights in a dictionary, then maps them into a new matrix using the vocabulary of your fit tokenizer.
from keras.datasets import imdb
from keras.models import Sequential
from keras.layers import Dense
from keras.layers import LSTM, Convolution1D, Flatten, Dropout
from keras.layers.embeddings import Embedding
from keras.preprocessing import sequence
from keras.callbacks import TensorBoard
from tensorflow import keras
import itertools
import numpy as np
# Using keras to load the dataset with the top_words
top_words = 10000
(X_train, y_train), (X_test, y_test) = imdb.load_data(num_words=top_words)
word_index = keras.datasets.imdb.get_word_index()
embedding_vecor_length = 300 # same as the embeds to be loaded below
embeddings_dictionary = dict()
glove_file = open('./embeds/glove.6B.300d.txt', 'rb')
for line in glove_file:
records = line.split() # seperates each line by a white space
word = records[0] # the first element is the word
vector_dimensions = np.asarray(
records[1:], dtype='float32') # the rest are the weights
# storing in dictionary
embeddings_dictionary[word] = vector_dimensions
glove_file.close()
# len_of_vocab = len(word_index)
embeddings_matrix = np.zeros((top_words, embedding_vecor_length))
# mapping to a new matrix, using only the words in your tokenizer's vocabulary
for word, index in word_index.items():
if index>=top_words:
continue
# the weights of the individual words in your vocabulary
embedding_vector = embeddings_dictionary.get(bytes(word, 'utf-8'))
if embedding_vector is not None:
embeddings_matrix[index] = embedding_vector
# Pad the sequence to the same length
max_review_length = 1600
X_train = sequence.pad_sequences(X_train, maxlen=max_review_length)
X_test = sequence.pad_sequences(X_test, maxlen=max_review_length)
# Using embedding from Keras
model = Sequential()
model.add(Embedding(top_words, embedding_vecor_length,
input_length=max_review_length, name="embeddinglayer", weights=[embeddings_matrix], trainable=True))
# Convolutional model (3x conv, flatten, 2x dense)
model.add(Convolution1D(64, 3, padding='same'))
model.add(Convolution1D(32, 3, padding='same'))
model.add(Convolution1D(16, 3, padding='same'))
model.add(Flatten())
model.add(Dropout(0.2))
model.add(Dense(180, activation='sigmoid'))
model.add(Dropout(0.2))
model.add(Dense(1, activation='sigmoid'))
# Log to tensorboard
tensorBoardCallback = TensorBoard(log_dir='./logs', write_graph=True)
model.compile(loss='binary_crossentropy',
optimizer='adam', metrics=['accuracy'])
model.fit(X_train, y_train, epochs=3, callbacks=[
tensorBoardCallback], batch_size=64)
# Evaluation on the test set
scores = model.evaluate(X_test, y_test, verbose=0)
print("Accuracy: %.2f%%" % (scores[1]*100))
I've created sound classifier build using Keras from some tutorials in the internet. Here is my model code
import tensorflow as tf
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Dense, InputLayer, Dropout, Conv1D, Conv2D, Flatten, Reshape, MaxPooling1D, MaxPooling2D, BatchNormalization, TimeDistributed
from tensorflow.keras.optimizers import Adam
model = Sequential()
model.add(Reshape((int(input_length / 40), 40), input_shape=(input_length, )))
model.add(Conv1D(8, kernel_size=3, activation='relu', padding='same'))
model.add(MaxPooling1D(pool_size=2, strides=2, padding='same'))
model.add(Dropout(0.25))
model.add(Conv1D(16, kernel_size=3, activation='relu', padding='same'))
model.add(MaxPooling1D(pool_size=2, strides=2, padding='same'))
model.add(Dropout(0.25))
model.add(Flatten())
model.add(Dense(classes, activation='softmax', name='y_pred'))
opt = Adam(lr=0.005, beta_1=0.9, beta_2=0.999)
# this controls the batch size, or you can manipulate the tf.data.Dataset objects yourself
BATCH_SIZE = 32
train_dataset = train_dataset.batch(BATCH_SIZE, drop_remainder=False)
validation_dataset = validation_dataset.batch(BATCH_SIZE, drop_remainder=False)
model.compile(loss='categorical_crossentropy', optimizer=opt, metrics=['accuracy'])
model.fit(train_dataset, epochs=1000, validation_data=validation_dataset, verbose=2, callbacks=callbacks)
My teacher ask me what is algorithm I use for classifying (he said something like K-NN, Naive Bayes, SVM or something like that), and I don't know what I'm using.
You're using a Convolutional Neural Network (CNN)
so I'm new right here and in Python also. I'm trying to make my own network. I found some pictures of docs and cats 15x15 and unfortunatly couldn't make this basic network...
So, these are libraries which I'm using
from tensorflow.keras.models import Sequential
from tensorflow.keras import utils
from tensorflow.keras.datasets import mnist
from tensorflow.keras.layers import Dense
import numpy as np
import matplotlib.pyplot as plt
import tensorflow as tf
import keras
from tensorflow.keras.layers import Conv2D
from tensorflow.keras.layers import MaxPooling2D
from tensorflow.keras.layers import GlobalMaxPooling2D
Body
train_dataset = tf.keras.preprocessing.image_dataset_from_directory(
'drive/MyDrive/cats vs dogs/cats vs dogs/training',
color_mode="rgb",
batch_size=32,
image_size=(150, 150),
shuffle=True,
seed=42,
validation_split=0.1,
subset='training',
interpolation="bilinear",
follow_links=False,
)
validation_dataset = tf.keras.preprocessing.image_dataset_from_directory(
'drive/MyDrive/cats vs dogs/cats vs dogs/training',
color_mode="rgb",
batch_size=32,
image_size=(150, 150),
shuffle=True,
seed=42,
validation_split=0.1,
subset='validation',
interpolation="bilinear",
follow_links=False,
)
test_dataset = tf.keras.preprocessing.image_dataset_from_directory(
'drive/MyDrive/cats vs dogs/cats vs dogs/test',
batch_size = 32,
image_size = (150, 150),
interpolation="bilinear"
)
model = Sequential()
model.add(keras.Input(shape=(150, 150, 3)))
model.add(Conv2D(32, 5, strides=2, activation="relu"))
model.add(Conv2D(32, 3, activation="relu"))
model.add(MaxPooling2D(3))
model.add(Dense(250, activation='sigmoid'))
model.add(Dense(100))
model.add(MaxPooling2D(3))
model.add(Dense(2))
model.summary()
model.compile(loss='binary_crossentropy',
optimizer='adam',
metrics=['accuracy'])
history = model.fit(train_dataset, validation_data=validation_dataset, epochs=5, verbose=2)
And I get this error
Incompatible shapes: [29] vs. [29,7,7,2]
[[node gradient_tape/binary_crossentropy/mul_1/BroadcastGradientArgs
(defined at /usr/local/lib/python3.7/dist-packages/keras/optimizer_v2/optimizer_v2.py:464)
]] [Op:__inference_train_function_4364]
Errors may have originated from an input operation.
Input Source operations connected to node
gradient_tape/binary_crossentropy/mul_1/BroadcastGradientArgs:
In[0] gradient_tape/binary_crossentropy/mul_1/Shape:
In[1] gradient_tape/binary_crossentropy/mul_1/Shape_1
I was trying to change from binary_crossentropy to categorical_crossentrapy but it didn't help, I suppose my mistake is in datasets or inputs but I don't know how to solve it :(
Really hope to find help here!
[my architecture][1]
[1]: https://i.stack.imgur.com/w4Y9N.png
You need to flatten your prediction somewhere, otherwise you are outputing an image (29 samples of size 7x7 with 2 channels), while you simply want a flat 2 dimensional logits (so shape 29x2). The architecture you are using is somewhat odd, did you mean to have flattening operation before first Dense layer, and then no "maxpooling2d" (as it makes no sense for flattened signal)? Mixing relu and sigmoid activations is also quite non standard, I would encourage you to start with established architectures rather than try to compose your own to get some intuitions.
model = Sequential()
model.add(keras.Input(shape=(150, 150, 3)))
model.add(Conv2D(32, 5, strides=2, activation="relu"))
model.add(Conv2D(32, 3, activation="relu"))
model.add(MaxPooling2D(3))
model.add(Flatten())
model.add(Dense(250, activation="relu"))
model.add(Dense(100, activation="relu"))
model.add(Dense(2))
model.summary()
I am trying to build a image classification model, using ImageDataGenerator().
It seems that the model trains and performs poorly. The training loss stays at around 15 and the accuracy is barely 10%, the validation is about the same.
Just to see what would happen, I tried training without using the ImageDataGenerator() and set up the data in a similar way. It performed much better in training, validation and testing. With training loss of 0.71 and accuracy of 75% and validation loss of 0.8 and accuracy of 72%.
I need to figure out this model with the data generator because I will be moving on to a larger dataset, where it will not fit into memory.
So, I guess my question is what am I doing wrong with the ImageDataGenerator() that it is performing so badly and how can I improve the outcome?
When setting up the files (in all Train, Test, Validation folders), there are the classes with its own folder and in those folders is where the images are.
Here is the code:
import tensorflow as tf
from tensorflow.keras.preprocessing.image import ImageDataGenerator
import pickle
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Dense, Activation, Flatten, Conv2D, MaxPooling2D, Dropout
data_gen = ImageDataGenerator()
IMG_SIZE = 100
train_it = data_gen.flow_from_directory('D:/.../Train/', class_mode='sparse',
target_size=(IMG_SIZE, IMG_SIZE),color_mode='grayscale', shuffle=True,batch_size=32)
val_it = data_gen.flow_from_directory('D:/.../Validation/', class_mode='sparse',
target_size=(IMG_SIZE, IMG_SIZE),color_mode='grayscale', shuffle=True,batch_size=32)
IMAGE_SIZE = [100, 100]
model=Sequential()
model.add(Conv2D(32,(3,3), input_shape=[*IMAGE_SIZE, 1]))
model.add(Activation('relu'))
model.add(MaxPooling2D(pool_size=(2,2)))
model.add(Dropout(0.5))
model.add(Conv2D(32,(3,3)))
model.add(Activation('relu'))
model.add(MaxPooling2D(pool_size=(2,2)))
model.add(Dropout(0.5))
model.add(Conv2D(32,(3,3)))
model.add(Activation('relu'))
model.add(MaxPooling2D(pool_size=(2,2)))
model.add(Dropout(0.5))
model.add(Flatten())
model.add(Dense(len(train_it.class_indices), activation='softmax'))
model.compile(loss='sparse_categorical_crossentropy', optimizer='adam', metrics=['accuracy'])
model.fit_generator(train_it, epochs=20, validation_data=val_it )
Here is my code without ImageDataGenerator():
SETUP the data, using OpenCV
DATADIR='D:\...\Train'
CATEGORIES = pickle.load(open("CATEGORIES.p" , "rb"))
print(len(CATEGORIES))
IMG_SIZE = 100
training_data=[]
def create_training_data():
for category in CATEGORIES:
path = os.path.join(DATADIR,category)
class_num = CATEGORIES.index(category)
for img in os.listdir(path):
try:
img_array = cv2.imread(os.path.join(path,img),cv2.IMREAD_GRAYSCALE)
new_array = cv2.resize(img_array, (IMG_SIZE, IMG_SIZE))
training_data.append([new_array, class_num])
except:
print(category)
print(img)
create_training_data()
random.shuffle(training_data)
X=[]
y=[]
for features, label in training_data:
X.append(features)
y.append(label)
X=np.array(X).reshape(-1,IMG_SIZE, IMG_SIZE, 1)
X=X/255.0
MODEL SETUP:
model=Sequential()
model.add(Conv2D(32,(3,3), input_shape=[*IMAGE_SIZE, 1]))
model.add(Activation('relu'))
model.add(MaxPooling2D(pool_size=(2,2)))
model.add(Dropout(0.5))
model.add(Conv2D(32,(3,3)))
model.add(Activation('relu'))
model.add(MaxPooling2D(pool_size=(2,2)))
model.add(Dropout(0.5))
model.add(Conv2D(32,(3,3)))
model.add(Activation('relu'))
model.add(MaxPooling2D(pool_size=(2,2)))
model.add(Dropout(0.5))
model.add(Flatten())
model.add(Dense(len(CATEGORIES), activation='softmax'))
model.compile(loss='sparse_categorical_crossentropy', optimizer='adam', metrics=['accuracy'])
model.fit(X,y, epochs=20, batch_size=32, validation_split=0.1)
#acho,
Mentioning the solution to this issue cited by you in the comments, for the benefit of the community.
Reason for the issue is that Input Data is not Normalized by dividing each Pixel Value by 255. It has an impact on Training because of the reasons mentioned below:
It converts Pixel Values from Integers to Float, in a range of 0.0-1.0 where 0.0 means 0 (0x00) and 1.0 means 255 (0xFF). Conv Nets work better on Float Values compared to Integer Values, and by normalizing it in a range of 0-1, computations will be reduced.
Normalization will help you to remove distortions caused by lights and shadows in an image.
I have a data base with this shape: (1400000, 44)
which the 44th column is output.
all numbers are float and between 0 and 1. I used a Tensorflow like below but the loss function is non and the acc is zero.
# Create network with Keras
import tensorflow as tf
from keras.models import Sequential
from keras.layers import Dense
import numpy as np
dataset=np.loadtxt("Dataset5.txt")
s=dataset.size
tr_size=int( 0.7*s)
X = dataset[0:tr_size,0:43]
Y = dataset[0:tr_size,43]
# create model
model = Sequential()
model.add(Dense(64, input_dim=43, init='uniform', activation='relu'))
model.add(Dense(16, init='uniform', activation='relu'))
model.add(Dense(4, init='uniform', activation='sigmoid'))
model.add(Dense(1, init='uniform', activation='relu'))
# Compile model
model.compile(loss='mean_squared_error', optimizer='adam', metrics=['accuracy'])
# Fit the model
model.fit(X, Y, epochs=150, batch_size=1000, verbose=2)
# calculate predictions
predictions = model.predict(X)