Tensorflow Neural Network for Binary Classicication; how do I use placeholder - machine-learning

Question

Here is my code:
My target is a vector with shape(N,) which is a vector with only binary numbers
However, I'm running into compiling errors
/Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6 /Users/Lai/Dropbox/PersonalProject/MachineLearningForSports/models/NeuralNetwork.py
/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/sklearn/cross_validation.py:44: DeprecationWarning: This module was deprecated in version 0.18 in favor of the model_selection module into which all the refactored classes and functions are moved. Also note that the interface of the new CV iterators are different from that of this module. This module will be removed in 0.20.
"This module will be removed in 0.20.", DeprecationWarning)
Traceback (most recent call last):
File "/Users/Lai/Dropbox/PersonalProject/MachineLearningForSports/models/NeuralNetwork.py", line 102, in <module>
_, c = sess.run([optimizer,cost],feed_dict = {x:batch_x,y:batch_y})
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/tensorflow/python/client/session.py", line 766, in run
run_metadata_ptr)
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/tensorflow/python/client/session.py", line 943, in _run
% (np_val.shape, subfeed_t.name, str(subfeed_t.get_shape())))
ValueError: Cannot feed value of shape (100,) for Tensor 'Placeholder_1:0', which has shape '(?, 2)'
Since my batch size is 100; I believe that the error is at when comparing my target to my predictions. The tf.placable seems make the prediction with N*2, although I'm sure. Any help ?? Thanks
import tensorflow as tf
import DataPrepare as dp
import numpy as np
def random_init(x,num_feature_1st,num_feature_2nd,num_class):
W1 = tf.Variable(tf.random_normal([num_feature_1st,num_feature_2nd]))
bias1 = tf.Variable(tf.random_normal([num_feature_2nd]))
W2 = tf.Variable(tf.random_normal([num_feature_2nd,num_class]))
bias2 = tf.Variable(tf.random_normal([num_class]))
return [W1,bias1,W2,bias2]
def softsign(z):
"""The softsign function, applied elementwise."""
return z / (1. + np.abs(z))
def multilayer_perceptron(x,num_feature_1st,num_feature_2nd,num_class):
params = random_init(x,num_feature_1st,num_feature_2nd,num_class)
layer_1 = tf.add(tf.matmul(x,params[0]),params[1])
layer_1 = softsign(layer_1)
#layer_1 = tf.nn.relu(layer_1)
layer_2 = tf.add(tf.matmul(layer_1,params[2]),params[3])
#output = tf.nn.softmax(layer_2)
output = tf.nn.sigmoid(layer_2)
return output
def next_batch(num, dataX,dataY):
idx = np.arange(0,len(dataX))
np.random.shuffle(idx)
idx = idx[0:num]
dataX_shuffle = [dataX[i] for i in idx]
dataY_shuffle = [dataY[i] for i in idx]
dataX_shuffle = np.asarray(dataX_shuffle)
dataY_shuffle = np.asarray(dataY_shuffle)
return dataX_shuffle, dataY_shuffle
if __name__ == "__main__":
#sess = tf.InteractiveSession()
learning_rate = 0.001
training_epochs = 10
batch_size = 100
display_step = 1
num_feature_1st = 6
num_feature_2nd = 500
num_class = 2
x = tf.placeholder('float', [None, 6])
y = tf.placeholder('float',[None,2])
data = dp.dataPrepare(dp.datas,dp.path)
trainX = data[0]
testX = data[1] # a matrix
trainY = data[2] # a vector with binary number
testY = data[3]
params = random_init(x,num_feature_1st,num_feature_2nd,num_class)
# construct model
pred = multilayer_perceptron(x, num_feature_1st, num_feature_2nd, num_class)
cost = tf.reduce_mean(tf.nn.sigmoid_cross_entropy_with_logits(pred, y))
optimizer = tf.train.AdamOptimizer().minimize(cost)
init = tf.global_variables_initializer()
with tf.Session() as sess:
sess.run(init)
#train
for epoch in range(training_epochs):
avg_cost = 0
total_batch = int(len(trainX[:,0])/batch_size)
for i in range(total_batch):
batch_x, batch_y = next_batch(batch_size,trainX,trainY)
_, c = sess.run([optimizer,cost],feed_dict = {x:batch_x,y:batch_y})
avg_cost += c/total_batch
if epoch % display_step ==0:
print("Epoch: ", "%04d" % (epoch+1), " cost= ", "{:.9f}".format(avg_cost))
print("Optimization Finished!")

Answer 1

Whenever you execute a dynamic node from the computation graph - which is pretty much any node that is not an input - you need to specify all dependent variables. Think about this this way: If you had a mathematical function of the form
y = f(x) = Ax + b (for example)
and you wanted to evaluate that function, you need to specify x as well. You need not, however, specify x if you wanted to evaluate (i.e. read) the value of A, since A is known (at least in this context).
Consequently, you can evaluate (by passing it to tf.Session.run(...) the parameters of your network without specifying the inputs (A in the example above). You cannot, however, evaluate the output of your functions without specifying the inputs (in the example, you need to specify x).
As for your code, the following line will thus not work:
print(sess.run(pred)), since you ask the session to evaluate a function without specifying its inputs.