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  • How to Fix Cost Function in Binary Classification NAN as a Result in Python

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    I am quite new to both python and machine learning and I am trying to create an ANN for a binary classification model in order to determine whether something is faulty or not. When I run the code down below, the cost function seem to come up as nan. Unfortunately, in order to come up with an accuracy percentage, I need the cost to be an actual number. Is there an obvious error in my code or is there another way to circumvent this problem by writing it differently? Any help will be much appreciated.




    import csv  
    import tensorflow as tf  
    import numpy as np  
    import pandas as pd  
    import urllib.request as request  
    import matplotlib.pyplot as plt  
    train_data = pd.read_csv("C:/Python35/train_data.csv", sep=',', header = None)  
    test_data = pd.read_csv("C:/Python35/test_data.csv", sep=',', header = None)  
    X_train = np.asarray(train_data)  
    X_test = np.asarray(test_data)  
    train_label = pd.read_csv("C:/Python35/train_label.csv", sep=',', header = None)  
    test_label = pd.read_csv("C:/Python35/test_label.csv", sep=',', header = None)  
    y_train = np.asarray(train_label)  
    y_test = np.asarray(test_label)  
    labels_train = (np.arange(2) == y_train[:,None]).astype(np.float32)  
    labels_test = (np.arange(2) == y_test[:,None]).astype(np.float32)  
    inputs = tf.placeholder(tf.float32, shape=(None, X_train.shape[1]), name='inputs')  
    label = tf.placeholder(tf.float32, shape=(None, 2), name='labels')  
    hid1_size = 128  
    w1 = tf.Variable(tf.random_normal([hid1_size, X_train.shape[1]], stddev=0.01), name='w1')  
    b1 = tf.Variable(tf.constant(0.1, shape=(hid1_size, 1)), name='b1')  
    y1 = tf.nn.dropout(tf.nn.relu(tf.add(tf.matmul(w1, tf.transpose(inputs)), b1)),  keep_prob=0.5)
    hid2_size = 256  
    w2 = tf.Variable(tf.random_normal([hid2_size, hid1_size], stddev=0.01), name='w2')  
    b2 = tf.Variable(tf.constant(0.1, shape=(hid2_size, 1)), name='b2')  
    y2 = tf.nn.dropout(tf.nn.relu(tf.add(tf.matmul(w2, y1), b2)), keep_prob=0.5)  
    wo = tf.Variable(tf.random_normal([2, hid2_size], stddev=0.01), name='wo')  
    bo = tf.Variable(tf.random_normal([2, 1]), name='bo')  
    yo = tf.transpose(tf.add(tf.matmul(wo, y2), bo))  
    lr = tf.placeholder(tf.float32, shape=(), name='learning_rate')  
    loss = tf.reduce_mean(tf.nn.softmax_cross_entropy_with_logits(logits=yo, labels=label))  
    optimizer = tf.train.GradientDescentOptimizer(lr).minimize(loss)  
    pred = tf.nn.softmax(yo)  
    pred_label = tf.argmax(pred, 1)  
    correct_prediction = tf.equal(tf.argmax(pred, 1), tf.argmax(label, 1))  
    accuracy = tf.reduce_mean(tf.cast(correct_prediction, "float"))  
    init = tf.global_variables_initializer()  
    config = tf.ConfigProto()  
    config.gpu_options.allow_growth = True  
    sess = tf.InteractiveSession(config=config)  
    for learning_rate in [0.05, 0.01]:  
        for epoch in range(50):  
            avg_cost = 0.0  
            for i in range(X_train.shape[0]):  
                _, c =[optimizer, loss], feed_dict={lr:learning_rate,  
                                                              inputs: X_train[i, None],  
                                                              label: labels_train[i, None].reshape(-1,2)})  
                avg_cost += c  
            avg_cost /= X_train.shape[0]      
            if epoch % 10 == 0:  
                print("Epoch: {:3d}    Train Cost: {:.4f}".format(epoch, avg_cost))  
    acc_train = accuracy.eval(feed_dict={inputs: X_train, label: labels_train.reshape(-1,2)})  
    print("Train accuracy: {:3.2f}%".format(acc_train*100.0))  
    acc_test = accuracy.eval(feed_dict={inputs: X_test, label: labels_test.reshape(-1,2)})  
    print("Test accuracy:  {:3.2f}%".format(acc_test*100.0))  

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