Answers for "Logistic Regression with a Neural Network mindset python example"

Logistic Regression with a Neural Network mindset python example

print ("sigmoid([0, 2]) = " + str(sigmoid(np.array([0,2]))))

Logistic Regression with a Neural Network mindset python example

- m_train (number of training examples)
- m_test (number of test examples)
- num_px (= height = width of a training image)

Logistic Regression with a Neural Network mindset python example

def load_dataset():
    train_dataset = h5py.File('datasets/train_catvnoncat.h5', "r")
    train_set_x_orig = np.array(train_dataset["train_set_x"][:]) # your train set features
    train_set_y_orig = np.array(train_dataset["train_set_y"][:]) # your train set labels

    test_dataset = h5py.File('datasets/test_catvnoncat.h5', "r")
    test_set_x_orig = np.array(test_dataset["test_set_x"][:]) # your test set features
    test_set_y_orig = np.array(test_dataset["test_set_y"][:]) # your test set labels

    classes = np.array(test_dataset["list_classes"][:]) # the list of classes
    
    train_set_y_orig = train_set_y_orig.reshape((1, train_set_y_orig.shape[0]))
    test_set_y_orig = test_set_y_orig.reshape((1, test_set_y_orig.shape[0]))
    
    return train_set_x_orig, train_set_y_orig, test_set_x_orig, test_set_y_orig, classes

Logistic Regression with a Neural Network mindset python example

train_set_x = train_set_x_flatten/255.
test_set_x = test_set_x_flatten/255.

Logistic Regression with a Neural Network mindset python example

dim = 2
w, b = initialize_with_zeros(dim)
print ("w = " + str(w))
print ("b = " + str(b))

Logistic Regression with a Neural Network mindset python example

sigmoid([0, 2]) = [ 0.5         0.88079708]

Logistic Regression with a Neural Network mindset python example

X_flatten = X.reshape(X.shape[0], -1).T      # X.T is the transpose of X

Logistic Regression with a Neural Network mindset python example

- a training set of m_train images labeled as cat (y=1) or non-cat (y=0)
- a test set of m_test images labeled as cat or non-cat
- each image is of shape (num_px, num_px, 3) where 3 is for the 3 channels (RGB). Thus, each image is square (height = num_px) and (width = num_px).

Logistic Regression with a Neural Network mindset python example

y = [1], it's a 'cat' picture.

Logistic Regression with a Neural Network mindset python example

- Initialize the parameters of the model
- Learn the parameters for the model by minimizing the cost  
- Use the learned parameters to make predictions (on the test set)
- Analyse the results and conclude