def standardize(X):
    X_std = X
    mean = X.mean(axis=0)
    std = X.std(axis=0)
    for col in range(np.shape(X)[1]):
        if std[col]:
            X_std[:, col] = ((X_std[:, col] - mean[col]) / std[col])
    return X_std
def standardize(X):
    X_std = X
    mean = X.mean(axis=0)
    std = X.std(axis=0)
    for col in range(np.shape(X)[1]):
        if std[col]:
            X_std[:, col] = ((X_std[:, col] - mean[col]) / std[col])
    return X_std