"""Numpy-related utilities."""
# Taken from Keras

import numpy as np

def to_categorical(y, nb_classes=None):
    """Converts a class vector (integers) to binary class matrix.

    E.g. for use with categorical_crossentropy.

    # Arguments
        y: class vector to be converted into a matrix
            (integers from 0 to nb_classes).
        nb_classes: total number of classes.

    # Returns
        A binary matrix representation of the input.
    """
    y = np.array(y, dtype='int').ravel()
    if not nb_classes:
        nb_classes = np.max(y) + 1
    n = y.shape[0]
    categorical = np.zeros((n, nb_classes))
    categorical[np.arange(n), y] = 1
    return categorical


def categorical_probas_to_classes(p):
    return np.argmax(p, axis=1)


def probas_to_classes(y_pred):
    if len(y_pred.shape) > 1 and y_pred.shape[1] > 1:
        return categorical_probas_to_classes(y_pred)
    return np.array([1 if p > 0.5 else 0 for p in y_pred])

