LossFunction.py 文件源码

def crossEntropy(x):
    """Cross entropy loss function. Only works for networks with one output."""

    if x.ndim == 1:
        pass

    elif x.ndim == 2:
        x = x[:, 0]

    else:
        raise ValueError('x must be either a vector or a matrix.')

    y = tt.vector('y')
    L = -tt.mean(y * tt.log(x) + (1-y) * tt.log(1-x))
    L.name = 'loss'

    return y, L