chainer.functions.select_item

chainer.functions.select_item(x, t)

Select elements stored in given indices.

This function returns t.choose(x.T), that means y[i] == x[i, t[i]] for all i.

Parameters

• x (Variable or N-dimensional array) – Variable storing arrays. A two-dimensional float array.

• t (Variable or N-dimensional array) – Variable storing index numbers. A one-dimensional int array. Length of the t should be equal to x.shape[0].

Returns

Variable that holds t-th element of x.

Return type

Variable

Example

>>> x = np.array([[0, 1, 2], [3, 4, 5]], np.float32)
>>> t = np.array([0, 2], np.int32)
>>> y = F.select_item(x, t)
>>> y.shape
(2,)
>>> y.array
array([0., 5.], dtype=float32)