# chainer.dataset.concat_examples¶

chainer.dataset.concat_examples(batch, device=None, padding=None)[source]

Concatenates a list of examples into array(s).

Dataset iterator yields a list of examples. If each example is an array, this function concatenates them along the newly-inserted first axis (called batch dimension) into one array. The basic behavior is same for examples consisting of multiple arrays, i.e., corresponding arrays of all examples are concatenated.

For instance, consider each example consists of two arrays (x, y). Then, this function concatenates x ‘s into one array, and y ‘s into another array, and returns a tuple of these two arrays. Another example: consider each example is a dictionary of two entries whose keys are 'x' and 'y', respectively, and values are arrays. Then, this function concatenates x ‘s into one array, and y ‘s into another array, and returns a dictionary with two entries x and y whose values are the concatenated arrays.

When the arrays to concatenate have different shapes, the behavior depends on the padding value. If padding is None (default), it raises an error. Otherwise, it builds an array of the minimum shape that the contents of all arrays can be substituted to. The padding value is then used to the extra elements of the resulting arrays.