linalg:stack

(linalg:stack arrays &key axis)

Joins the arrays in the list arrays along a new axis (numpy's np.stack). Every input must have exactly the same shape; the result has one more axis, of extent (length arrays), inserted at :axis (default 0, negative counting from the end of the result, so -1 appends it). The result is a fresh array with the first input's element width. This is how a list of per-sample arrays becomes one batch array; to join along an axis that already exists, use linalg:concatenate.