numpy.concatenate — NumPy v1.15 Manual (original) (raw)
numpy. concatenate((a1, a2, ...), axis=0, out=None)¶
Join a sequence of arrays along an existing axis.
| Parameters: | a1, a2, … : sequence of array_like The arrays must have the same shape, except in the dimension corresponding to axis (the first, by default). axis : int, optional The axis along which the arrays will be joined. If axis is None, arrays are flattened before use. Default is 0. out : ndarray, optional If provided, the destination to place the result. The shape must be correct, matching that of what concatenate would have returned if no out argument were specified. |
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| Returns: | res : ndarray The concatenated array. |
See also
Concatenate function that preserves input masks.
Split an array into multiple sub-arrays of equal or near-equal size.
Split array into a list of multiple sub-arrays of equal size.
Split array into multiple sub-arrays horizontally (column wise)
Split array into multiple sub-arrays vertically (row wise)
Split array into multiple sub-arrays along the 3rd axis (depth).
Stack a sequence of arrays along a new axis.
Stack arrays in sequence horizontally (column wise)
Stack arrays in sequence vertically (row wise)
Stack arrays in sequence depth wise (along third dimension)
Notes
When one or more of the arrays to be concatenated is a MaskedArray, this function will return a MaskedArray object instead of an ndarray, but the input masks are not preserved. In cases where a MaskedArray is expected as input, use the ma.concatenate function from the masked array module instead.
Examples
a = np.array([[1, 2], [3, 4]]) b = np.array([[5, 6]]) np.concatenate((a, b), axis=0) array([[1, 2], [3, 4], [5, 6]]) np.concatenate((a, b.T), axis=1) array([[1, 2, 5], [3, 4, 6]]) np.concatenate((a, b), axis=None) array([1, 2, 3, 4, 5, 6])
This function will not preserve masking of MaskedArray inputs.
a = np.ma.arange(3) a[1] = np.ma.masked b = np.arange(2, 5) a masked_array(data = [0 -- 2], mask = [False True False], fill_value = 999999) b array([2, 3, 4]) np.concatenate([a, b]) masked_array(data = [0 1 2 2 3 4], mask = False, fill_value = 999999) np.ma.concatenate([a, b]) masked_array(data = [0 -- 2 2 3 4], mask = [False True False False False False], fill_value = 999999)