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Diffstat (limited to 'Doc/library/stdtypes.rst')
| -rw-r--r-- | Doc/library/stdtypes.rst | 38 |
1 files changed, 22 insertions, 16 deletions
diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst index af0a85e..739e90d 100644 --- a/Doc/library/stdtypes.rst +++ b/Doc/library/stdtypes.rst @@ -3282,10 +3282,8 @@ copying. the view. The :class:`~memoryview.itemsize` attribute will give you the number of bytes in a single element. - A :class:`memoryview` supports slicing to expose its data. If - :class:`~memoryview.format` is one of the native format specifiers - from the :mod:`struct` module, indexing will return a single element - with the correct type. Full slicing will result in a subview:: + A :class:`memoryview` supports slicing and indexing to expose its data. + One-dimensional slicing will result in a subview:: >>> v = memoryview(b'abcefg') >>> v[1] @@ -3297,25 +3295,29 @@ copying. >>> bytes(v[1:4]) b'bce' - Other native formats:: + If :class:`~memoryview.format` is one of the native format specifiers + from the :mod:`struct` module, indexing with an integer or a tuple of + integers is also supported and returns a single *element* with + the correct type. One-dimensional memoryviews can be indexed + with an integer or a one-integer tuple. Multi-dimensional memoryviews + can be indexed with tuples of exactly *ndim* integers where *ndim* is + the number of dimensions. Zero-dimensional memoryviews can be indexed + with the empty tuple. + + Here is an example with a non-byte format:: >>> import array >>> a = array.array('l', [-11111111, 22222222, -33333333, 44444444]) - >>> a[0] + >>> m = memoryview(a) + >>> m[0] -11111111 - >>> a[-1] + >>> m[-1] 44444444 - >>> a[2:3].tolist() - [-33333333] - >>> a[::2].tolist() + >>> m[::2].tolist() [-11111111, -33333333] - >>> a[::-1].tolist() - [44444444, -33333333, 22222222, -11111111] - - .. versionadded:: 3.3 - If the underlying object is writable, the memoryview supports slice - assignment. Resizing is not allowed:: + If the underlying object is writable, the memoryview supports + one-dimensional slice assignment. Resizing is not allowed:: >>> data = bytearray(b'abcefg') >>> v = memoryview(data) @@ -3348,12 +3350,16 @@ copying. True .. versionchanged:: 3.3 + One-dimensional memoryviews can now be sliced. One-dimensional memoryviews with formats 'B', 'b' or 'c' are now hashable. .. versionchanged:: 3.4 memoryview is now registered automatically with :class:`collections.abc.Sequence` + .. versionchanged:: 3.5 + memoryviews can now be indexed with tuple of integers. + :class:`memoryview` has several methods: .. method:: __eq__(exporter) |