numpy.lib.format.open_memmap#

lib.format.open_memmap(filename, mode='r+', dtype=None, shape=None, fortran_order=False, version=None, *, max_header_size=10000)[source]#

Open a .npy file as a memory-mapped array.

This may be used to read an existing file or create a new one.

Parameters:

filenamestr or path-like: The name of the file on disk. This may not be a file-like object.
modestr, optional: The mode in which to open the file; the default is ‘r+’. In addition to the standard file modes, ‘c’ is also accepted to mean “copy on write.” See memmap for the available mode strings.
dtypedata-type, optional: The data type of the array if we are creating a new file in “write” mode, if not, dtype is ignored. The default value is None, which results in a data-type of float64.
shapetuple of int: The shape of the array if we are creating a new file in “write” mode, in which case this parameter is required. Otherwise, this parameter is ignored and is thus optional.
fortran_orderbool, optional: Whether the array should be Fortran-contiguous (True) or C-contiguous (False, the default) if we are creating a new file in “write” mode.
versiontuple of int (major, minor) or None: If the mode is a “write” mode, then this is the version of the file format used to create the file. None means use the oldest supported version that is able to store the data. Default: None
max_header_sizeint, optional: Maximum allowed size of the header. Large headers may not be safe to load securely and thus require explicitly passing a larger value. See ast.literal_eval for details.

Returns:

marraymemmap: The memory-mapped array.

Raises:

ValueError: If the data or the mode is invalid.
OSError: If the file is not found or cannot be opened correctly.