pyarrow.MemoryMappedFile

class pyarrow.MemoryMappedFile

Bases: pyarrow.lib.NativeFile

A stream that represents a memory-mapped file.

Supports ‘r’, ‘r+’, ‘w’ modes.

__init__()

Initialize self. See help(type(self)) for accurate signature.

Methods

close(self)
create(path, size)
download(self, stream_or_path[, buffer_size])	Read file completely to local path (rather than reading completely into memory).
fileno(self)
flush(self)	Flush the buffer stream, if applicable.
isatty(self)
read(self[, nbytes])	Read indicated number of bytes from file, or read all remaining bytes if no argument passed
read1(self[, nbytes])	Read and return up to n bytes.
read_buffer(self[, nbytes])
readable(self)
readall(self)
readinto(self, b)	Read into the supplied buffer
readline(self[, size])	NOT IMPLEMENTED.
readlines(self[, hint])	NOT IMPLEMENTED.
resize(self, new_size)	Resize the map and underlying file.
seek(self, int64_t position, int whence=0)	Change current file stream position
seekable(self)
size(self)	Return file size
tell(self)	Return current stream position
truncate(self)	NOT IMPLEMENTED
upload(self, stream[, buffer_size])	Pipe file-like object to file
writable(self)
write(self, data)	Write byte from any object implementing buffer protocol (bytes, bytearray, ndarray, pyarrow.Buffer)
writelines(self, lines)

Attributes

closed
mode	binary read * wb: binary write * rb+: binary read and write

close(self)

closed

static create(path, size)

download(self, stream_or_path, buffer_size=None)

Read file completely to local path (rather than reading completely into memory). First seeks to the beginning of the file.

fileno(self)

flush(self)

Flush the buffer stream, if applicable.

No-op to match the IOBase interface.

isatty(self)

mode

binary read * wb: binary write * rb+: binary read and write

Type:

The file mode. Currently instances of NativeFile may support

Type:

• rb

read(self, nbytes=None)

Read indicated number of bytes from file, or read all remaining bytes if no argument passed

Parameters:nbytes (int, default None) – Returns:data (bytes)

read1(self, nbytes=None)

Read and return up to n bytes.

Alias for read, needed to match the IOBase interface.

read_buffer(self, nbytes=None)

readable(self)

readall(self)

readinto(self, b)

Read into the supplied buffer

Parameters:b (any python object supporting buffer interface) – Returns:number of bytes written

readline(self, size=None)

NOT IMPLEMENTED. Read and return a line of bytes from the file.

If size is specified, read at most size bytes.

Line terminator is always b”n”.

readlines(self, hint=None)

NOT IMPLEMENTED. Read lines of the file

Parameters:hint (int maximum number of bytes read until we stop) –

resize(self, new_size)

Resize the map and underlying file.

Parameters:new_size (new size in bytes) –

seek(self, int64_t position, int whence=0)

Change current file stream position

Parameters:

• position (int) – Byte offset, interpreted relative to value of whence argument
• whence (int, default 0) – Point of reference for seek offset

Notes

Values of whence: * 0 – start of stream (the default); offset should be zero or positive * 1 – current stream position; offset may be negative * 2 – end of stream; offset is usually negative

Returns:new_position (the new absolute stream position)

seekable(self)

size(self)

Return file size

tell(self)

Return current stream position

truncate(self)

NOT IMPLEMENTED

upload(self, stream, buffer_size=None)

Pipe file-like object to file

writable(self)

write(self, data)

Write byte from any object implementing buffer protocol (bytes, bytearray, ndarray, pyarrow.Buffer)

Parameters:data (bytes-like object or exporter of buffer protocol) – Returns:nbytes (number of bytes written)

writelines(self, lines)