pyarrow.PythonFile

class pyarrow.PythonFile

Bases: NativeFile

A stream backed by a Python file object.

This class allows using Python file objects with arbitrary Arrow functions, including functions written in another language than Python.

As a downside, there is a non-zero redirection cost in translating Arrow stream calls to Python method calls. Furthermore, Python’s Global Interpreter Lock may limit parallelism in some situations.

__init__(*args, **kwargs)

Methods

__init__(*args, **kwargs)
close(self)
download(self, stream_or_path[, buffer_size])	Read this file completely to a local path or destination stream.
fileno(self)	NOT IMPLEMENTED
flush(self)	Flush the stream, if applicable.
isatty(self)
metadata(self)	Return file metadata
read(self[, nbytes])	Read and return up to n bytes.
read1(self[, nbytes])	Read and return up to n bytes.
read_at(self, nbytes, offset)	Read indicated number of bytes at offset from the file
read_buffer(self[, nbytes])
readable(self)
readall(self)
readinto(self, b)	Read into the supplied buffer
readline(self[, size])
readlines(self[, hint])
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[, pos])
upload(self, stream[, buffer_size])	Write from a source stream to this file.
writable(self)
write(self, data)	Write data to the file.
writelines(self, lines)

Attributes

closed
mode	The file mode.

close(self)

closed

download(self, stream_or_path, buffer_size=None)

Read this file completely to a local path or destination stream.

This method first seeks to the beginning of the file.

Parameters:

stream_or_pathstr or file-like object

If a string, a local file path to write to; otherwise, should be a writable stream.

buffer_sizeint, optional

The buffer size to use for data transfers.

fileno(self)

NOT IMPLEMENTED

flush(self)

Flush the stream, if applicable.

An error is raised if stream is not writable.

isatty(self)

metadata(self)

Return file metadata

mode

The file mode. Currently instances of NativeFile may support:

• rb: binary read

• wb: binary write

• rb+: binary read and write

read(self, nbytes=None)

Read and return up to n bytes.

If nbytes is None, then the entire remaining file contents are read.

Parameters:

nbytesint, default None

Returns:

databytes

read1(self, nbytes=None)

Read and return up to n bytes.

Unlike read(), if nbytes is None then a chunk is read, not the entire file.

Parameters:

nbytesint, default None

The maximum number of bytes to read.

Returns:

databytes

read_at(self, nbytes, offset)

Read indicated number of bytes at offset from the file

Parameters:

nbytesint

offsetint

Returns:

databytes

read_buffer(self, nbytes=None)

readable(self)

readall(self)

readinto(self, b)

Read into the supplied buffer

Parameters:

bbuffer-like object

A writable buffer object (such as a bytearray).

Returns:

writtenint

number of bytes written

readline(self, size=None)

readlines(self, hint=None)

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

Change current file stream position

Parameters:

positionint

Byte offset, interpreted relative to value of whence argument

whenceint, default 0

Point of reference for seek offset

Returns:

int

The new absolute stream position.

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

seekable(self)

size(self)

Return file size

tell(self)

Return current stream position

truncate(self, pos=None)

upload(self, stream, buffer_size=None)

Write from a source stream to this file.

Parameters:

streamfile-like object

Source stream to pipe to this file.

buffer_sizeint, optional

The buffer size to use for data transfers.

writable(self)

write(self, data)

Write data to the file.

Parameters:

databytes-like object or exporter of buffer protocol

Returns:

int

nbytes: number of bytes written

writelines(self, lines)

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