pyarrow.NativeFile

class pyarrow.NativeFile

Bases: _Weakrefable

The base class for all Arrow streams.

Streams are either readable, writable, or both. They optionally support seeking.

While this class exposes methods to read or write data from Python, the primary intent of using a Arrow stream is to pass it to other Arrow facilities that will make use of it, such as Arrow IPC routines.

Be aware that there are subtle differences with regular Python files, e.g. destroying a writable Arrow stream without closing it explicitly will not flush any pending data.

__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.
get_stream(self, file_offset, nbytes)	Return an input stream that reads a file segment independent of the state of the file.
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])	NOT IMPLEMENTED.
readlines(self[, hint])	NOT IMPLEMENTED.
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])	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.

get_stream(self, file_offset, nbytes)

Return an input stream that reads a file segment independent of the state of the file.

Allows reading portions of a random access file as an input stream without interfering with each other.

Parameters:

file_offsetint

nbytesint

Returns:

streamNativeFile

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)

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”.

Parameters:

sizeint

maximum number of bytes read

readlines(self, hint=None)

NOT IMPLEMENTED. Read lines of the file

Parameters:

hintint

maximum number of bytes read until we stop

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)

NOT IMPLEMENTED

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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