"compression.zstd" --- Compression compatible with the Zstandard format
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"compression.zstd" --- Compression compatible with the Zstandard format#
Added in version 3.14.
Source code: Lib/compression/zstd/init.py
======================================================================
This module provides classes and functions for compressing and decompressing data using the Zstandard (or zstd) compression algorithm. The zstd manual describes Zstandard as "a fast lossless compression algorithm, targeting real-time compression scenarios at zlib-level and better compression ratios." Also included is a file interface that supports reading and writing the contents of ".zst" files created by the zstd utility, as well as raw zstd compressed streams.
The "compression.zstd" module contains:
-
The "open()" function and "ZstdFile" class for reading and writing compressed files.
-
The "ZstdCompressor" and "ZstdDecompressor" classes for incremental (de)compression.
-
The "compress()" and "decompress()" functions for one-shot (de)compression.
-
The "train_dict()" and "finalize_dict()" functions and the "ZstdDict" class to train and manage Zstandard dictionaries.
-
The "CompressionParameter", "DecompressionParameter", and "Strategy" classes for setting advanced (de)compression parameters.
This is an optional module. If it is missing from your copy of CPython, look for documentation from your distributor (that is, whoever provided Python to you). If you are the distributor, see Requirements for optional modules.
Exceptions#
exception compression.zstd.ZstdError
This exception is raised when an error occurs during compression or decompression, or while initializing the (de)compressor state.
Reading and writing compressed files#
compression.zstd.open(file, /, mode='rb', *, level=None, options=None, zstd_dict=None, encoding=None, errors=None, newline=None)
Open a Zstandard-compressed file in binary or text mode, returning a file object.
The file argument can be either a file name (given as a "str", "bytes" or path-like object), in which case the named file is opened, or it can be an existing file object to read from or write to.
The mode argument can be either "'rb'" for reading (default), "'wb'" for overwriting, "'ab'" for appending, or "'xb'" for exclusive creation. These can equivalently be given as "'r'", "'w'", "'a'", and "'x'" respectively. You may also open in text mode with "'rt'", "'wt'", "'at'", and "'xt'" respectively.
When reading, the options argument can be a dictionary providing advanced decompression parameters; see "DecompressionParameter" for detailed information about supported parameters. The zstd_dict argument is a "ZstdDict" instance to be used during decompression. When reading, if the level argument is not None, a "TypeError" will be raised.
When writing, the options argument can be a dictionary providing advanced compression parameters; see "CompressionParameter" for detailed information about supported parameters. The level argument is the compression level to use when writing compressed data. Only one of level or options may be non-None. The zstd_dict argument is a "ZstdDict" instance to be used during compression.
In binary mode, this function is equivalent to the "ZstdFile" constructor: "ZstdFile(file, mode, ...)". In this case, the encoding, errors, and newline parameters must not be provided.
In text mode, a "ZstdFile" object is created, and wrapped in an "io.TextIOWrapper" instance with the specified encoding, error handling behavior, and line endings.
class compression.zstd.ZstdFile(file, /, mode='rb', *, level=None, options=None, zstd_dict=None)
Open a Zstandard-compressed file in binary mode.
A "ZstdFile" can wrap an already-open file object, or operate directly on a named file. The file argument specifies either the file object to wrap, or the name of the file to open (as a "str", "bytes" or path-like object). If wrapping an existing file object, the wrapped file will not be closed when the "ZstdFile" is closed.
The mode argument can be either "'rb'" for reading (default), "'wb'" for overwriting, "'xb'" for exclusive creation, or "'ab'" for appending. These can equivalently be given as "'r'", "'w'", "'x'" and "'a'" respectively.
If file is a file object (rather than an actual file name), a mode of "'w'" does not truncate the file, and is instead equivalent to "'a'".
When reading, the options argument can be a dictionary providing advanced decompression parameters; see "DecompressionParameter" for detailed information about supported parameters. The zstd_dict argument is a "ZstdDict" instance to be used during decompression. When reading, if the level argument is not None, a "TypeError" will be raised.
When writing, the options argument can be a dictionary providing advanced compression parameters; see "CompressionParameter" for detailed information about supported parameters. The level argument is the compression level to use when writing compressed data. Only one of level or options may be passed. The zstd_dict argument is a "ZstdDict" instance to be used during compression.
"ZstdFile" supports all the members specified by "io.BufferedIOBase", except for "detach()" and "truncate()". Iteration and the "with" statement are supported.
The following method and attributes are also provided:
peek(size=-1)
Return buffered data without advancing the file position. At
least one byte of data will be returned, unless EOF has been
reached. The exact number of bytes returned is unspecified (the
*size* argument is ignored).
Nota:
While calling "peek()" does not change the file position of
the "ZstdFile", it may change the position of the underlying
file object (for example, if the "ZstdFile" was constructed by
passing a file object for *file*).
mode
"'rb'" for reading and "'wb'" for writing.
name
The name of the Zstandard file. Equivalent to the "name"
attribute of the underlying *file object*.
Compressing and decompressing data in memory#
compression.zstd.compress(data, level=None, options=None, zstd_dict=None)
Compress data (a bytes-like object), returning the compressed data as a "bytes" object.
The level argument is an integer controlling the level of compression. level is an alternative to setting "CompressionParameter.compression_level" in options. Use "bounds()" on "compression_level" to get the values that can be passed for level. If advanced compression options are needed, the level argument must be omitted and in the options dictionary the "CompressionParameter.compression_level" parameter should be set.
The options argument is a Python dictionary containing advanced compression parameters. The valid keys and values for compression parameters are documented as part of the "CompressionParameter" documentation.
The zstd_dict argument is an instance of "ZstdDict" containing trained data to improve compression efficiency. The function "train_dict()" can be used to generate a Zstandard dictionary.
compression.zstd.decompress(data, zstd_dict=None, options=None)
Decompress data (a bytes-like object), returning the uncompressed data as a "bytes" object.
The options argument is a Python dictionary containing advanced decompression parameters. The valid keys and values for compression parameters are documented as part of the "DecompressionParameter" documentation.
The zstd_dict argument is an instance of "ZstdDict" containing trained data used during compression. This must be the same Zstandard dictionary used during compression.
If data is the concatenation of multiple distinct compressed frames, decompress all of these frames, and return the concatenation of the results.
class compression.zstd.ZstdCompressor(level=None, options=None, zstd_dict=None)
Create a compressor object, which can be used to compress data incrementally.
For a more convenient way of compressing a single chunk of data, see the module-level function "compress()".
The level argument is an integer controlling the level of compression. level is an alternative to setting "CompressionParameter.compression_level" in options. Use "bounds()" on "compression_level" to get the values that can be passed for level. If advanced compression options are needed, the level argument must be omitted and in the options dictionary the "CompressionParameter.compression_level" parameter should be set.
The options argument is a Python dictionary containing advanced compression parameters. The valid keys and values for compression parameters are documented as part of the "CompressionParameter" documentation.
The zstd_dict argument is an optional instance of "ZstdDict" containing trained data to improve compression efficiency. The function "train_dict()" can be used to generate a Zstandard dictionary.
compress(data, mode=ZstdCompressor.CONTINUE)
Compress *data* (a *bytes-like object*), returning a "bytes"
object with compressed data if possible, or otherwise an empty
"bytes" object. Some of *data* may be buffered internally, for
use in later calls to "compress()" and "flush()". The returned
data should be concatenated with the output of any previous
calls to "compress()".
The *mode* argument is a "ZstdCompressor" attribute, either
"CONTINUE", "FLUSH_BLOCK", or "FLUSH_FRAME".
When all data has been provided to the compressor, call the
"flush()" method to finish the compression process. If
"compress()" is called with *mode* set to "FLUSH_FRAME",
"flush()" should not be called, as it would write out a new
empty frame.
flush(mode=ZstdCompressor.FLUSH_FRAME)
Finish the compression process, returning a "bytes" object
containing any data stored in the compressor's internal buffers.
The *mode* argument is a "ZstdCompressor" attribute, either
"FLUSH_BLOCK", or "FLUSH_FRAME".
set_pledged_input_size(size)
Specify the amount of uncompressed data *size* that will be
provided for the next frame. *size* will be written into the
frame header of the next frame unless
"CompressionParameter.content_size_flag" is "False" or "0". A
size of "0" means that the frame is empty. If *size* is "None",
the frame header will omit the frame size. Frames that include
the uncompressed data size require less memory to decompress,
especially at higher compression levels.
If "last_mode" is not "FLUSH_FRAME", a "ValueError" is raised as
the compressor is not at the start of a frame. If the pledged
size does not match the actual size of data provided to
"compress()", future calls to "compress()" or "flush()" may
raise "ZstdError" and the last chunk of data may be lost.
After "flush()" or "compress()" are called with mode
"FLUSH_FRAME", the next frame will not include the frame size
into the header unless "set_pledged_input_size()" is called
again.
CONTINUE
Collect more data for compression, which may or may not generate
output immediately. This mode optimizes the compression ratio by
maximizing the amount of data per block and frame.
FLUSH_BLOCK
Complete and write a block to the data stream. The data returned
so far can be immediately decompressed. Past data can still be
referenced in future blocks generated by calls to "compress()",
improving compression.
FLUSH_FRAME
Complete and write out a frame. Future data provided to
"compress()" will be written into a new frame and *cannot*
reference past data.
last_mode
The last mode passed to either "compress()" or "flush()". The
value can be one of "CONTINUE", "FLUSH_BLOCK", or "FLUSH_FRAME".
The initial value is "FLUSH_FRAME", signifying that the
compressor is at the start of a new frame.
class compression.zstd.ZstdDecompressor(zstd_dict=None, options=None)
Create a decompressor object, which can be used to decompress data incrementally.
For a more convenient way of decompressing an entire compressed stream at once, see the module-level function "decompress()".
The options argument is a Python dictionary containing advanced decompression parameters. The valid keys and values for compression parameters are documented as part of the "DecompressionParameter" documentation.
The zstd_dict argument is an instance of "ZstdDict" containing trained data used during compression. This must be the same Zstandard dictionary used during compression.
Nota:
This class does not transparently handle inputs containing
multiple compressed frames, unlike the "decompress()" function
and "ZstdFile" class. To decompress a multi-frame input, you
should use "decompress()", "ZstdFile" if working with a *file
object*, or multiple "ZstdDecompressor" instances.
decompress(data, max_length=-1)
Decompress *data* (a *bytes-like object*), returning
uncompressed data as bytes. Some of *data* may be buffered
internally, for use in later calls to "decompress()". The
returned data should be concatenated with the output of any
previous calls to "decompress()".
If *max_length* is non-negative, the method returns at most
*max_length* bytes of decompressed data. If this limit is
reached and further output can be produced, the "needs_input"
attribute will be set to "False". In this case, the next call to
"decompress()" may provide *data* as "b''" to obtain more of the
output.
If all of the input data was decompressed and returned (either
because this was less than *max_length* bytes, or because
*max_length* was negative), the "needs_input" attribute will be
set to "True".
Attempting to decompress data after the end of a frame will
raise a "ZstdError". Any data found after the end of the frame
is ignored and saved in the "unused_data" attribute.
eof
"True" if the end-of-stream marker has been reached.
unused_data
Data found after the end of the compressed stream.
Before the end of the stream is reached, this will be "b''".
needs_input
"False" if the "decompress()" method can provide more
decompressed data before requiring new compressed input.
Zstandard dictionaries#
compression.zstd.train_dict(samples, dict_size)
Train a Zstandard dictionary, returning a "ZstdDict" instance. Zstandard dictionaries enable more efficient compression of smaller sizes of data, which is traditionally difficult to compress due to less repetition. If you are compressing multiple similar groups of data (such as similar files), Zstandard dictionaries can improve compression ratios and speed significantly.
The samples argument (an iterable of "bytes" objects), is the population of samples used to train the Zstandard dictionary.
The dict_size argument, an integer, is the maximum size (in bytes) the Zstandard dictionary should be. The Zstandard documentation suggests an absolute maximum of no more than 100 KB, but the maximum can often be smaller depending on the data. Larger dictionaries generally slow down compression, but improve compression ratios. Smaller dictionaries lead to faster compression, but reduce the compression ratio.
compression.zstd.finalize_dict(zstd_dict, /, samples, dict_size, level)
An advanced function for converting a "raw content" Zstandard dictionary into a regular Zstandard dictionary. "Raw content" dictionaries are a sequence of bytes that do not need to follow the structure of a normal Zstandard dictionary.
The zstd_dict argument is a "ZstdDict" instance with the "dict_content" containing the raw dictionary contents.
The samples argument (an iterable of "bytes" objects), contains sample data for generating the Zstandard dictionary.
The dict_size argument, an integer, is the maximum size (in bytes) the Zstandard dictionary should be. See "train_dict()" for suggestions on the maximum dictionary size.
The level argument (an integer) is the compression level expected to be passed to the compressors using this dictionary. The dictionary information varies for each compression level, so tuning for the proper compression level can make compression more efficient.
class compression.zstd.ZstdDict(dict_content, /, *, is_raw=False)
A wrapper around Zstandard dictionaries. Dictionaries can be used to improve the compression of many small chunks of data. Use "train_dict()" if you need to train a new dictionary from sample data.
The dict_content argument (a bytes-like object), is the already trained dictionary information.
The is_raw argument, a boolean, is an advanced parameter controlling the meaning of dict_content. "True" means dict_content is a "raw content" dictionary, without any format restrictions. "False" means dict_content is an ordinary Zstandard dictionary, created from Zstandard functions, for example, "train_dict()" or the external zstd CLI.
When passing a "ZstdDict" to a function, the "as_digested_dict" and "as_undigested_dict" attributes can control how the dictionary is loaded by passing them as the "zstd_dict" argument, for example, "compress(data, zstd_dict=zd.as_digested_dict)". Digesting a dictionary is a costly operation that occurs when loading a Zstandard dictionary. When making multiple calls to compression or decompression, passing a digested dictionary will reduce the overhead of loading the dictionary.
Difference for compression
^^^^^^^^^^^^^^^^^^^^^^^^^^
+------------+----------------+------------+
| | Digested | Undigested |
| | dictionary | dictionary |
|============|================|============|
| Advanced | "window_log", | None |
| parameters | "hash_log", | |
| of the | "chain_log", | |
| compressor | "search_log", | |
| which may | "min_match", | |
| be | "target_lengt | |
| overridden | h", | |
| by the di | "strategy", " | |
| ctionary's | enable_long_d | |
| parameters | istance_match | |
| | ing", "ldm_ha | |
| | sh_log", "ldm | |
| | _min_match", | |
| | "ldm_bucket_s | |
| | ize_log", "ld | |
| | m_hash_rate_l | |
| | og", and some | |
| | non-public | |
| | parameters. | |
+------------+----------------+------------+
| "ZstdDict" | Yes. It's | No. If you |
| internally | faster when | wish to |
| caches the | loading a | load an |
| dictionary | digested | undigested |
| | dictionary | dictionary |
| | again with the | multiple |
| | same | times, |
| | compression | consider |
| | level. | reusing a |
| | | compressor |
| | | object. |
+------------+----------------+------------+
If passing a "ZstdDict" without any attribute, an undigested dictionary is passed by default when compressing and a digested dictionary is generated if necessary and passed by default when decompressing.
dict_content
The content of the Zstandard dictionary, a "bytes" object.
It's the same as the *dict_content* argument in the
"__init__" method. It can be used with other programs, such
as the "zstd" CLI program.
dict_id
Identifier of the Zstandard dictionary, a non-negative int
value.
Non-zero means the dictionary is ordinary, created by
Zstandard functions and following the Zstandard format.
"0" means a "raw content" dictionary, free of any format
restriction, used for advanced users.
Nota:
The meaning of "0" for "ZstdDict.dict_id" is different from
the "dictionary_id" attribute to the "get_frame_info()"
function.
as_digested_dict
Load as a digested dictionary.
as_undigested_dict
Load as an undigested dictionary.
Advanced parameter control#
class compression.zstd.CompressionParameter
An "IntEnum" containing the advanced compression parameter keys that can be used when compressing data.
The "bounds()" method can be used on any attribute to get the valid values for that parameter.
Parameters are optional; any omitted parameter will have its value selected automatically.
Example getting the lower and upper bound of "compression_level":
lower, upper = CompressionParameter.compression_level.bounds()
Example setting the "window_log" to the maximum size:
_lower, upper = CompressionParameter.window_log.bounds()
options = {CompressionParameter.window_log: upper}
compress(b'venezuelan beaver cheese', options=options)
bounds()
Return the tuple of int bounds, "(lower, upper)", of a
compression parameter. This method should be called on the
attribute you wish to retrieve the bounds of. For example, to
get the valid values for "compression_level", one may check the
result of "CompressionParameter.compression_level.bounds()".
Both the lower and upper bounds are inclusive.
compression_level
A high-level means of setting other compression parameters that
affect the speed and ratio of compressing data.
Regular compression levels are greater than "0". Values greater
than "20" are considered "ultra" compression and require more
memory than other levels. Negative values can be used to trade
off faster compression for worse compression ratios.
Setting the level to zero uses "COMPRESSION_LEVEL_DEFAULT".
window_log
Maximum allowed back-reference distance the compressor can use
when compressing data, expressed as power of two, "1 <<
window_log" bytes. This parameter greatly influences the memory
usage of compression. Higher values require more memory but gain
better compression values.
A value of zero causes the value to be selected automatically.
hash_log
Size of the initial probe table, as a power of two. The
resulting memory usage is "1 << (hash_log+2)" bytes. Larger
tables improve compression ratio of strategies <= "dfast", and
improve compression speed of strategies > "dfast".
A value of zero causes the value to be selected automatically.
chain_log
Size of the multi-probe search table, as a power of two. The
resulting memory usage is "1 << (chain_log+2)" bytes. Larger
tables result in better and slower compression. This parameter
has no effect for the "fast" strategy. It's still useful when
using "dfast" strategy, in which case it defines a secondary
probe table.
A value of zero causes the value to be selected automatically.
search_log
Number of search attempts, as a power of two. More attempts
result in better and slower compression. This parameter is
useless for "fast" and "dfast" strategies.
A value of zero causes the value to be selected automatically.
min_match
Minimum size of searched matches. Larger values increase
compression and decompression speed, but decrease ratio. Note
that Zstandard can still find matches of smaller size, it just
tweaks its search algorithm to look for this size and larger.
For all strategies < "btopt", the effective minimum is "4"; for
all strategies > "fast", the effective maximum is "6".
A value of zero causes the value to be selected automatically.
target_length
The impact of this field depends on the selected "Strategy".
For strategies "btopt", "btultra" and "btultra2", the value is
the length of a match considered "good enough" to stop
searching. Larger values make compression ratios better, but
compresses slower.
For strategy "fast", it is the distance between match sampling.
Larger values make compression faster, but with a worse
compression ratio.
A value of zero causes the value to be selected automatically.
strategy
The higher the value of selected strategy, the more complex the
compression technique used by zstd, resulting in higher
compression ratios but slower compression.
Ver también: "Strategy"
enable_long_distance_matching
Long distance matching can be used to improve compression for
large inputs by finding large matches at greater distances. It
increases memory usage and window size.
"True" or "1" enable long distance matching while "False" or "0"
disable it.
Enabling this parameter increases default "window_log" to 128
MiB except when expressly set to a different value. This setting
is enabled by default if "window_log" >= 128 MiB and the
compression strategy >= "btopt" (compression level 16+).
ldm_hash_log
Size of the table for long distance matching, as a power of two.
Larger values increase memory usage and compression ratio, but
decrease compression speed.
A value of zero causes the value to be selected automatically.
ldm_min_match
Minimum match size for long distance matcher. Larger or too
small values can often decrease the compression ratio.
A value of zero causes the value to be selected automatically.
ldm_bucket_size_log
Log size of each bucket in the long distance matcher hash table
for collision resolution. Larger values improve collision
resolution but decrease compression speed.
A value of zero causes the value to be selected automatically.
ldm_hash_rate_log
Frequency of inserting/looking up entries into the long distance
matcher hash table. Larger values improve compression speed.
Deviating far from the default value will likely result in a
compression ratio decrease.
A value of zero causes the value to be selected automatically.
content_size_flag
Write the size of the data to be compressed into the Zstandard
frame header when known prior to compressing.
This flag only takes effect under the following scenarios:
* Calling "compress()" for one-shot compression
* Providing all of the data to be compressed in the frame in a
single "ZstdCompressor.compress()" call, with the
"ZstdCompressor.FLUSH_FRAME" mode.
* Calling "ZstdCompressor.set_pledged_input_size()" with the
exact amount of data that will be provided to the compressor
prior to any calls to "ZstdCompressor.compress()" for the
current frame. "ZstdCompressor.set_pledged_input_size()" must
be called for each new frame.
All other compression calls may not write the size information
into the frame header.
"True" or "1" enable the content size flag while "False" or "0"
disable it.
checksum_flag
A four-byte checksum using XXHash64 of the uncompressed content
is written at the end of each frame. Zstandard's decompression
code verifies the checksum. If there is a mismatch a "ZstdError"
exception is raised.
"True" or "1" enable checksum generation while "False" or "0"
disable it.
dict_id_flag
When compressing with a "ZstdDict", the dictionary's ID is
written into the frame header.
"True" or "1" enable storing the dictionary ID while "False" or
"0" disable it.
nb_workers
Select how many threads will be spawned to compress in parallel.
When "nb_workers" > 0, enables multi-threaded compression, a
value of "1" means "one-thread multi-threaded mode". More
workers improve speed, but also increase memory usage and
slightly reduce compression ratio.
A value of zero disables multi-threading.
job_size
Size of a compression job, in bytes. This value is enforced only
when "nb_workers" >= 1. Each compression job is completed in
parallel, so this value can indirectly impact the number of
active threads.
A value of zero causes the value to be selected automatically.
overlap_log
Sets how much data is reloaded from previous jobs (threads) for
new jobs to be used by the look behind window during
compression. This value is only used when "nb_workers" >= 1.
Acceptable values vary from 0 to 9.
* 0 means dynamically set the overlap amount
* 1 means no overlap
* 9 means use a full window size from the previous job
Each increment halves/doubles the overlap size. "8" means an
overlap of "window_size/2", "7" means an overlap of
"window_size/4", etc.
class compression.zstd.DecompressionParameter
An "IntEnum" containing the advanced decompression parameter keys that can be used when decompressing data. Parameters are optional; any omitted parameter will have its value selected automatically.
The "bounds()" method can be used on any attribute to get the valid values for that parameter.
Example setting the "window_log_max" to the maximum size:
data = compress(b'Some very long buffer of bytes...')
_lower, upper = DecompressionParameter.window_log_max.bounds()
options = {DecompressionParameter.window_log_max: upper}
decompress(data, options=options)
bounds()
Return the tuple of int bounds, "(lower, upper)", of a
decompression parameter. This method should be called on the
attribute you wish to retrieve the bounds of.
Both the lower and upper bounds are inclusive.
window_log_max
The base-two logarithm of the maximum size of the window used
during decompression. This can be useful to limit the amount of
memory used when decompressing data. A larger maximum window
size leads to faster decompression.
A value of zero causes the value to be selected automatically.
class compression.zstd.Strategy
An "IntEnum" containing strategies for compression. Higher-numbered strategies correspond to more complex and slower compression.
Nota:
The values of attributes of "Strategy" are not necessarily stable
across zstd versions. Only the ordering of the attributes may be
relied upon. The attributes are listed below in order.
The following strategies are available:
fast
dfast
greedy
lazy
lazy2
btlazy2
btopt
btultra
btultra2
Miscellaneous#
compression.zstd.get_frame_info(frame_buffer)
Retrieve a "FrameInfo" object containing metadata about a Zstandard frame. Frames contain metadata related to the compressed data they hold.
class compression.zstd.FrameInfo
Metadata related to a Zstandard frame.
decompressed_size
The size of the decompressed contents of the frame.
dictionary_id
An integer representing the Zstandard dictionary ID needed for
decompressing the frame. "0" means the dictionary ID was not
recorded in the frame header. This may mean that a Zstandard
dictionary is not needed, or that the ID of a required
dictionary was not recorded.
compression.zstd.COMPRESSION_LEVEL_DEFAULT
The default compression level for Zstandard: "3".
compression.zstd.zstd_version_info
Version number of the runtime zstd library as a tuple of integers (major, minor, release).
Examples#
Reading in a compressed file:
from compression import zstd
with zstd.open("file.zst") as f: file_content = f.read()
Creating a compressed file:
from compression import zstd
data = b"Insert Data Here" with zstd.open("file.zst", "w") as f: f.write(data)
Compressing data in memory:
from compression import zstd
data_in = b"Insert Data Here" data_out = zstd.compress(data_in)
Incremental compression:
from compression import zstd
comp = zstd.ZstdCompressor() out1 = comp.compress(b"Some data\n") out2 = comp.compress(b"Another piece of data\n") out3 = comp.compress(b"Even more data\n") out4 = comp.flush() # Concatenate all the partial results: result = b"".join([out1, out2, out3, out4])
Writing compressed data to an already-open file:
from compression import zstd
with open("myfile", "wb") as f: f.write(b"This data will not be compressed\n") with zstd.open(f, "w") as zstf: zstf.write(b"This will be compressed\n") f.write(b"Not compressed\n")
Creating a compressed file using compression parameters:
from compression import zstd
options = { zstd.CompressionParameter.checksum_flag: 1 } with zstd.open("file.zst", "w", options=options) as f: f.write(b"Mind if I squeeze in?")