python-pype

pype: command-line pipes in Python ####################################

Usage

Basics

At the command prompt, use ``pype`` to act on each item in the file with python commands: ::

  $ pype map x.upper() <<<'abc'
  ABC


Chain python functions together with ``!``: ::

  $ pype map 'x.upper() ! len(x)' <<<hello
  5

or by adding another command like  ``map <pipeline>`` ::

   $ pype map 'x.upper()' map 'len(x)' <<<hello
   5


Use ``x`` as a placeholder for the input at each stage: ::

  $ pype map ' x.split()[0] ! x.upper() + "!"' <<<'Hello world'
  HELLO!

  $ pype map 'x.split()[0] ! x.upper() + "!" ! x.replace("H", "J")' <<<'Hello world'
  JELLO!



Automatically import modules you need: ::

   $ pype stack 'itertools.repeat(x, 2) ! "".join' <<<hello,world!
   hello,world!
   hello,world!



Commands

map

---

Use map to act on each input item. ::

$ pype map 'x * 2' <<<'a\nbb\n' aa bbbb

filter

---

Use filter to evaluate a condition on each line of input and exclude false values. ::

$ pype filter 'len(x) > 1' <<<'a\nbb\nccc\n' bb ccc

apply

---

Use apply to act on the sequence of items. ::

$   pype apply 'len(x)' <<<'a\nbb\n'
2

stack

---

Use stack to treat the input as a single string, including newlines. ::

$  pype stack 'len(x)' <<<'a\nbb\n'
5

Use eval to evaluate a python expression without any input. ::

$ pype eval 1+1 2

reduce

---

Use reduce to evaluate a function of two arguments successively over a sequence, like functools.reduce <https://docs.python.org/3/library/functools.html#functools.reduce>_.

For example, to multiply all the values together, first convert each value to int with map, then use reduce to successively multiply each item with the product. ::

$ pype map int reduce operator.mul <<EOF 1 2 3 4 EOF

24

Autocall

You don't need to explicitly call the function with ``f(x)``; just use ``f``. For example, instead of ::

  $ pype map 'len(x)' <<<'a\nbb'
  5

try ::

  $ pype map len <<<'a\nbb'
  5



Async
~~~~~

Making sequential requests is slow. These requests take 20 seconds to complete. ::

   $ time pype map 'requests.get ! x.text ! len' apply max <<EOF
   http://httpbin.org/delay/5
   http://httpbin.org/delay/1
   http://httpbin.org/delay/4
   http://httpbin.org/delay/3
   http://httpbin.org/delay/4
   EOF

   302

   0.61s user
   0.06s system
   19.612 total

Concurrent requests can go much faster. The same requests now take only 6 seconds. Use ``amap``, or ``afilter``, or ``reduce`` with ``await some_async_function`` to get concurrency out of the box. ::

   $ time pype amap 'await asks.get ! x.text ! len' apply max <<EOF
   http://httpbin.org/delay/5
   http://httpbin.org/delay/1
   http://httpbin.org/delay/4
   http://httpbin.org/delay/3
   http://httpbin.org/delay/4
   EOF

   297

   0.57s user
   0.08s system
   5.897 total


Async streaming

amap and afilter values are handled in streaming fashion, while retaining the order of the input items in the output. The order of function calls is not constrained -- if you need the function to be called with items in a specific order, use the synchronous version.

Making concurrent requests, each response is printed one at a time, as soon as (1) it is ready and (2) all of the preceding requests have already been handled.

For example, the 3 seconds item is ready before the preceding 4 seconds item, but it is held until the 4 seconds is ready because 4 seconds was started first, so the ordering of the input items is maintained in the output.

::

$ time pype --exec-before 'import datetime; now=datetime.datetime.utcnow; START_TIME=now(); print("Elapsed time | Response size")' map 'await asks.get !  f"{(now() - START_TIME).seconds} seconds    | {len(x.content)} bytes"'  <<EOF
http://httpbin.org/delay/1
http://httpbin.org/delay/2
http://httpbin.org/delay/4
http://httpbin.org/delay/3
EOF
Elapsed time | Response size
1 seconds    | 297 bytes
2 seconds    | 297 bytes
4 seconds    | 297 bytes
3 seconds    | 297 bytes

Configuration

Add code to automatically execute, into your config file.

For example: ::

  # ~/.config/pype/config.toml

  exec_before = """

  from itertools import *
  from collections import Counter

  """

Then you can directly use the imported objects without referencing the module. ::


    $ pype map 'Counter ! json.dumps' <<<'hello\nworld\n'
    {"h": 1, "e": 1, "l": 2, "o": 1}
    {"w": 1, "o": 1, "r": 1, "l": 1, "d": 1}


You can set any of the ``pype`` options in your config. For example, to set a different default value for the concurrency maximum ``pype --max-concurrent``, add ``max_concurrent`` to your config file (note the underscore): ::

  # ~/.config/pype/config.toml

  max_concurrent = 10

then just use ``pype`` as normal.



Aliases

Define new commands in your config file which provide aliases to other commands. For example, this config adds a jsonl command for reading jsonlines streams into Python objects, by calling calling out to the map traversal. ::

[[alias]]

name = "jsonl" short_help = "Load jsonlines into python objects."

[[alias.stage]]

command = "map" options = [] arguments = [ "json.loads ! types.SimpleNameSpace(**x)" ]

Now we can use it like a regular command: ::

$ pype jsonl  <<< $'{"a":1, "b":2}\n{"a": 5, "b":9}'
X(a=1, b=2)
X(a=5, b=9)

The new command jsonl can be used in pipelines as well. To get the maximum value in a sequence of jsonlines objects. ::

$ pype jsonl map 'x.a' apply max <<< $'{"a":1, "b":2}\n{"a": 5, "b":9}' 5

Plugins

Add new commands like ``map`` and ``reduce`` by installing pype plugins. You can try them out without installing by adding them to any ``.py`` file in your ``~/.config/pype/modules/``.


Installation
============

Get it with pip: ::

   pip install python-pype


Caveats
=======


* ``pype`` assumes *trusted command arguments* and *untrusted input stream data*. It uses ``eval`` on your commands, not on the input stream data. If you use ``exec``, ``eval``, ``subprocess``, or similar commands, you can execute arbitrary code from the input stream, like in regular python.


Status
======

* Check the `issues page <https://www.github.com/python-pype/pype/issues>`_ for open tickets.
* This package is experimental and is subject to change without notice.


Related work
============

* https://github.com/Russell91/pythonpy
* http://gfxmonk.net/dist/doc/piep/
* https://spy.readthedocs.io/en/latest/intro.html
* https://github.com/ksamuel/Pyped
* https://github.com/ircflagship2/pype