PYLINER - SCRIPT TO RUN ARBITRARY PYTHON CODE ON THE COMMAND LINE (PYTHON RECIPE)

Created by Drew Gulino as a recipe on ActiveState, the recipe has now been ported to 577075_Pyliner__Script_run_arbitrary_Pythcode. This project aims to make the recipe more accessible.

A Python script that runs arbitrary Python scripts in an input loop. This allows one-liner Python scripts similarly to how Perl runs them (-l,-a,-n,-F, BEGIN, END)

It provides additional syntax that allows multiline Python scripts to be run on a single line

I work on *nix systems and use one-liner bash+awk+sed+etc.. scripts all the time, but I find I need Perl for some features. But I prefer and remember Python better. There are a few other scripts that allow something like Perl's cool one-liner '-lane', 'BEGIN' ,'END', etc, but don't have the full functionality.

This script is based on http://code.activestate.com/recipes/437932-pyline-a-grep-like-sed-like-command-line-tool/ (Graham Fawcett + Jacob Oscarson, Mark Eichin) and Perl. It attempts to provide all the one-liner functionality that Perl provides. G.F., J.O., and M.E.'s original recipe is now hosted at 437932_Pyline_greplike_sedlike_commandline

To get this to work, I had to create some additional syntax to allow Python to run on a single line without tabs. I understand this goes against much of what Python 'stands' for, but I'm pragmatic. This is no PEP to modify the language or a critique of Python's syntax; I just like the language and want to use it in an area that it's not well adapted for.

Usage:

pyliner (options) "script"

options

-a enables auto-split of input into the F[] array.

-F specifies the characters to split on with the -a option (default=" ").

-p loops over and prints input.

-n loops over and does not print input.

-l strips newlines on input, and adds them on output.

-M lets you specify module imports.

-o print out parsed and indented script on multiple lines.

-e (assumed - does nothing, added for Perl compatibility).

script

";" specify newlines

":" will start an indent for the following lines

"?;" will add a newline and dedent the following lines

"/;" will reset the indent the far left

"BEGIN:" starts the an initial script not run in the input loop

"END:" starts part of the script run after the input loop

"#/" ends both the "BEGIN:" and "END:" portions of the script

variables

F[] = split input

line = current input line

NR = current input line number

functions

I(x) = function returns F[x] cast to integer

f(x) = function returns F[x] cast to float

Examples

test.txt:

10,test
1,rest
100,test
10,best
1000,we
1,see

Example 1:

Return the sum of numbers in the first column that are greater than 90:

cat test.txt | ./pyline.py -F"," -lane \
'BEGIN:sum=0#/if i(0) > 90:sum+=i(0)) END:print sum#/'

output:

1100

Example 2:

pyliner

cat test.txt | ./pyliner.py -F"," -lane \
'BEGIN:sum=0#/a=f(0);if a > 90:sum+=a END:print sum/NR#/'

output:

183.333333333

perl:

cat test.txt | perl -F"," -lane \
'BEGIN {$sum=0; } ;$sum=$sum+=@F[0] if @F[0]>90;END { print $sum/$.; }'

output:

183.333333333333

Example 3:

Chunk average (average of every N amount of numbers in a pipe):

echo -en "1\n 2\n 3\n 4\n 10\n 10\n 10\n 10\n" | ./pyliner.py -lane -F"," \
'BEGIN:s=0;n=4#/s+=f(0);if not NR % n:print s/n;s=0'

output:

2.5
10.0

License

This program is licensed under the GNU V3 license. See LICENSE.md for the full text.