---
layout: post
status: publish
published: true
title: 'Python: Performance Benchmark'
author:
  display_name: 'sipp11'
date: '2013-11-20'
categories:
- coding
tags: python benchmark
---

`[item for sublist in l for item in sublist] is faster than the shortcuts posted so far.

For evidence, as always, you can use the timeit module in the standard library:

    $ python -mtimeit -s'l=[[1,2,3],[4,5,6], [7], [8,9]]*99' '[item for sublist in l for item in sublist]'
    10000 loops, best of 3: 143 usec per loop
    
    $ python -mtimeit -s'l=[[1,2,3],[4,5,6], [7], [8,9]]*99' 'sum(l, [])'
    1000 loops, best of 3: 969 usec per loop
    
    $ python -mtimeit -s'l=[[1,2,3],[4,5,6], [7], [8,9]]*99' 'reduce(lambda x, y: x+y,l)'
    1000 loops, best of 3: 1.1 msec per loop