問題描述

假設我有兩個相同長度的列表:

Lets say I have two lists of same length:

a = ['a1', 'a2', 'a3']
b = ['b1', 'b2', 'b3']

我想生成以下字符串:

c = 'a1=b1, a2=b2, a3=b3'

實現這一目標的最佳方法是什么?

What is the best way to achieve this?

我有以下實現:

import timeit

a = [str(f) for f in range(500)]
b = [str(f) for f in range(500)]

def func1():
    return ', '.join([aa+'='+bb for aa in a for bb in b if a.index(aa) == b.index(bb)])

def func2():
    list = []
    for i in range(len(a)):
        list.append('%s=%s' % (a[i], b[i]))
    return ', '.join(list)

t = timeit.Timer(setup='from __main__ import func1', stmt='func1()')
print 'func1 = ' + t.timeit(10) 

t = timeit.Timer(setup='from __main__ import func2', stmt='func2()')
print 'func2 = ' + t.timeit(10)

輸出是:

func1 = 32.4704790115
func2 = 0.00529003143311

你有一些權衡嗎?

推薦答案

a = ['a1', 'a2', 'a3']
b = ['b1', 'b2', 'b3']

pat = '%s=%%s, %s=%%s, %s=%%s'

print pat % tuple(a) % tuple(b)

給出 a1=b1, a2=b2, a3=b3

.

然后:

from timeit import Timer
from itertools import izip

n = 300

a = [str(f) for f in range(n)]
b = [str(f) for f in range(n)]

def func1():
    return ', '.join([aa+'='+bb for aa in a for bb in b if a.index(aa) == b.index(bb)])

def func2():
    list = []
    for i in range(len(a)):
        list.append('%s=%s' % (a[i], b[i]))
    return ', '.join(list)

def func3():
    return ', '.join('%s=%s' % t for t in zip(a, b))

def func4():
    return ', '.join('%s=%s' % t for t in izip(a, b))

def func5():
    pat = n * '%s=%%s, '
    return pat % tuple(a) % tuple(b)

d = dict(zip((1,2,3,4,5),('heavy','append','zip','izip','% formatting')))
for i in xrange(1,6):
    t = Timer(setup='from __main__ import func%d'%i, stmt='func%d()'%i)
    print 'func%d = %s  %s' % (i,t.timeit(10),d[i])

結果

func1 = 16.2272833558  heavy
func2 = 0.00410247671143  append
func3 = 0.00349569568199  zip
func4 = 0.00301686387516  izip
func5 = 0.00157338432678  % formatting

這篇關于將兩個列表加入格式化字符串的最聰明方法的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！