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From: Hermann Riemann <nospam.ng@hermann-riemann.de>
Newsgroups: de.comp.lang.python
Subject: Re: [Python-de] strings zusammensetzen.
Date: Wed, 30 Aug 2017 07:26:43 +0200
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Am 29.08.2017 um 17:21 schrieb Walter Dörwald:

> Python 3.6.2 (default, Jul 26 2017, 16:42:24)
> Type 'copyright', 'credits' or 'license' for more information
> IPython 6.1.0 -- An enhanced Interactive Python. Type '?' for help.
> In [1] ▶ base, revision, suffix = "foo", "bar", "baz"
> In [2] ▶ %timeit base + revision + suffix
> 208 ns ± 0.532 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
> In [3] ▶ %timeit '%s%s%s' % (base, revision, suffix)
> 315 ns ± 1.55 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
> In [4] ▶ %timeit '{}{}{}'.format(base, revision, suffix)
> 462 ns ± 1.23 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
> In [5] ▶ %timeit f'{base}{revision}{suffix}'
> 14.6 ns ± 0.00911 ns per loop (mean ± std. dev. of 7 runs, 100000000 
> loops each)

Daraus lese ich:
a+b+c ist schneller als "%s%s%s"%(a,b,c),
"%a%b%c"%(a,b,c) ist schneller als  "{}{}{}".format(a,b,c).

Das mit 14.6 ns ist Hinweis,
das in diesem Fall keine Zwischenwerte der Art (a+b)+c erstellt wurden.

Hermann
    der jetzt wieder eher os.system("rm "+dateiname)
    statt os.system("rm {}".format(dateiname)) schreiben wird.

-- 
http://www.hermann-riemann.de