how to replace %s with one variable in python

Question

I have a string like

strTemp='i don\'t want %s repeat the %s variable again %s and again %s'%('aa','aa','aa','aa')

I want to replace all the %s with 'aa', so I have to repeat the 'aa' for many times, how can I tell the program that I want to replace all the %s just with the same variable, so I needn't type the variable for times

Platinum Azure · Accepted Answer · 2012-11-06 01:37:46Z

7

You could use the named formatting argument syntax:

strTemp='i don\'t want %(key)s repeat the %(key)s variable again %(key)s and again %(key)s' % {
    'key': 'replacement value',
}

Not a lot better necessarily since you have to repeat a key four times, but if your replacement value is long, or is a calculation with side effects that you really don't want to do more than once, this is a good option.

answered Nov 6, 2012 at 1:37

Platinum Azure

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Comments

Antimony · Accepted Answer · 2012-11-06 01:38:42Z

7

The % operator is discouraged. Use str.format instead.

strTemp='i don\'t want {0} repeat the {0} variable again {0} and again {0}'.format('aa')

answered Nov 6, 2012 at 1:38

Antimony

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6 Comments

zwol Over a year ago

The {} syntax is newer and spiffier. You can do a bunch of things with it that you can't with the % syntax. And I am under the impression the % syntax was removed from Python 3 but that may be wrong.

Tim Over a year ago

{} is definitely more powerful, but I don't see how that results in % being discouraged.

zwol Over a year ago

@Tim docs.python.org/2/library/stdtypes.html#str.format says "[.format()] is the new standard in Python 3, and should be preferred to the % formatting described in String Formatting Operations in new code."

lynn8570 Over a year ago

Faster than I expected, both the two methods are feasible, and I want to try {} syntax

zwol Over a year ago

@Tim, however, I was mistaken, %-style formatting does still exist in Python 3: docs.python.org/3/library/…

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Don Question · Accepted Answer · 2012-11-06 11:25:59Z

0

if you have really many repetitions and don't want to type {0} or %(var)s you may consider a seldom used (placeholder-)char, which gets replaced, e.g.:

p='µ µµ µµµ µµµµ µµµµµ {1}'.replace('µ','{0}').format(' muahaha ', 'duh')

or for a single substition variable:

strTemp='i don\'t want µ repeat the µ variable again µ and again µ'.replace('µ','aa')

edited Nov 6, 2012 at 11:25

answered Nov 6, 2012 at 1:58

Don Question

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3 Comments

Antimony Over a year ago

For maximum compression and complete unreadability, you can use reduce to chain together lots of replacements with minimal size overhead (only need to specify the function and a list of arguments). I actually wrote a script to compress string literals this way once (it also uses other tricks to reduce size).

Don Question Over a year ago

funny idea! ;-) but i already overstreched the OPs original intention, on the other hand it's never wrong to be reminded of such nice included batteries ;-)

Don Question Over a year ago

@Antimony: btw i use the abilities of my editor (vim) for these superfluous typings: inoremap ¹ {0} inoremap ² {1} .... ;-)

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