Pythonic方式写两个if语句

Question

I have two variables that are the result of regex searches.

a = re.search('some regex', str)
b = re.search('different regex', str)

This should return a re object. If they are not None, I want to use the group() method to get the string that it matched. This is the code I am using right now to do this:

if a != None:
   a = a.group()
if b != None:
   b = b.group()

Is there a more clever way to write these two if-statements? Maybe combine them into one? I think taking up 4 lines to do this is too verbose.

Thanks.

Answer 1

Don't shadow the built-in str , and say

if a:

instead of

if a != None

Not much else to improve imho.

Answer 2

a = a.group() if a else None

Answer 3

如果你真的必须有一个单行：

a, b = a.group() if a else None, b.group() if b else None

Answer 4

As I commented, I prefer not to reuse a and b for both the Match object and the matched text. I'd go with a function to pull out the match, like this:

>>> def text_or_none(v): return v.group() if v is not None else None
>>> a = text_or_none(re.search("\d", "foo"))
None
>>> b = text_or_none(re.search("\w+", "foo"))
foo

Answer 5

You can refactor little:

a, b = (var.group() if var is not None else None for var in (a,b) )

This keeps value of a if it is for example 0. This is the end of your request.

However after some time passed I came up with this suggestion considering context:

import re
target = """"Id","File","Easting","Northing","Alt","Omega","Phi","Kappa","Photo","Roll","Line","Roll_line","Orient","Camera"
1800,2008308_017_079.tif,530658.110,5005704.180,2031.100000,0.351440,-0.053710,0.086470,79,2008308,17,308_17,rightX,Jen73900229d
"""
print target
regs=(',(.*.tif)',',(left.*)',',(right.*)')
re_results=(result.group()
            for result in ((re.search(reg, target)
                            for reg in regs)
                           )
            if result is not None)
print list(re_results)