Python re.search vs re.sub Post: 302965355

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Top Forums Programming Python re.search vs re.sub Post 302965355 by metallica1973 on Wednesday 27th of January 2016 05:58:34 PM

01-27-2016

Registered User

Python re.search vs re.sub

I am having trouble understanding why these two commands differ with one producing the desire results and the other not. An example:

Code:

capture_str = 'xserver-xorg-video-qxl-dbg (0.1.1-2+b2 [s390x], 0.1.1-2+b1 [amd64, armel, armhf, i386, mips, mipsel, powerpc], 0.1.1-2 [arm64, ppc64el]) X.Org X server -- QXL display driver (debugging symbols)'

re.search(r'(?<=\[s390x\]\, ).*', capture_str).group(0)
'0.1.1-2+b1 [amd64, armel, armhf, i386, mips, mipsel, powerpc], 0.1.1-2 [arm64, ppc64el]) X.Org X server -- QXL display driver (debugging symbols)'

re.sub(r'(?<=\[s390x\]\, ).*', '', capture_str)
'xserver-xorg-video-qxl-dbg (0.1.1-2+b2 [s390x], '

I am truly confused at why "re.sub" doesnt perform a positive lookbehind that re.search can do. It appears to be doing the opposite with the same regex. What is the difference?

Last edited by metallica1973; 01-27-2016 at 07:11 PM..

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LEARN ABOUT DEBIAN

empy

EMPY(1) 						      General Commands Manual							   EMPY(1)

NAME

       empy -  A powerful and robust templating system for Python

SYNOPSIS

       empy [options] [<filename, or  '-' for stdin>  [<argument>]]

DESCRIPTION

       This manual page documents briefly the empy command.

       EmPy is a system for embedding Python expressions and statements in template text; it takes an EmPy source file, processes it, and produces
       output. This is accomplished via expansions, which are special signals to the EmPy system and are set off by a special prefix  (by  default
       the at sign, @).

       EmPy can expand arbitrary Python expressions and statements in this way, as well as a variety of special forms. Textual data not explicitly
       delimited in this way is sent unaffected to the output, allowing Python to be used in effect as a markup language. Also supported are call-
       backs  via hooks, recording and playback via diversions, and dynamic, chainable filters. The system is highly configurable via command line
       options and embedded commands.

OPTIONS

       These programs follow the usual GNU command line syntax, with long options starting with  two  dashes  (`-').   A  summary  of  options	is
       included below.	For a complete description, see the Info files.

       -h, --help
	      Show summary of options.

       -v, --version
	      Show version of program.

SEE ALSO

       python(1).

AUTHOR

       EmPy was written by Erik Max Francis <software@alcyone.com>.

       This manual page was written by Ana Beatriz Guerrero Lopez, for the Debian project (but may be used by others).

																	   EMPY(1)