Python regex match issue and grouping multiple groups

Question

I am trying to parse a command output, which looks like:

2.437 GHz (Channel 6)
Quality=39/70  Signal level=-71 dBm
Encryption key:on
ESSID:"testssid"
IE: IEEE 802.11i/WPA2 Version 1
IE: WPA Version 1

..and essentially convert it to:

channel = 6
quality = "39/70"
signal = -71
encryption = true
essid = "testssid"
wpa = true

I am not particularly good with regular expressions but here's my attempt at extracting these fields:

    m = re.search('Channel (.+)\)', n)
    if m:
            print m.group(1)

    m = re.search('Quality\=(.{5})', n)
    if m:
            print m.group(1)

    m = re.search('level\=(.+)', n)
    if m:
            print m.group(1)

    m = re.search('key\:(.+)', n)
    if m:
            print m.group(1)

    m = re.search('ESSID\:\"(.+?)\"', n)
    if m:
            print m.group(1)

This outputs:

6
39/70
-71 dBm
off
testssid

There are two problems: First one is the 'Quality' value, as I have a hardcoded value that might break if the match is shorter than 5 characters and the second one is the 'signal value', which I rather have without the "dBM" portion. I guess in both cases I'd like to match until the next whitespace character, couldn't get it working with \s though.

Also, having a few re.search operations look cluttered and messy, is there a way to combine these or tidy it up generally?

Thanks.

The problem is that you use always the dot . instead of the appropriate character class (for example [0-9/] for the quality item). With a more descriptive pattern you will gain speed and security. Second thing, if the informations are always in the same order and format, you can try to extract all that you want in a single pattern (use named captures). Or you can try to read your string line by line. (the idea is to avoid to search the full string for each field you need) — Casimir et Hippolyte
– Casimir et Hippolyte, Commented May 21, 2014 at 16:16
@CasimiretHippolyte Thanks for the pointer, I've fixed the code snippet to use appropriate character classes now. — Hamza
– Hamza, Commented May 21, 2014 at 17:10

Joran Beasley · Accepted Answer · 2014-05-21 17:46:37Z

2

re.search('Quality\=(\d+/\d+)', n) #matches a number a slash and a number #/#
re.search('level\=([+-]?\d+)', n) #matches 1 or more numbers so ignore dbm

to clean it up you could do

patterns = {'quality':'Quality\=(\d+/\d+)',
            'level': 'level\=([+-]?\d+)',
            'key':'key\:(.+)',
            'channel':'Channel (.+)\)'}
body_of_text = open("somefile.txt").read()
results = dict([(key,re.search(regex,body_of_text).group(1)) for  key,regex in patterns.items()])
print results

edited May 21, 2014 at 17:46

answered May 21, 2014 at 16:08

Joran Beasley

114k13 gold badges168 silver badges187 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Hamza Over a year ago

Thanks, The regex matches are what I originally wanted them to be with your fixes. Regarding the second bit, I am getting a ValueError: too many values to unpack when I run it, any ideas?

Joran Beasley Over a year ago

yeah I screwed up ... I edited ... it should work now

Collectives™ on Stack Overflow

Python regex match issue and grouping multiple groups

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related