重新搜索python regexpr

Question

for my assignment I need to search through a program and print out how many pages each user has printed.

date: 2012-11-25
printer on time:  0800 
23.96.82.161 user: pei printer: core 2 pages: 2 code: r n t h p r
28.104.177.80 user: isaac printer: poster pages: 4 code: p h
printer error:  out of paper  time: 1343
180.186.109.129 user: luis printer: core 2 pages: 2 code: k n h
194.96.54.184 user: isaac printer: sally pages: 6 code: p k r p f
122.230.32.236 user: luis printer: hill 3 pages: 8 code: n h n k q
printer off time: 2201

is an example of what the program will contain,

for stringprint in logfile:
        userRegex = re.search('(\suser:\s)(.+?)(\sprinter:\s)', stringprint)
        if userRegex:
            userString = userRegex.group(2)
            numpages = int(re.search('(\spages:\s)(.+?)(\scode:\s)', stringprint).group(2))

            if userString not in users:
                user[userString] = numpages
            else:
                user[userString] += numpages

my problem is the re.search isn't working properly, I believe the expression to be correct but it is clearly not. I know that \\s matches white spaces, also the .+? is the lazy version of matching the preceding token. once I find a match i use the the user.Regex.group(2) to set it to the "username". from there I then want to search for the number of pages and code (to make sure correct match) and then proceed to print it. I know that this regex is not working but I can not figure out what I am doing wrong.

when I run the program via module i get :

Traceback (most recent call last): File "C:\\Users\\brandon\\Desktop\\project3\\project3\\pages.py", line 45, in <module> log2hist("log") # version 2. File "C:\\Users\\brandon\\Desktop\\project3\\project3\\pages.py", line 29, in log2hist numpages = int(re.search('(\\spages:\\s)(.+?)(\\scode:\\s)',stringprint).group(2)) AttributeError: 'NoneType' object has no attribute 'group'

Answer 1

Description

I recommend switching up your Regex so it'll be a bit more flexible. This regex will do the following:

• capture the username
• capture the number of prints
• allow the user and pages to appear in any order. This becomes handy if you wanted to start capturing other data

The Regex

^(?=.*?user:\s+(.*?)\s)(?=.*?pages:\s+(.*?)\s).*?$

Explained

NODE                     EXPLANATION
----------------------------------------------------------------------
  ^                        the beginning of a "line"
----------------------------------------------------------------------
  (?=                      look ahead to see if there is:
----------------------------------------------------------------------
    .*?                      any character except \n (0 or more times
                             (matching the least amount possible))
----------------------------------------------------------------------
    user:                    'user:'
----------------------------------------------------------------------
    \s+                      whitespace (\n, \r, \t, \f, and " ") (1
                             or more times (matching the most amount
                             possible))
----------------------------------------------------------------------
    (                        group and capture to \1:
----------------------------------------------------------------------
      .*?                      any character except \n (0 or more
                               times (matching the least amount
                               possible))
----------------------------------------------------------------------
    )                        end of \1
----------------------------------------------------------------------
    \s                       whitespace (\n, \r, \t, \f, and " ")
----------------------------------------------------------------------
  )                        end of look-ahead
----------------------------------------------------------------------
  (?=                      look ahead to see if there is:
----------------------------------------------------------------------
    .*?                      any character except \n (0 or more times
                             (matching the least amount possible))
----------------------------------------------------------------------
    pages:                   'pages:'
----------------------------------------------------------------------
    \s+                      whitespace (\n, \r, \t, \f, and " ") (1
                             or more times (matching the most amount
                             possible))
----------------------------------------------------------------------
    (                        group and capture to \2:
----------------------------------------------------------------------
      .*?                      any character except \n (0 or more
                               times (matching the least amount
                               possible))
----------------------------------------------------------------------
    )                        end of \2
----------------------------------------------------------------------
    \s                       whitespace (\n, \r, \t, \f, and " ")
----------------------------------------------------------------------
  )                        end of look-ahead
----------------------------------------------------------------------
  .*?                      any character except \n (0 or more times
                           (matching the least amount possible))
----------------------------------------------------------------------
  $                        before an optional \n, and the end of a
                           "line"

Examples

Online Demo of Regex

http://fiddle.re/13chna

Sample Python Code

https://repl.it/CJdF/0

import re

SampleString = '''date: 2012-11-25
printer on time:  0800 
23.96.82.161 user: pei printer: core 2 pages: 2 code: r n t h p r
28.104.177.80 user: isaac printer: poster pages: 4 code: p h
printer error:  out of paper  time: 1343
180.186.109.129 user: luis printer: core 2 pages: 2 code: k n h
194.96.54.184 user: isaac printer: sally pages: 6 code: p k r p f
122.230.32.236 user: luis printer: hill 3 pages: 8 code: n h n k q
printer off time: 2201'''
print (SampleString)

## Here re.findall()
Regex=re.compile(r'^(?=.*?user:\s+(.*?)\s)(?=.*?pages:\s+(.*?)\s).*?$',re.MULTILINE)
Matches = Regex.findall( SampleString) 
Count = 0
for Match in Matches:
    # do something with each found email string
    print("[" + str(Count) + "][0] = " + Match[0])
    print("[" + str(Count) + "][1] = " + Match[1])
    print("")
    Count = Count + 1

Sample Output

[0][0] = pei
[0][1] = 2

[1][0] = isaac
[1][1] = 4

[2][0] = luis
[2][1] = 2

[3][0] = isaac
[3][1] = 6

[4][0] = luis
[4][1] = 8