Develop Reference

Regex to get all occurrences of a pattern followed by a value in a comma separate string

This is in python
Input string:
Str = 'Y=DAT,X=ZANG,FU=_COG-GAB-CANE-,FU=FARE,T=TART,RO=TOP,FU=#-_MAP.com-,Z=TRY'
Expected output
'FU=_COG-GAB-CANE_,FU=FARE,FU=#-_MAP.com_'
here 'FU=' is the occurence we are looking for and the value which follows FU=
return all occurrences of FU=(with the associated value for FU=) in a comma-separated string, they can occur anywhere within the string and special characters are allowed.

Here is one approach.
>>> import re
>>> str_ = 'Y=DAT,X=ZANG,FU=FAT,T=TART,FU=GEM,RO=TOP,FU=MAP,Z=TRY'
>>> re.findall.__doc__[:58]
'Return a list of all non-overlapping matches in the string'
>>> re.findall(r'FU=\w+', str_)
['FU=FAT', 'FU=GEM', 'FU=MAP']
>>> ','.join(re.findall(r'FU=\w+', str_))
'FU=FAT,FU=GEM,FU=MAP'

Got it working
Python Code
import re
str_ = 'Y=DAT,X=ZANG,FU=_COG-GAB-CANE-,FU=FARE,T=TART,RO=TOP,FU=#-_MAP.com-,Z=TRY'
str2='FU='+',FU='.join(re.findall(r'FU=(.*?),', str_))
print(str2)
Gives the desired output:
'FU=_COG-GAB-CANE-,FU=FARE,FU=#-_MAP.com-'
Successfully gives me all the occurrences of FU= followed by values, irrespective of order and number of special characters.
Although a bit unclean way as I am manually adding FU= for the first occurrence.
Please suggest if there is a cleaner way of doing it ? , but yes it gets the work done.

Replacing when a word is in another word but with special circumstances

My program replaces tokens with values when they are in a file. When reading in a certain line it gets stuck here is an example:
1.1.1.1.1.1.1.1.1.1 Token100.1 1.1.1.1.1.1.1Token100a
The two tokens in the example are Token100 and Token100a. I need a way to only replace Token100 with its data and not replace Token100a with Token100's data with an a afterwards. I can't look for spaces before and after because sometimes they are in the middle of lines. Any thoughts are appreciated. Thanks.

You can use regex:
import re
line = "1.1.1.1.1.1.1.1.1.1 Token100.1 1.1.1.1.1.1.1Token100a"
match = re.sub("Token100a", "data", line)
print(match)
Outputs:
1.1.1.1.1.1.1.1.1.1 Token100.1 1.1.1.1.1.1.1data
More about regex here:
https://www.w3schools.com/python/python_regex.asp

You can use a regular expression with a negative lookahead to ensure that the following character is not an "a":
>>> import re
>>> test = '1.1.1.1.1.1.1.1.1.1 Token100.1 1.1.1.1.1.1.1Token100a'
>>> re.sub(r'Token100(?!a)', 'data', test)
'1.1.1.1.1.1.1.1.1.1 data.1 1.1.1.1.1.1.1Token100a'

How to parse values appear after the same string in python?

I have a input text like this (actual text file contains tons of garbage characters surrounding these 2 string too.)
(random_garbage_char_here)**value=xxx**;(random_garbage_char_here)**value=yyy**;(random_garbage_char_here)
I am trying to parse the text to store something like this:
value1="xxx" and value2="yyy".
I wrote python code as follows:
value1_start = content.find('value')
value1_end = content.find(';', value1_start)
value2_start = content.find('value')
value2_end = content.find(';', value2_start)
print "%s" %(content[value1_start:value1_end])
print "%s" %(content[value2_start:value2_end])
But it always returns:
value=xxx
value=xxx
Could anyone tell me how can I parse the text so that the output is:
value=xxx
value=yyy

Use a regex approach:
re.findall(r'\bvalue=[^;]*', s)
Or - if value can be any 1+ word (letter/digit/underscore) chars:
re.findall(r'\b\w+=[^;]*', s)
See the regex demo
Details:
\b - word boundary
value= - a literal char sequence value=
[^;]* - zero or more chars other than ;.
See the Python demo:
import re
rx = re.compile(r"\bvalue=[^;]*")
s = "$%$%&^(&value=xxx;$%^$%^$&^%^*value=yyy;%$#^%"
res = rx.findall(s)
print(res)

Use regex to filter the data you want from the "junk characters":
>>> import re
>>> _input = '#4#5%value=xxx38u952035983049;3^&^*(^%$3value=yyy#%$#^&*^%;$#%$#^'
>>> matches = re.findall(r'[a-zA-Z0-9]+=[a-zA-Z0-9]+', _input)
>>> matches
['value=xxx', 'value=yyy']
>>> for match in matches:
print(match)
value=xxx
value=yyy
>>>
Summary or the regular expression:
[a-zA-Z0-9]+: One or more alphanumeric characters
=: literal equal sign
[a-zA-Z0-9]+: One or more alphanumeric characters

For this input:
content = '(random_garbage_char_here)**value=xxx**;(random_garbage_char_here)**value=yyy**;(random_garbage_char_here)'
use a simple regex and manually strip off the first and last two characters:
import re
values = [x[2:-2] for x in re.findall(r'\*\*value=.*?\*\*', content)]
for value in values:
print(value)
Output:
value=xxx
value=yyy
Here the assumption is that there are always two leading and two trailing * as in **value=xxx**.

You already have good answers based on the re module. That would certainly be the simplest way.
If for any reason (perfs?) you prefere to use str methods, it is indeed possible. But you must search the second string past the end of the first one :
value2_start = content.find('value', value1_end)
value2_end = content.find(';', value2_start)

Using parentheses as delimiter in re or str.split() python

I am trying to split a string such as: add(ten)sub(one) into add(ten) sub(one).
I can't figure out how to match the close parentheses. I have used re.sub(r'\\)', '\\) ') and every variation of escaping the parentheses,I can think of. It is hard to tell in this font but I am trying to add a space between these commands so I can split it into a list later.

There's no need to escape ) in the replacement string, ) has a special a special meaning only in the regex pattern so it needs to be escaped there in order to match it in the string, but in normal string it can be used as is.
>>> strs = "add(ten)sub(one)"
>>> re.sub(r'\)(?=\S)',r') ', strs)
'add(ten) sub(one)'
As #StevenRumbalski pointed out in comments the above operation can be simply done using str.replace and str.rstrip:
>>> strs.replace(')',') ').strip()
'add(ten) sub(one)'

d = ')'
my_str = 'add(ten)sub(one)'
result = [t+d for t in my_str.split(d) if len(t) > 0]
result = ['add(ten)','sub(one)']

Create a list of all substrings
import re
a = 'add(ten)sub(one)'
print [ b for b in re.findall('(.+?\(.+?\))', a) ]
Output:
['add(ten)', 'sub(one)']

python: how to remove '$'?

All I want to do is remove the dollar sign '$'. This seems simple, but I really don't know why my code isn't working.
import re
input = '$5'
if '$' in input:
input = re.sub(re.compile('$'), '', input)
print input
Input still is '$5' instead of just '5'! Can anyone help?

Try using replace instead:
input = input.replace('$', '')
As Madbreaks has stated, $ means match the end of the line in a regular expression.
Here is a handy link to regular expressions: http://docs.python.org/2/library/re.html

In this case, I'd use str.translate
>>> '$$foo$$'.translate(None,'$')
'foo'
And for benchmarking purposes:
>>> def repl(s):
... return s.replace('$','')
...
>>> def trans(s):
... return s.translate(None,'$')
...
>>> import timeit
>>> s = '$$foo bar baz $ qux'
>>> print timeit.timeit('repl(s)','from __main__ import repl,s')
0.969965934753
>>> print timeit.timeit('trans(s)','from __main__ import trans,s')
0.796354055405
There are a number of differences between str.replace and str.translate. The most notable is that str.translate is useful for switching 1 character with another whereas str.replace replaces 1 substring with another. So, for problems like, I want to delete all characters a,b,c, or I want to change a to d, I suggest str.translate. Conversely, problems like "I want to replace the substring abc with def" are well suited for str.replace.
Note that your example doesn't work because $ has special meaning in regex (it matches at the end of a string). To get it to work with regex you need to escape the $:
>>> re.sub('\$','',s)
'foo bar baz qux'
works OK.

$ is a special character in regular expressions that translates to 'end of the string'
you need to escape it if you want to use it literally
try this:
import re
input = "$5"
if "$" in input:
input = re.sub(re.compile('\$'), '', input)
print input

You need to escape the dollar sign - otherwise python thinks it is an anchor http://docs.python.org/2/library/re.html
import re
fred = "$hdkhsd%$"
print re.sub ("\$","!", fred)
>> !hdkhsd%!

Aside from the other answers, you can also use strip():
input = input.strip('$')