Find and replace a string in Python

Question

I have a string like this:

 line = "Student   =  Small   |1-2|   Student"

I want to replace this line to

 line = "StudentShort  =  Small  |1-2|    StudentShort"

The problem is I don't know wheither first and last words are Student or anything else in string. I mean it can be Men, Women, Teacher anything.

I only know that if there is small in string I have to replace first and last word with that name and short

Can some one help?

Ryan Saxe · Accepted Answer · 2013-05-07 14:33:02Z

2

You want to add "Short" to the first and last word of the string...My advice would be to split and then use indexing and then join!

In [202]: line = "Teacher   =  Small   |1-2|   Student"

In [203]: line = line.split()

In [204]: line[0] += "Short"

In [205]: line[-1] += "Short"

In [206]: line = "  ".join(line)

In [207]: line
Out[207]: 'TeacherShort  =  Small  |1-2|  StudentShort'

I think it would be useful to have this in a function:

def customize_string(string,add_on):
    if "small" in string:
        line = string.split()
        line[0] += add_on
        line[-1] += add_on
        return "  ".join(line)
    else:
        return string

here is using it to show that it works!

In [219]: customize_string(line,"Short")
Out[219]: 'TeacherShort  =  Small  |1-2|  StudentShort'

edited May 7, 2013 at 14:33

answered May 7, 2013 at 14:04

Ryan Saxe

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6 Comments

hulk007 Over a year ago

The problem is I don't know what are my first and last word in string

Ryan Saxe Over a year ago

Your question is unclear then and this satisfies your example...so what you're saying is that you want to be able to replace an instance without knowing what it is first?

hulk007 Over a year ago

Yes, The problem is I don't know what my first and last word is in the string, it can be teacher, or men or women anything

Ryan Saxe Over a year ago

OH, so your question isn't all cases in student, it is for the first and last word? And is the string formatted where everything is separated by 2 spaces?

Ashwini Chaudhary Over a year ago

str.split won't preserve the irregular spaces in the string.

|

prashantsunkari · Accepted Answer · 2013-05-07 14:06:54Z

1

You can use the String replace method in python..

http://docs.python.org/2/library/string.html#string.replace

    string.replace(s, old, new[, maxreplace])
    Return a copy of string s with all occurrences of substring
    old replaced by new. If the optional argument maxreplace is 
    given, the first maxreplace occurrences are replaced.

answered May 7, 2013 at 14:06

prashantsunkari

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2 Comments

hulk007 Over a year ago

The problem is I don't know what are my first and last word in string

prashantsunkari Over a year ago

You can find it by splitting the string and getting the first and last word p.split()[0] (give first) splitListCount=len(line.split()); last=line.split()[splitListCount-1];

Ashwini Chaudhary · Accepted Answer · 2013-05-07 14:46:06Z

1

Something like this using regex:

>>> line = "Student   =  Small   |1-2|   Student"
>>> if re.search(r"\bSmall\b",line):
    print re.sub("^(\w+)|(\w+)$",lambda x:x.group()+"Short",line)
'StudentShort   =  Small   |1-2|   StudentShort'

>>> line = "Men   =  Small   |1-2|   Men"
>>> if re.search(r"\bSmall\b",line):
    print re.sub("^(\w+)|(\w+)$",lambda x:x.group()+"Short",line)
'MenShort   =  Small   |1-2|   MenShort'

An improved version of above code(as suggested by @thg435):

def solve(strs, match, word):
    if re.search(r"\b{0}\b".format(match), strs):
         return re.sub(r"(^\w+|\w+$)","\g<0>{0}".format(word), strs)

>>> solve("Men   =  Small   |1-2|   Men", "Small", "Short")
'MenShort   =  Small   |1-2|   MenShort'
>>> solve("Student   =  Small   |1-2|   Student", "Small", "Short")
'StudentShort   =  Small   |1-2|   StudentShort'

edited May 7, 2013 at 14:46

answered May 7, 2013 at 14:04

Ashwini Chaudhary

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6 Comments

hulk007 Over a year ago

The problem is I don't know what are my first and last word in string

georg Over a year ago

Just \1Short instead of lambda.

Ashwini Chaudhary Over a year ago

@thg435 I tried that before using lambda but it returned '\x01Short and with raw string it raised error.

georg Over a year ago

@AshwiniChaudhary: interesting. You might want to change the expr to (^\w+|\w+$) or use \g<0> in replacement to denote the group 0.

Ryan Saxe Over a year ago

you forgot to answer the whole question! He only needs to add "Short" if the string contains "small"

|

Enfenion · Accepted Answer · 2013-05-07 14:09:24Z

0

This selects the "Student" part based on the equals-sign by splitting the string. then it replaces it using line.replace.

line = "Student   =  Small   |1-2|   Student"
name = line.split('=',1)[0].strip()
line = line.replace(name,name+'Short')
print line

answered May 7, 2013 at 14:09

Enfenion

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