在Python中查找并替换字符串

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?

Answer 1

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'

Answer 2

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'

Answer 3

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.

Answer 4

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