Let's say I have a string s
s = "?, ?, ?, test4, test5"
I know that there are three question marks, and I want to replace each question mark accordingly with the following array
replace_array = ['test1', 'test2', 'test3']
to obtain
output = "test1, test2, test3, test4, test5"
is there a function in Python, something like s.magic_replace_func(*replace_array) that will achieve the desired goal?
Thanks!
Use str.replace and replace '?' with '{}', then you can simply use the str.format method:
>>> s = "?, ?, ?, test4, test5"
>>> replace_array = ['test1', 'test2', 'test3']
>>> s.replace('?', '{}', len(replace_array)).format(*replace_array)
'test1, test2, test3, test4, test5'
Use str.replace() with a limit, and loop:
for word in replace_array:
s = s.replace('?', word, 1)
Demo:
>>> s = "?, ?, ?, test4, test5"
>>> replace_array = ['test1', 'test2', 'test3']
>>> for word in replace_array:
... s = s.replace('?', word, 1)
...
>>> s
'test1, test2, test3, test4, test5'
If your input string doesn't contain any curly braces, you could also replace the curly question marks with {} placeholders and use str.format():
s = s.replace('?', '{}').format(*replace_array)
Demo:
>>> s = "?, ?, ?, test4, test5"
>>> s.replace('?', '{}').format(*replace_array)
'test1, test2, test3, test4, test5'
If your real input text already has { and } characters, you'll need to escape those first:
s = s.replace('{', '{{').replace('}', '}}').replace('?', '{}').format(*replace_array)
Demo:
>>> s = "{?, ?, ?, test4, test5}"
>>> s.replace('{', '{{').replace('}', '}}').replace('?', '{}').format(*replace_array)
'{test1, test2, test3, test4, test5}'
And a regular expression with function approach - which scans the string only once, is more flexible in terms of adapting the replacement pattern, doesn't possibly conflict with existing formatting operations, and can be changed to provide default values if not enough replacements are available... :
import re
s = "?, ?, ?, test4, test5"
replace_array = ['test1', 'test2', 'test3']
res = re.sub('\?', lambda m, rep=iter(replace_array): next(rep), s)
#test1, test2, test3, test4, test5
to_replace = iter(replace_array) and ''.join([c if c != '?' else next(to_replace) for c in s]). Using a regular expression is more adaptable for the pattern being replaced, I have to admit.Try this:
s.replace('?', '{}').format(*replace_array)
=> 'test1, test2, test3, test4, test5'
Even better, if you substitute the ? signs with {} placeholders you can call format() directly, without calling replace() first. After that, format() takes care of everything.
