用到目前为止已出现的次数替换每次出现的字符串

Question

I have a string with placeholders and I want to attach an index to wach of the placeholders.

eg

'This @placeholder is @placeholder'

Should become

'This @param0 is @param1'

Assuming I have a list of params with 2 values(matches the number of time @placeholder occurs) .

One optional solution would be.

result = ''
parts = my_text.split('@placeholder')
for i in range(0, len(params)):
  result += '{}@param{}'.format(parts[i], i)
return result

Another option is to keep replacing the placeholder with the current index, but this means scanning the string len(params) times.

for i in range(0, len(params)):
  my_text = my_text.replace('@placeholder', '@param{}'.format(i), 1)

is there a better solution for doing this in python?

Answer 1

How about a simple re.sub solution with a callback and counter?

>>> import itertools
>>> c = itertools.count()
>>> text = 'This @placeholder is @placeholder'
>>> re.sub(r'\b@placeholder\b', lambda x: f'@param{next(c)}', text)
'This @param0 is @param1'

Answer 2

Using the answer by @Ajax1234 I can just replace the place holder with {} and use formatting with an array.

my_text = 'This param{} is param{}'
print(my_text.format(i for i in range(len(params))]))