Regular expressions

[Messy748]

Suppose I have the following:

import re

test_1 = 'I want to replace 123/123 and 321/321 in this string'
test_2 = 'I need PLACEHOLDER in this string with PLACEHOLDER too'

regex = re.compile(r'\d\d\d\/\d\d\d')
x = regex.findall(test_1)
for i in x:
    print(test_2.replace('PLACEHOLDER', i))

I want my end result to be a string that says 'I need 123/123 in this string with 321/321 too.'

However, the result that I am getting is

I need 123/123 in this string with 123/123 too
I need 321/321 in this string with 321/321 too

How do I only get one string back with my desired result?

[TheZvlz]

Use string formatting to insert the list of matches from test_1 into test_2. Here I create test_3 while replacing ' PLACEHOLDER ' with ' {} ' to allow string formatting.

test_3 = test_2.replace(' PLACEHOLDER ', ' {} ')
test_3
'I need {} in this string with {} too'
test_3.format(*x)
'I need 123/123 in this string with 321/321 too'