As a workaround to align floats to decimal separator for tabular numeric data, I tried to find a regex to replace (globally a posteriori) trailing zeros with spaces, with the following rules:
Due also to Python regex engine limitation on look-behind requiring fixed-width pattern, I wasn't able to find a satisfactory solution. Here is a working example of my tries (Python 3.x); do not rely on vertical bars in your solution, they are in the example just for clarity purpose:
import re
# formatmany is just a way to speed up building of multiline string of tabular data
formatmany=lambda f:lambda *s:'\n'.join(f.format(*x) for x in s)
my_list = [[12345, 12.345, 12.345, 12.345],
[12340, 12.34 , 12.34 , 12.34 ],
[12345, 12.005, 12.005, 12.005],
[12340, 12.04 , 12.04 , 12.04 ],
[12300, 12.3 , 12.3 , 12.3 ],
[12000, 12.0 , 12.0 , 12 ]]
my_format = formatmany('|{:8d}|{:8.2f}|{:8.3f}|{:8.4f}|')
my_string = my_format(*my_list) # this is the formatted multiline string with trailing zeros
print('\nOriginal string:\n')
print(my_string)
print('\nTry 1:\n')
print(re.sub(r'(?<!\.)0+(?=[^0-9\.]|$)',lambda m:' '*len(m.group()),my_string))
print('\nTry 2:\n')
print(re.sub(r'(\d)0+(?=[^\d]|$)',r'\1',my_string))
which prints
Original string:
| 12345| 12.35| 12.345| 12.3450|
| 12340| 12.34| 12.340| 12.3400|
| 12345| 12.01| 12.005| 12.0050|
| 12340| 12.04| 12.040| 12.0400|
| 12300| 12.30| 12.300| 12.3000|
| 12000| 12.00| 12.000| 12.0000|
Try 1:
| 12345| 12.35| 12.345| 12.345 |
| 1234 | 12.34| 12.34 | 12.34 |
| 12345| 12.01| 12.005| 12.005 |
| 1234 | 12.04| 12.04 | 12.04 |
| 123 | 12.3 | 12.3 | 12.3 |
| 12 | 12.0 | 12.0 | 12.0 |
Try 2:
| 12345| 12.35| 12.345| 12.345|
| 1234| 12.34| 12.34| 12.34|
| 12345| 12.01| 12.005| 12.005|
| 1234| 12.04| 12.04| 12.04|
| 123| 12.3| 12.3| 12.3|
| 12| 12.0| 12.0| 12.0|
Try 1 replace trailing zeros also in integers, try 2 was taken from another solution for replacing trailing zeros in a single float. Both are unsatisfactory, since the desired output should be:
| 12345| 12.35| 12.345| 12.345 |
| 12340| 12.34| 12.34 | 12.34 |
| 12345| 12.01| 12.005| 12.005 |
| 12340| 12.04| 12.04 | 12.04 |
| 12300| 12.3 | 12.3 | 12.3 |
| 12000| 12.0 | 12.0 | 12.0 |
Why this is not a duplicate question
stribizhev's (previous but not completely satisfactory) answer gave me the idea to get to a general solution:
re.sub(r'(?<=\.)(\d+?)(0+)(?=[^\d]|$)',lambda m:m.group(1)+' '*len(m.group(2))