import re
regex = re.compile(r"""
(?<=[ \t])-?
(?:
(?:
\d
|[1-9]\d+
|[1-9]\d*\.\d{1,3}(?<!0)
|\.\d{1,3}(?<!0)
)|(?:
(\.0*)0
|(0+)\.\d{0,2}[1-9]
|(0+)(?:0|[1-9]\d*)\.?\d*
|\d+(\.0*)
|\d*\.(?:[1-9]|\d[1-9])?(0+)
|\d*\.\d{3}(\d+)
)
)
(?=[ \t]|$)[ \t]?
""", flags=re.VERBOSE | re.MULTILINE)
test_str = ("Valid:\n"
"* Integers\n"
" 0 1 10 123\n"
" -0 -1 -10 -123\n"
"* Floats <1, without leading zero, (1<=precision<=3)\n"
" .1 .01 .001 .12 .123\n"
" -.1 -.01 -.001 -.12 -.123\n"
"* Floats >1, (1<=precision<=3)\n"
" 1.1 1.01 1.001 1.12 1.123 12.1 12.12 12.123 123.1 123.12 123.123\n"
" -1.1 -1.01 -1.001 -1.12 -1.123 -12.1 -12.12 -12.123 -123.1 -123.12 -123.123\n\n"
"Invalid (in order of capture):\n"
"* [1] Zero as float with only trailing zeros\n"
" .0 .00 .000\n"
" -.0 -.00 -.000\n"
"* [2] Floats <1, with leading zero\n"
" 0.1 0.01 0.001 0.12 0.123\n"
" -0.1 -0.01 -0.001 -0.12 -0.123\n"
"* [3] Integers with leading zeros\n"
" 00 01 012 0123 000 001 0012 00123 0000 0001 00012 000123\n"
" -00 -01 -012 -0123 -000 -001 -0012 -00123 -0000 -0001 -00012 -000123\n"
"* [4] Integers as float ('fake floats')\n"
" 0. 1. 12. 123.\n"
" 0.0 0.00 0.000 0.0000\n"
" 1.0 1.00 1.000\n"
" -0. -1. -12. -123.\n"
" -0.0 -0.00 -0.000 -0.0000\n"
" -1.0 -1.00 -1.000\n"
"* [5] Floats with trailing zeros\n"
" 1.10 1.100 1.120 .10 .100 .120\n"
" -1.10 -1.100 -1.120 -.10 -.100 -.120\n"
"* [6] Any float with precision >3\n"
" 0.0001 0.0012 0.0123 0.1234\n"
" 1.0001 1.0012 1.0123 1.1234\n"
" 10.0001 10.0012 10.0123 10.1234\n"
" 100.0001 100.0012 100.0123 100.1234\n"
" -0.0001 -0.0012 -0.0123 -0.1234\n"
" -1.0001 -1.0012 -1.0123 -1.1234\n"
" -10.0001 -10.0012 -10.0123 -10.1234\n"
" -100.0001 -100.0012 -100.0123 -100.1234\n")
matches = regex.finditer(test_str)
for match_num, match in enumerate(matches, start=1):
print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}")
for group_num, group in enumerate(match.groups(), start=1):
print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Python, please visit: https://docs.python.org/3/library/re.html