Negative Lookbehind (Decimals Without $) in PY
Use negative lookbehind `(?<!...)` to match decimal numbers NOT preceded by a dollar sign.
Try it in the PY tester →Pattern
regexPY
(?<!\$)\b\d+\.\d{2}\b (flags: g)Python (re) code
pyPython
import re
pattern = re.compile(r"(?<!\$)\b\d+\.\d{2}\b")
input_text = "Price $19.99 vs ratio 1.50"
for m in pattern.finditer(input_text):
print(m.group(0))Stdlib `re` module — no third-party dependency. Works on Python 3.6+.
How the pattern works
(?<!\$) is a zero-width assertion that succeeds only when the position is NOT preceded by `$`. \b\d+\.\d{2}\b then matches a decimal with exactly two fractional digits. JS and Python both support negative lookbehind; Go's RE2 does NOT support any lookbehind at all.
Examples
Input
Price $19.99 vs ratio 1.50Matches
1.50
Input
Discount 10.00 off $99.99Matches
10.00
Input
$5.00 onlyNo match
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