re.findall() returning empty tuples

Asked Jun 21 '19 at 09:43

Active Jun 21 '19 at 09:45

Viewed 32 times

I have a regex '[-][0-9],\s*[0-9]*(?!(km)|(Km)|(metres?)|(miles?)|(m)|(mi))'.

When I use this on regexr.com it matches '558,21' and other patterns.

but if I am using re.findall() in python

it is returning me this as the output even though '558,21' is present in text variable:

[('', '', '', '', '', ''), ('', '', '', '', '', ''), ('', '', '', '', '', ''), ('', '', '', '', '', '')]

What might be the reason for it?

edited Jun 21 '19 at 09:45

eyllanesc

asked Jun 21 '19 at 09:43

Pritam Roy

Remove all the capturing groups. You may also make sure you match at least 1 digit, use `+` with some `[0-9]`, i.e. `[0-9]*,\s*[0-9]*` => `[0-9]+(?:,\s*[0-9]+)?` – Wiktor Stribiżew Jun 21 '19 at 09:45
But then how will I implement the negative lookahead? – Pritam Roy Jun 21 '19 at 09:46
1

What is the problem with `(?!km|Km|metres?|miles?|m|mi)`? ``(?![kK]m|metres?|miles?|mi?)`` is a bit better though – Wiktor Stribiżew Jun 21 '19 at 09:47
yeah man. It solves the problem . Thanks a lot mate. – Pritam Roy Jun 21 '19 at 09:49
`r'(?i)-?[0-9]+(?:,\s*[0-9]+)?(?!\s*(?:km|metres?|miles?|mi?)\b)'` might be a better pattern, but the main point is the capturing groups always create items in the list of tuples – Wiktor Stribiżew Jun 21 '19 at 09:49

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