Regex match only if multiple patterns found (python)

Question

I'm trying to extract data from sentences such as:

"monthly payment of 525 and 5000 drive off"

using a python regex search function: re.search()

My regex query string is as follows for down payment:

match1 = "(?P<down_payment>\d+)\s*(|\$|dollars*|money)*\s*" + \
         "(down|drive(\s|-)*off|due\s*at\s*signing|drive\s*-*\s*off)*"

My problem is that it matches the wrong numerical value as down payment, it gets both 525, and 5000.

How can I improve my regex string such that it only matches an element if another element is successfully matched as well?

In this case, for example, both 5000 and drive-off matched so we can extract 5000 as down_payment, but 525 did not match with the any down payment values, so it should not even consider the 525.

Clearer explanation here

Remove the final asterisk to make the right-hand side context obligatory. Check regex101.com/r/bm8EHE/1. What was the point of making it optional? — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Jan 4, 2017 at 7:25
Please clarify the requirements or let know if my suggestion works for you. — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Jan 4, 2017 at 7:34
@WiktorStribiżew very new at regex and I misunderstood how it works. I thought it grabs parts of patterns too... that extra asterix was a typo I should use a + or remove it instead. thank you — NutellaAddict
– NutellaAddict, Commented Jan 4, 2017 at 7:37
So, the first numbered capturing group ((|\$|dollars*|money)*) can be still missing, right? And the last one is obligatory. — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Jan 4, 2017 at 7:38

Wiktor Stribiżew · Accepted Answer · 2017-01-04 07:40:15Z

2

I suggest removing the final * quantifier to match exactly one occurrence of the pattern:

(?P<down_payment>\d+)\s*(?:\$|dollars*|money)?\s*(down|drive[\s-]*off|due\s*at\s*signing|drive\s*-*\s*off)

See the regex demo

answered Jan 4, 2017 at 7:40

Wiktor Stribiżew

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