CODEWITHSUNDEEP
pythonpython-3.xregex
kynnemall
kynnemall

Reputation: 888

Python regex get pairs of floats from string if present

I have some strings which contain a pairs of frequencies or pairs of frequency ranges

My regex function gets the following list from that example string:

example_string = ':2.400-2.483ghz;5.725-5.850ghz

transmissionpower(eirp),2'
re.findall(r"(\d+\.\d+.hz)", example_string)
# example output: ['2.483ghz', '5.850ghz']

How can I extract the range of frequencies rather than just the single float after the - character?

Output should be ['2.400-2.483ghz', '5.725-5.850ghz']

Upvotes: 0

Views: 62

Answers (2)

Brent Writes Code
Brent Writes Code

Reputation: 19603

Something like this should (mostly) work to find all the occurences of those strings in the code (it should handle any number of ranges in the line):

>>> example_string = ':2.400-2.483ghz;5.725-5.850ghz

transmissionpower(eirp),2'
>>> re.findall('([0-9.]+-[0-9.]+.?hz)', example_string)
['2.400-2.483ghz', '5.725-5.850ghz']

To break it down:

  • [0-9.]+ - will find 1 or more numbers and .s together (e.g. 2.400)
  • .?hz finds 0 or 1 characters followed by 'hz' so it should handle most units (e.g. hz, ghz, etc.)

The whole thing essentially looks for <number><dash><number><units> zero or more times per line.

It's worth pointing out that, like most regexes, this is still pretty brittle so if the string is malformatted, if it's GHz instead of ghz, if the numbers are in scientific notation, etc., it will break, but hopefully you can adjust as needed.

Upvotes: 3

anubhava
anubhava

Reputation: 785128

You may use this regex:

(?:\d+\.\d+-)?\d+\.\d+.hz

RegEx Demo

Code:

>>> import re
>>> s = ':2.400-2.483ghz;5.725-5.850ghz&#x0d;&#x0d;transmissionpower(eirp),2'
>>> re.findall(r'(?:\d+\.\d+-)?\d+\.\d+.hz', s);
['2.400-2.483ghz', '5.725-5.850ghz']

Explanation:

  • (?:\d+\.\d+-)?: In an optional group match a floating point number followed by hyphen
  • \d+\.\d+: Match a floating point number
  • .hz: Match any character followed by hz

Upvotes: 2

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