How to grab only digit values using regex

January 15, 2022

I wanted to extract only digit values from the following key value pairs data:

data='''

var char = [
    {d:new Date(1631052000000),k:67.200,o:0},
      {d:new Date(1631138400000),k:67.830,o:0},
      {d:new Date(1631224800000),k:67.420,o:0},
      {d:new Date(1631484000000),k:68.070,o:0},
      {d:new Date(1631570400000),k:67.630,o:0},
      {d:new Date(1631656800000),k:68.430,o:0},
      {d:new Date(1631743200000),k:67.500,o:0},
      {d:new Date(1631829600000),k:68.770,o:0},
      {d:new Date(1632088800000),k:68.880,o:0},];
      
      '''

Expected Output: For example

1631052000000, 67.200, 0

>Solution :

You can use \d+ to match digits. Furthermore, you can use \.\d+ in an optional group to optionally match a dot and digits following this dot.

import re

data='''

var char = [
    {d:new Date(1631052000000),k:67.200,o:0},
      {d:new Date(1631138400000),k:67.830,o:0},
      {d:new Date(1631224800000),k:67.420,o:0},
      {d:new Date(1631484000000),k:68.070,o:0},
      {d:new Date(1631570400000),k:67.630,o:0},
      {d:new Date(1631656800000),k:68.430,o:0},
      {d:new Date(1631743200000),k:67.500,o:0},
      {d:new Date(1631829600000),k:68.770,o:0},
      {d:new Date(1632088800000),k:68.880,o:0},];
      
      '''

# Construct a regex to match digits only
pattern = re.compile("\d+(?:\.\d+)?")

# Find all matches of this pattern
print(pattern.findall(data))

This outputs

['1631052000000', '67.200', '0', '1631138400000', '67.830', '0', '1631224800000', '67.420', '0', '1631484000000', '68.070', '0', '1631570400000', '67.630', '0', '1631656800000', '68.430', '0', '1631743200000', '67.500', '0', '1631829600000', '68.770', '0', '1632088800000', '68.880', '0']

You can further transform this into floats, integers, etc. depending on your need.

The entire regex used in the code is the following:

\d+         # Match 1 or more digits
(?:         # Start a non-capturing, optional group
\.          # Match a . literally
\d+         # Match 1 or more digits
)?          # Close the non-capturing, optional group