Posts Tagged ‘Numbers’

HowTo: Extract numeric suffix from a string in Python

I recently needed to extract a numeric suffix from a string value in Python. Initially I did the following:

import re

def extractNumSuffix(value):

    return (None if (‘^\D*(\d+)$’, value, re.IGNORECASE)) is None else

Note that return has a single-line expression.



prints 1030

Tried it online at:


However, then I found out that Assignment Expressions in Python only work from Python 3.8 and up, so I changed it to this one:

import re

def extractNumSuffix(value):"^\D*(\d+)$", value, re.IGNORECASE)
    return (None if search is None else

which should work in Python 2.x too. Don’t forget to import the regular expressions (re) module.

HowTo: round a number up to N decimal digits in Javascript

Was just trying to round-off some Google Maps coordinates for display in Javascript up to 3 decimal digits and that was a bit like a blast from the past (the end of the ‘90s to be more accurate)…

So here’s my contributed answer at:

This works for rounding to N digits (if you just want to truncate to N digits remove the Math.round call and use the Math.trunc one):

function roundN(value, digits) {
   var tenToN = 10 ** digits;
   return /*Math.trunc*/(Math.round(value * tenToN)) / tenToN;

Had to resort to such logic at Java in the past when I was authoring data manipulation E-Slate components. That is since I had found out that adding 0.1 many times to 0 you’d end up with some unexpectedly long decimal part (this is due to floating point arithmetics).

A user comment at Format number to always show 2 decimal places calls this technique scaling.

Some mention there are cases that don’t round as expected and at this is suggested instead:

function round(value, decimals) {
  return Number(Math.round(value+'e'+decimals)+'e-'+decimals);


Prime links


btw, via the last link I came across to the very interesting “On-Line Encyclopedia of Integer Sequences” (a service of Their search facility allows you to enter a series of numbers separated by space or comma and check if they exist in some known integer number series.

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