How to conditionally replace numbers using vim

Question

I can see a lot of discussion on how to replace strings conditionally using :%s. But I want to do exactly this in my file that has a huge bunch of numbers in a CSV format:

1. Find numbers < -100
2. Replace them by -98

How can I do this in VIM or any other editor/script language?

Answer 1

It is possible using the submatch() function like this:

:%s/-[0-9]\+/\=submatch(0) < -100 ? -98 : submatch(0)/g

Now every number smaller than -100 will be replaced by -98 and the rest just stays the same. Note that this regex will only match negative numbers.