From Vim Tips Wiki
created 2002 · complexity intermediate · author Stanislav Sitar · version 6.0
Here is how to calculate the sum of all numbers matching some pattern, for example, the first number on each line with a number, or the numbers following a
$ ($10+$20). This version only handles unsigned integers.
 Sum function
First, define the following function.
let g:S = 0 "result in global variable S function! Sum(number) let g:S = g:S + a:number return a:number endfunction
In Vim, you could copy the above lines then type
:@" to execute the copied lines (to define the function). Or, you could put the code in a file in your plugin directory, or in your vimrc.
The function adds the given number onto the sum in the global variable
S. The function returns the given number so that it can be used in a substitute command without changing the number.
Suppose you have this text:
Here are some items: Take 10 apples and 20 pears then 30 walnuts.
You can add the numbers with these commands:
:let g:S=0 :%s/\d\+/\=Sum(submatch(0))/ :echo g:S
The first line clears the variable used to hold the sum. The third line displays the sum.
The substitute replaces the first occurrence of
\d\+ (one or more digits) on each line. The replacement
\= is the result of the expression
Sum(submatch(0)) which calls the
Sum() function. The
submatch(0) is the text matched by the search pattern (the number which was found).
Using the following would include all numbers in each line:
This adds only the numbers following a
$ character (the
\zs starts the search hit after the
$ is found):
This adds only the last number on each line that contains a number:
If you want to replace the numbers in the file with a running total, in the
Sum() function, replace:
Float numbers could be handled easily: