topic Re: How to compare two strings and find the difference in Splunk Search

How to compare two strings and find the difference

edoardo_vicendo — Mon, 04 Nov 2019 17:56:50 GMT

Hi all,

In the middle of a search, I have two string fields, one is called A and the other B (both have the ";" as delimiter but the number of values inside is variable):

A=test;sample;example
B=test;sample;example;check

I would like to compare the two string and have the difference as result in a new field called C (so suppose C=check).
Is there any way to achieve that (like doing an Excel VLOOKUP without performing a sub-search that can affect the search performance)?

Thanks a lot,
Edoardo

Re: How to compare two strings and find the difference

MuS — Mon, 04 Nov 2019 19:29:27 GMT

Hi edoardo_vicendone,

try something like this:

| makeresults 
| eval A="test;sample;example", 
    B="test;sample;example;check" 
| makemv delim=";" A 
| makemv delim=";" B 
| mvexpand A 
| mvexpand B 
| stats values(A) AS A by B `comment(" Everything up til here creates events, please ignore ...")`
| eval C=if(B!=A, B, null())

The first 8 lines create, prepare the dummy events and the last line does the actual comparison of field A and B and puts the result into the new field C.

The important part of the SPL is line 4-7 where I create the multi value fields and split them so we are able to compare the values.

Hope this helps ...

cheers, MuS

Re: How to compare two strings and find the difference

woodcock — Tue, 05 Nov 2019 05:23:02 GMT

This comes up quite a bit. First you must make A and B multi-valued like this:

...| makemv delim=";" A | makemv delim=";" B ...

Then do something like one of these, depending on exactly what you need:
https://answers.splunk.com/answers/407106/comparing-multivalue-fields-by-percentage.html
https://answers.splunk.com/answers/567851/how-can-i-compare-mvfields-and-get-a-diff.html
https://answers.splunk.com/answers/740480/how-to-compare-characters-in-two-fields-and-return.html
https://answers.splunk.com/answers/762432/multivalue-differences.html
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Re: How to compare two strings and find the difference

edoardo_vicendo — Tue, 05 Nov 2019 14:59:22 GMT

@woodcock
Thanks a lot I have followed one of your previous solutions (see https://answers.splunk.com/answers/567851/how-can-i-compare-mvfields-and-get-a-diff.html) and it worked fine

Re: How to compare two strings and find the difference

edoardo_vicendo — Tue, 05 Nov 2019 15:00:26 GMT

@MuS
Thanks a lot for your feedback!