how do I use specific values from two different columns in a table as column headers in a matrix

hello nk19330 

please check if this accomodate your need.

if the Category 3 will be always split, i would do somehting like below.

1. create a new custom column with following code to create a column you want to use as matrix header

if [Column2]="Category 1" or [Column2]="Category 2" then [Column2] else [Column3]

2. plot the custom column into matrix visual along with all measures.

Hope this will help.

Thank you.