This example (taken from Tutorial 37 in the original Max tutorials) demonstrates one way the passpct program, from the example "Pass a certain percentage of bangs", could be used. In order for this patch to work properly, you'll need to download that patch, passpct.maxpat, and store it in the Max file search path.
jit.matrixset has write and read messages that allow you to store and recall its contents in a file, just as you would do with most presets.
[In order for this example to work properly, you should first download the file called noiseburstpresets.json and save it with that name somewhere in the Max file search path.]
[In order for this example to work properly, you should first download the file called twocloudspresets.json and save it with that name somewhere in the Max file search path.]