Generalizing the Access to an Array of Structures in MATLAB

(Originally posted on Doug's MATLAB Video Tutorials blog.)

Recently a MATLAB user asked me how to make it possible to work with an array of structures in such a way that she could filter the array of structures and then combine the remaining fields. Once combined she would run arbitrary processing functions on this combined data.

This generalized architecture allows her to not use switch case and other flow control. The strings that represent the fields of interest could come from a GUI making her GUI able to process in many arbitrary and customizable ways.

Here is the code from the post:

clear
clc

s(1).condition = 1;
s(2).condition = 1;
s(3).condition = 2;
s(4).condition = 2;

s(1).velocity = [11:21];
s(2).velocity = [22:32];
s(3).velocity = [33:43];
s(4).velocity = [44:54];

s(1).acceleration = [111:121];
s(2).acceleration = [122:132];
s(3).acceleration = [133:143];
s(4).acceleration = [144:154];

fieldToFilterBy    = 'condition';
valueToFilterBy    = 2;
fieldToProcess     = 'acceleration';
processingFunction = @mean;


listOfFilterValues    = [s.(fieldToFilterBy)];
vi                    = (listOfFilterValues == valueToFilterBy)
filteredStructure     = s(vi)
mergedFieldOfInterest = [filteredStructure(:).(fieldToProcess)]
processedFilteredData = feval(processingFunction, mergedFieldOfInterest)