MATLAB: Improve Speed of Code (especially for loop)

for loopMATLABspeed

I want to analyse a log file that i created my self, basically the content is a CSV table with 5 columns {Timeindex , ActorName, X, Y, Z}. (There are only 8 Actors)
for that I made my first matlab function, in general matlab experience, ever xD which is this:
function Auswertung (matrix)
    va = size(matrix);
    bonePlotsX= zeros(8,2,100000);
    bonePlotsY= zeros(8,2,100000);
    bonePlotsZ= zeros(8,2,100000);
    %Current row in which to write for each of the roads.
    is={1,1,1,1,1,1,1,1};
    for i=1:1:(va(1))
        currentIndex=1;
        var = matrix{i,2};
        var= strtrim(var);
        switch(var)
            case "Hips"
                currentIndex=1;
            case "Spine"
                currentIndex=2;
            case "LeftUpperLeg"
                currentIndex=3;
            case "LeftLowerLeg"
                currentIndex=4;
            case "LeftFoot"
                currentIndex=5;
            case "RightUpperLeg"
                currentIndex=6;
            case "RightLowerLeg"
                currentIndex=7;
            case "RightFoot"
                currentIndex=8;
        end
        bonePlotsX(currentIndex,1,is{currentIndex})=matrix{i,1};
        bonePlotsX(currentIndex,2,is{currentIndex})=matrix{i,3};
        bonePlotsY(currentIndex,1,is{currentIndex})=matrix{i,1}; 
        bonePlotsY(currentIndex,2,is{currentIndex})=matrix{i,4};
        bonePlotsZ(currentIndex,1,is{currentIndex})=matrix{i,1};
        bonePlotsZ(currentIndex,2,is{currentIndex})=matrix{i,5};
        is{currentIndex}= is{currentIndex}+1;
    end
    %First Bone Print
    figure
    subplot(3,1,1)
    plot( bonePlotsX(1,1),bonePlotsX(1,2));
    title("X of Hips");
      subplot(3,1,1)
      plot( bonePlotsY(1,1),bonePlotsY(1,2));
      title("Y of Hips");
      subplot(3,1,1)
      plot( bonePlotsZ(1,1),bonePlotsZ(1,2));
      title("Z of Hips");
  end
The problem is it takes awfully long to complete the for loop. The sample file has just about 400 000 Lines, so not something I would consider much for a PC. How can I optimize this Loop? I tried pre allocating the bone matrices, 100 000 should be enough for even the longer logfiles.
As you see the end result should be a plot for all of the bones (in the code its just one for testing purposes)

Best Answer

You may check this example code:
[num,txt,raw] = xlsread('demo.xls') ;
name = txt ;
%%find nose
idx = strfind(name,'nose') ;
idx1 = strfind(name, 'nose');
idx1 = find(not(cellfun('isempty', idx1)));
%%nose data 
data1 = num(idx1,:) ;
Like above you can follow for other required data.
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