Categorizing range of data

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Neuromechanist 2024-1-8

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https://ww2.mathworks.cn/matlabcentral/answers/2067456-categorizing-range-of-data

评论： Dyuman Joshi 2024-1-8

Hello,

I am using vector coding to analyze coordination patterns during arm reaching, which the values are from 0 to 360. I've used an if statement to attempt to categorize each value along 1:99 normalized time points on variable phsangSE so that I can eventually get a frequency of each category in the new variable coupAng. The return in coupAng is <undefined> on all time points except the last one, which it correctly categorizes. I'm not sure where the issue is in the code, but loops aren't my strongest suit at the moment, so any help is great. Or, if there is a better way to categorize the data I'm all ears.

Thank you in advance!

coupAng = categorical(nan(1,99),1:4,["Proximal Segment Phase","In-Phase","Distal Segment Phase","Anti-Phase"]);%nan(1,99),1:4,
for i = length(phsangSE)
    if phsangSE(i) < 22.5 || phsangSE(i) >=157.5 && phsangSE(i) < 202.5 || phsangSE(i) >=337.5 && phsangSE(i) <= 360 
        coupAng(i) = ["Proximal Segment Phase"];
    elseif phsangSE(i) >= 22.5 && phsangSE(i) < 67.5 || phsangSE(i) >= 202.5 && phsangSE(i) < 247.5
            coupAng(i) = ["In-Phase"];
    elseif phsangSE(i) >= 67.5 && phsangSE(i) < 112.5 || phsangSE(i) >= 247.5 && phsangSE(i) < 292.5
            coupAng(i) = ["Distal Segment Phase"];
    elseif phsangSE(i) >=112.5 && phsangSE(i) < 157.5 || phsangSE(i) >=292.5 && phsangSE(i) < 337.5
            coupAng(i) = ["Anti-Phase"];
    end
end

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Answer 1

Dyuman Joshi 2024-1-8

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在 MATLAB Online 中打开

Because the for loop only iterates through the last element of phsangSE, thus the rest of the elements are undefined as that's how they are preallocated.

I assume that's a typo and you want to loop through all of the elements -

%As you are allocating string to each element, it is better to preallocate a string array
coupAng = strings(1, 99);
%       vv
for i = 1:length(phsangSE)
    if phsangSE(i) < 22.5 || phsangSE(i) >=157.5 && phsangSE(i) < 202.5 || phsangSE(i) >=337.5 && phsangSE(i) <= 360 
        coupAng(i) = "Proximal Segment Phase";
    elseif phsangSE(i) >= 22.5 && phsangSE(i) < 67.5 || phsangSE(i) >= 202.5 && phsangSE(i) < 247.5
            coupAng(i) = "In-Phase";
    elseif phsangSE(i) >= 67.5 && phsangSE(i) < 112.5 || phsangSE(i) >= 247.5 && phsangSE(i) < 292.5
            coupAng(i) = "Distal Segment Phase";
    elseif phsangSE(i) >=112.5 && phsangSE(i) < 157.5 || phsangSE(i) >=292.5 && phsangSE(i) < 337.5
            coupAng(i) = "Anti-Phase";
    end
end

Remove the square brackets around scalar strings, as they are superfluous.

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Neuromechanist 2024-1-8

Thanks,! I appreciate your patience. The typo without the 1: was a face palm. Your answer worked great, but my use of the || operator returned all but the first 16 cells, which were empty . I removed the || operator and created a new elseif statement with that range and now all cells are categorized.

Dyuman Joshi 2024-1-8

在 MATLAB Online 中打开

"but my use of the || operator returned all but the first 16 cells, which were empty."

That's weird. It works fine here for a linearly spaced data sample -

phsangSE = linspace(1, 360, 99);
disp(phsangSE)
  Columns 1 through 19

    1.0000    4.6633    8.3265   11.9898   15.6531   19.3163   22.9796   26.6429   30.3061   33.9694   37.6327   41.2959   44.9592   48.6224   52.2857   55.9490   59.6122   63.2755   66.9388

  Columns 20 through 38

   70.6020   74.2653   77.9286   81.5918   85.2551   88.9184   92.5816   96.2449   99.9082  103.5714  107.2347  110.8980  114.5612  118.2245  121.8878  125.5510  129.2143  132.8776  136.5408

  Columns 39 through 57

  140.2041  143.8673  147.5306  151.1939  154.8571  158.5204  162.1837  165.8469  169.5102  173.1735  176.8367  180.5000  184.1633  187.8265  191.4898  195.1531  198.8163  202.4796  206.1429

  Columns 58 through 76

  209.8061  213.4694  217.1327  220.7959  224.4592  228.1224  231.7857  235.4490  239.1122  242.7755  246.4388  250.1020  253.7653  257.4286  261.0918  264.7551  268.4184  272.0816  275.7449

  Columns 77 through 95

  279.4082  283.0714  286.7347  290.3980  294.0612  297.7245  301.3878  305.0510  308.7143  312.3776  316.0408  319.7041  323.3673  327.0306  330.6939  334.3571  338.0204  341.6837  345.3469

  Columns 96 through 99

  349.0102  352.6735  356.3367  360.0000
coupAng = strings(1, 99);
%       vv
for i = 1:length(phsangSE)
    if phsangSE(i) < 22.5 || phsangSE(i) >=157.5 && phsangSE(i) < 202.5 || phsangSE(i) >=337.5 && phsangSE(i) <= 360 
        coupAng(i) = "Proximal Segment Phase";
    elseif phsangSE(i) >= 22.5 && phsangSE(i) < 67.5 || phsangSE(i) >= 202.5 && phsangSE(i) < 247.5
            coupAng(i) = "In-Phase";
    elseif phsangSE(i) >= 67.5 && phsangSE(i) < 112.5 || phsangSE(i) >= 247.5 && phsangSE(i) < 292.5
            coupAng(i) = "Distal Segment Phase";
    elseif phsangSE(i) >=112.5 && phsangSE(i) < 157.5 || phsangSE(i) >=292.5 && phsangSE(i) < 337.5
            coupAng(i) = "Anti-Phase";
    end
end
disp(coupAng)
  Columns 1 through 9

    "Proximal Segment P…"    "Proximal Segment P…"    "Proximal Segment P…"    "Proximal Segment P…"    "Proximal Segment P…"    "Proximal Segment P…"    "In-Phase"    "In-Phase"    "In-Phase"

  Columns 10 through 21

    "In-Phase"    "In-Phase"    "In-Phase"    "In-Phase"    "In-Phase"    "In-Phase"    "In-Phase"    "In-Phase"    "In-Phase"    "In-Phase"    "Distal Segment Pha…"    "Distal Segment Pha…"

  Columns 22 through 28

    "Distal Segment Pha…"    "Distal Segment Pha…"    "Distal Segment Pha…"    "Distal Segment Pha…"    "Distal Segment Pha…"    "Distal Segment Pha…"    "Distal Segment Pha…"

  Columns 29 through 38

    "Distal Segment Pha…"    "Distal Segment Pha…"    "Distal Segment Pha…"    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"

  Columns 39 through 47

    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"    "Proximal Segment P…"    "Proximal Segment P…"    "Proximal Segment P…"    "Proximal Segment P…"

  Columns 48 through 54

    "Proximal Segment P…"    "Proximal Segment P…"    "Proximal Segment P…"    "Proximal Segment P…"    "Proximal Segment P…"    "Proximal Segment P…"    "Proximal Segment P…"

  Columns 55 through 66

    "Proximal Segment P…"    "Proximal Segment P…"    "In-Phase"    "In-Phase"    "In-Phase"    "In-Phase"    "In-Phase"    "In-Phase"    "In-Phase"    "In-Phase"    "In-Phase"    "In-Phase"

  Columns 67 through 74

    "In-Phase"    "In-Phase"    "Distal Segment Pha…"    "Distal Segment Pha…"    "Distal Segment Pha…"    "Distal Segment Pha…"    "Distal Segment Pha…"    "Distal Segment Pha…"

  Columns 75 through 83

    "Distal Segment Pha…"    "Distal Segment Pha…"    "Distal Segment Pha…"    "Distal Segment Pha…"    "Distal Segment Pha…"    "Distal Segment Pha…"    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"

  Columns 84 through 94

    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"    "Anti-Phase"    "Proximal Segment P…"    "Proximal Segment P…"

  Columns 95 through 99

    "Proximal Segment P…"    "Proximal Segment P…"    "Proximal Segment P…"    "Proximal Segment P…"    "Proximal Segment P…"