Building a matrix inside a for loop

Hi guys, can anyone help me with this please. Thanks.

So i have this Excel file. I filtered a column and then did some operations on the filtered data .

in the end, I wanna create a new matix, A, with the following characteristics. The matrix should have dimension: partID rows* 5 columns. First colum should contain the partID number (from 3 to 15), second column should contain the value of M associated with the partID, third column S, fourth m and fifth s.

how do i build A inside the cycle?

[Turlough Hughes]

Can you share the file?

[Murstoe]

thanks you, Here is the file excel.

[Turlough Hughes]

Murstoe, it's bad form to remove your question after being given an answer. Can you put it back?

[Stephen23]

Original question from Google Cache:

"Building a matrix inside a for loop"

Hi guys, can anyone help me with this please. Thanks.

So i have this Excel file. I filtered a column and then did some operations on the filtered data .

in the end, I wanna create a new matix, A, with the following characteristics. The matrix should have dimension: partID rows* 5 columns. First colum should contain the partID number (from 3 to 15), second column should contain the value of M associated with the partID, third column S, fourth m and fifth s.

how do i build A inside the cycle?

xlsData = xlsread('PartS_all.csv');
partID=xlsData(:,4);
for partID=3:15
   
   
    tenpm=xlsData(xlsData(:,4)==partID,:);
    part=sortrows(tenpm, 2);         %Sort second column
    
    M(partID)=mean(part(:,8));
    S(partID)=std(part(:,8));
    m(partID)=mean(part(:,11));
    s(partID)=std(part(:,11));
    
    A=
    
end 

[Murstoe]

Guys I’m so sorry I don’t know what happened to it. I will sure fix it. I apologise again

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[Turlough Hughes]

You could do it as follows:

xlsData = xlsread('PartS_all.xlsx');
partID = xlsData(:,4);
uPartID = unique(partID).'; % Unique part IDs

% Preallocate space
c = 0; 
A = zeros(numel(uPartID),5);

for currPartID = uPartID
    c = c+1; 
    part = xlsData(xlsData(:,4) == currPartID,:); %edit
    A(c,:) = [currPartID mean(part(:,8)) std(part(:,8)) mean(part(:,11)) std(part(:,11))];
end

[Murstoe]

I get the following error:

Index in position 2 exceeds array bounds (must not exceed 1).

Error in Untitled (line 25)

A(c,:) = [currPartID mean(part(:,8)) std(part(:,8)) mean(part(:,11)) std(part(:,11))];

[Turlough Hughes]

I made a mistake. It should work fine now.