Extracting data from a 'for' loop

I have the following input file 'Test_14-Dec-2018.xls' attached

This is my code:

clc;
clear;
dataset = xlsread('Test_14-Dec-2018');
A = dataset(:,1:8);
B = A(A(:,1)==10,:); %for a=10s
k=1;
C=cell(1,4);
for p = 1:4
    j=p*9;
    i=j-8;
    C{k} = B(i:j,:);
    d=cell2mat(C);
    x = d(:,2);
    k=k+1;

end

Basically what the code does is extract that data into the matlab workspace and selects the data only when the first column has '10' data.

In the for loop, every 9 rows are selected and assigned a cell so that I have 9x8 in each 4 cells.

Cell2mat converts those cells into one matrix of 9x32. I am able to extract the second column from that.

Now, I want the data from every 8th column i.e. d(:,8), d(:,16), d(:,24), d(:,32) in a for loop but I am unable to do that.

After that I should be able to plot 'x' with each of those data from each column.

Any kind of help will be appreciated.

[Bob Thompson]

What do you mean by, "I am unable to do that?" Have you run into some kind of error? Do you not know the commands necessary? Or do you not know the exact formulation for such a task?

[Yoham Parelkar]

I tried with using another for loop:

for l =1:32
    y=d(:,l);
    l=l+8;
end

Doing this, only d(:,32) gets saved in the workspace. I am not able to store the data from d(:,8), d(:,16), d(:,24)

[Bob Thompson]

You're unable to save more than d(:,32) because you're overwriting y each time you run the loop. If you want to save each result from a loop you should index your result. A better way of doing this would be the following.

y = d(:,[8,16,24,32]);

[Yoham Parelkar]

See that's the thing,

I have mentioned till 32 since that's according to the input file attached

In future, I wouldn't know the exact dimensions of the dataset I would get in the workspace with any input file and that is why I am trying for a 'for' loop so that I don't have to alter my script each time for a different input file.

Thanks for replying so promptly though!

[Bob Thompson]

for i = 1:floor(size(d,2)/8);
    y(:,i) = d(:,i*8);
end

Try that.

[Yoham Parelkar]

Again, it saves only the last column values i.e. column 32

[Image Analyst]

Bob, again, please, answers down below in the answers section, not up here in the comments section.

[Bob Thompson]

Ha, you are correct, I had an error. It has been fixed now.

[Yoham Parelkar]

Thanks Bob for fixing the error.

Now I want to plot multiple values of 'y' with 'x'.

    plot(x,y(:,m))

Adding the above line only gives me comparison of x with obly one value of 'y'. How should I edit the code in such a way that all values of 'y' gets plotted with 'x'?

[Bob Thompson]

You need to set 'hold on'. That will allow you to plot multiple lines on the same figure. You can do this before the loop.

Answer 1

[Yoham Parelkar]

Thank you Bob and Madhan Ravi for your help and inputs!

I was able to successfuly plot and further add new commands and complete the script.

This is correct code:

clc;
clear;
dataset = xlsread('Test_14-Dec-2018');
A = dataset(:,1:8);
B = A(A(:,1)==10,:); %for a=10s
k=1;
C=cell(1,4);
for p = 1:4
    j=p*9;
    i=j-8;
    C{k} = B(i:j,:);
    d=cell2mat(C);
    x = d(:,2);
    k=k+1;
end
for m = 1:floor(size(d,2)/8);
    y(:,m) = d(:,m*8);
    hold on
    plot(x,y(:,m))  
end

Answer 2

[madhan ravi]

Replying to your latter comment :

y=cell(1,numel(1:8:32));
for l=1:8:32
    y{l}=d(:,l);
end
celldisp(y) % [y{:}] to convert it to double from cell
y=d(:,[1:8:32])

[Yoham Parelkar]

Thank for the reply!

Although I mentioned it wrong in the first place, I altered your code to:

y=cell(1,numel(8:8:32));
for l=8:8:32
    y{l}=d(:,l);
end
celldisp(y) % [y{:}] to convert it to double from cell
y=d(:,[8:8:32])

I will try to complete the script and will revert to you.

[madhan ravi]

Anytime :) , if my code worked make sure to accept the answer else let know what needs to be done after you analyse(take your time) let me take a short nap by then ;-).

[Yoham Parelkar]

Well actually, your code only extracts every 8th column and saves those 4 columns into a new variable which is nothing but the same as of 'd' variable.

I don't want to make a new dataset of those values but only extract those columns and plot it with 'x'