Seperate column into more columns: 90740x1 double array into 1511x64 something array

Hello

i have a set of data 90740x1 double. meaning:

what i really want this to do is make a new matrix where i read every 1511 data from this row into a new row. example:

so from 1 to 1511 in column 1 in the new matrix...and from 1511 to 3023 into column 2 in the new matrix etc. etc.

i made a code, it only works for the first 1511 data but after that it displays an error about dimension.

n = 1; for i=1:length(kwh) kunder(:,1) = kwh(1:n:1511); end

so when u put: kunder(:,1) = kwh(1511:n:3023); under the first kunder it displays dimension error...

please help me figure this out..as i want to plot the 24 hour kwh usage data of customers consumption of electricity.

thank you

Answer 1

[Kelly Kearney]

Your code is erroring because of mismatched dimensions; when n = 2, 1:n:1511 expands to [1 3 5 ... 1511], which is only 756 elements in length. What you wanted was [1:1511]+1511*(n-1). But it would be more straighforward just using reshape.

x = rand(90740,1);
nrow = 1511;
ncol = ceil(length(x)/nrow);
x = [x; nan(ncol*nrow-length(x),1)];
x = reshape(x,nrow,ncol);

Note that you need to pad with NaNs or 0s or whatever is appropriate, since your number of elements isn't evenly divisible by 1511.

[awda]

Thank you, it really did work, it helped me :)

there is a small problem i dont understand now: when i divide 90740/1511 i should get 64 columns with 34 more data in the last part..but now i get 300+ more data in the column 65..with nan in the end.. any ideas if it is dividing the Column correctly or adding random data in ?

[Kelly Kearney]

How do you figure that? 90740/1511 = 60.053, ie. 60 remainder 80. So you should end up with a 1511 x 61 array, with 80 elements in the final column.

Answer 2

[Azzi Abdelmalek]

Use reshape

reshape(A,1511,64)

[awda]

thanks for answering :) but i get an error:

Error using reshape To RESHAPE the number of elements must not change.

[Azzi Abdelmalek]

This is because with 90740 elements you can't get a 1511x64 array which contains 96704 element

[Azzi Abdelmalek]

What you can do is to add some nan to your final array

n=90740
A=rand(n,1);
m=ceil(90740/1511)*1511
A(end+1:m)=nan
out=reshape(A,1511,[])