Importating Data from Excell

Suppose I want to read the third column of data from an Excel sheet.

the format of the data increments every 5 ms.

0 5 10 15 ... ... 995 0 5 10 15 ... ... 995

Then after 995, it goes back to 0. There are about 80,000 entries. How can I make the vector accumulate rather than reset once it reaches 1000?

Thanks

[Iain]

Errr, do you want to know:

How to read the third column from an excel sheet? How to make excel's third column increment in 5ms steps from 0 to some upper limit? How to make matlab create a column that increments in 5ms steps from 0 to some upper limit?

[T]

Well there are two columns of interest.

The number of elements in each column is say 86,000.

in column two I time as described above, and the third column I have measured data.

If I want to construct a new time [0, 5, .... ] (up to 86,000 entries, can I still associate that time with each element in the third column?

Answer 1

[Azzi Abdelmalek]

% Example

a=0:5:995;
a=repmat(a,1,5)';  % your array
%-------------------------------
b=reshape(a,numel(0:5:995),[]);
[n,m]=size(b);
c=1000*(0:m-1);
out=bsxfun(@plus,b,c);
out=out(:)

[T]

I could just use a = 0:5:86000 ?

Then how would be able to associate each element in the third column with each element in a ?

[Azzi Abdelmalek]

If M is your 86000x3 matrix

c3=M(:,3);
C2=0:5:(numel(c3)-1)*5;
plot(c2,c3)

[T]

Sorry, why *5? The frequency 5 is 5 milliseconds, then I would need to convert the entire array to just seconds.

[Azzi Abdelmalek]

You can adapt it yourself:

c3=M(:,3);
C2=0:0.005:(numel(c3)-1)*0.005;
plot(c2,c3)

Answer 2

[Iain]

 third_col = xlsread(filename, sheet#, 'C:C')';
 times = 0:5:((86000-1)*5);

 plot(times,third_col)

The "n"th part of third_col happens at the "n"th time in times...