MATLAB: Linearly spacing a nX1 matrix

linspacing with condition

Hi!

I have an nx1 matrix. I want to linearly divide the value in each row into 16 columns thus giving me a nx16 linearly spaced matrix.

For a little example let us say I have a=[45; 50] now I want to creat a 2×4 matrix such that the values in consecutive clolumns are linearly spaced and their sum is equal to 45. Could someone help on this one please?

Best Answer

Your problem is still under-specified, and an infinite number of matrices will meet you conditions. Here is one possible solution:

a = [45; 50];
numberColumns = 4;
aMat = a + [0:numberColumns-1];
aMat = (aMat - mean(aMat,2) + a)/numberColumns;

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MATLAB: How to create vector after import data from .xls using for loops

Thank everyone for trying to help me, but I find solution by my self. Maybe is little complicated, but it works, and that is most important... :)

I use "xlsread" command to import data from excel and I get matrix x1, then I use for loop to get my new matrix x2.

Code:

    x2=zeros(13,7);
% caunters
m=1; n=1; t=1;
for k=m:length(x1)
    if x1(k,:)~=100
        x2(t,n)=x1(k,1);
        t=t+1;
    else if (x1(k,:)==100 && (x1(k+1,:)==100 && x1(k+2,:)==100))
            m=k+3;
            n=n+1;
            t=1;
            continue
        end
    end
end

MATLAB: Extract portion of netCDF file based on latitide and longitude

Try using ncdisp first to look at the structure of your file. Usually, netcdf files have data defined on 'dimension' variables - lat and lon. So you would first read the lat and lon variables from the file ( ncread ).

 >> lon = ncread('/tmp/example.nc','longitude')'
 lon =
Columns 1 through 11
104.1250  104.3750  104.6250  104.8750  105.1250  105.3750  105.6250  105.8750  106.1250  106.3750  106.6250
Columns 12 through 13
106.8750  107.1250
 >> lat = ncread('/tmp/example.nc','latitude')'
 lat =
Columns 1 through 11
    8.1250    8.3750    8.6250    8.8750    9.1250    9.3750    9.6250    9.8750   10.1250   10.3750   10.6250
Column 12
   10.8750

You would then have to find the indices into lat and lon variables within which your grid lies. Use FIND to locate those indices:

>> latstart = find(lat>9.84,1, 'first')
latstart =
       8
>> latend = find(lat<10.02,1, 'last')
latend =
       8

Once you get these start/end indices to each of your variable dimension, you can use the partial read capability of NCREAD to read from your 'r' variable.

If you have to do this kind of operation frequently, consider wrapping this logic in a function.

(Note - have a look at the linked functions and examples. Give it a try and post back if you have trouble adapting this idea).

Best Answer

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MATLAB: How to create vector after import data from .xls using for loops

MATLAB: Extract portion of netCDF file based on latitide and longitude

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