MATLAB: How to plots a data file by just using 10 points from each decade

plotnpointsfromeachdecade

For example, a data file has 2 column, in column 1 we have [1:1:10000] and in y-axis some experimental value. I would like to get a 'log-log' plots with only 10 points from each decade, like 1, 2,… 10, 20, …., 100, 200, …., 1000, 2000, ….. 10000 and the corresponding y values. This way instead of plotting 10000 points I will only plot 40 points and we will have exactly similar looking curve in log-log plot.

Best Answer

This should work to create your vector of indices:

idx = bsxfun(@times, [1:10]', logspace(0,3,4));
idx = unique(fix(idx(:)));
idx =
           1
           2
           3
           4
           5
           6
           7
           8
           9
          10
          20
          30
          40
          50
          60
          70
          80
          90
         100
         200
         300
         400
         500
         600
         700
         800
         900
        1000
        2000
        3000
        4000
        5000
        6000
        7000
        8000
        9000
       10000

You could do this in one line, but there is no advantage to that, and it makes the code more difficult to read.

Related Solutions

MATLAB: How to get decade means of monthly 3D satellite data

Do you want a single temperature for each decade, or you you want an average for each lat/lon coordinate pair?

I wasn't able to get splitapply or groupsummary to work with a 3D dataset, but I was able to achieve group means with a for-loop.

The challenge here is perhaps identifying the groups. I want to convert your time variable to a datetime so I can group by year. The following code allows we to inspect the attributes of time.

info = ncinfo('keeganCarvalho_bob.nc')

From here, I can see that time is the number of days since 1800-1-1 00:00:00, and that

is 1 day. I performed the convertion with the following code.

dTime = datetime(1800,1,1)+days(time)

I then extracted the year and used the discretize function to group the years into your specified bins.

yr = year(dTime);
G = discretize(yr,[1986 1996 2006 2016 2019]);

All that is left is to get the mean.

for d = 1:max(G)
    decadeMean(d) = mean(temp(:,:,G==d),"all");
end
plot(decadeMean)

If instead you want the mean for each lat/lon location, you could try something like this. You'd have to change the plotting code to be something appropriate for matrix data.

for d = 1:max(G)
    decadeMean(:,:,d) = mean(temp(:,:,G==d),3);
end
% rearrange data so decade means are in rows, and columns are lat/lon pairs
plot(reshape(permute(decadeMeanLL,[3,1,2]),max(G),[]))

MATLAB: Finding and counting of identical rows in a matrix

For Octave?

M = [ 1 300 3500 500 6000
 3 200 3000 500 6500
 5 150 2500 450 6000
 8 400 2000 550 5500
 5 200 3000 500 6500
 9 150 2500 450 6000
 2 200 3000 500 6500];
[a,b,c] = unique(M(:,2:end),'rows','first');
[~,i] = sort(b);
[~,ii] = sort(i);
out = [accumarray(ii(c),M(:,1)), a(i,:)];

Here use Octave 5.1.0

Best Answer

Related Solutions

MATLAB: How to get decade means of monthly 3D satellite data

MATLAB: Finding and counting of identical rows in a matrix

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