how can i compute std 2d

Hi

iwould like to ask how can i obtain std along all the rows and columns as culored image that explain the values of std

the matrix dimension is 51 71 any suggestion ?

thanks

[Walter Roberson]

Could you give an example of what you would like the output to look like?

[RADWAN A F ZEYADI]

like this image that explain the std

Answer 1

[Walter Roberson]

data = randn(51, 71).*rand(51,71);   %just some data

std_along_columns = std(data, [], 1);  %one result for each column
std_along_rows = std(data, [], 2);     %one result for each row
std_overall = std(data(:));            %over entire array

whos

  Name                    Size            Bytes  Class     Attributes

  data                   51x71            28968  double              
  std_along_columns       1x71              568  double              
  std_along_rows         51x1               408  double              
  std_overall             1x1                 8  double              

[RADWAN A F ZEYADI]

thank you but can i plot them in matrix that explain different colors of std

[Walter Roberson]

You cannot. std means standard deviation which is property of groups of data, not of individual points. For example you can take the standard deviation along the rows and do a line plot of that.

In order to have a 2 dimension array of standard deviation results, you would have need to have started with a 3D array. For example,

cmap = flipud(hot(64));

data = sort(randn(51, 71, 83) .* rand(51, 71, 83),1);   %just some data
s = std(data, [], 3);
imagesc(s); colormap(cmap)
colorbar()