How to sort structure arrays in MATLAB?

Question

I\'m working with an image retrieval system using color histogram intersection in MATLAB. This method gives me the following data: a real number which represents the histogram i

Answer 1

Here's one example of how you could do this, using the function MAX instead of having to sort:

%# First, create a sample structure array:

s = struct('value',{1 7 4},'file',{'img1.jpg' 'img2.jpg' 'img3.jpg'});

%# Next concatenate the "value" fields and find the index of the maximum value:

[maxValue,index] = max([s.value]);

%# Finally, get the file corresponding to the maximum value:

maxFile = s(index).file;

EDIT : If you would like to get the N highest values, and not just the maximum, you can use SORT instead of MAX (as Shaka suggested). For example (using the above structure):

>> N = 2;  %# Get two highest values
>> [values,index] = sort([s.value],'descend');  %# Sort all values, largest first
>> topNFiles = {s(index(1:N)).file}  %# Get N files with the largest values

topNFiles = 

    'img2.jpg'    'img3.jpg'

Answer 2

It's also possible to sort the entire structure.

To build off of gnovice's example...

% Create a structure array
s = struct('value',{1 7 4},'file',{'img1.jpg' 'img2.jpg' 'img3.jpg'});

% Sort the structure according to values in descending order
% We are only interested in the second output from the sort command

[blah, order] = sort([s(:).value],'descend');

% Save the sorted output

sortedStruct = s(order);