Can anyone please explain me this line of a code?

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jasmine 2019-6-7

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评论： jasmine 2019-6-7

采纳的回答： Stephen23

probability = arrayfun(@(x) mean(audR(audR(:,1)==x,2)==2) , contrast);

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Adam Danz 2019-6-7

编辑：Adam Danz 2019-6-7

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Ahhh... yeah it's an array (blush).

@Iuliana,

audR(:,1)==x %this produces a logical index marking rows of the first 
             %column of audR that match the input value 'x'

audR(audR(:,1)==x,2) % for each of those rows from the comment above,
                     % you're extracting the data from the second 
                     % column of audR.  

(audR(audR(:,1)==x,2)==2) %and finally, you're determining whether those
                          % values are equal to 2.

Here's an example you can execute line by line to see what's going

% Produce fake data
audR = [[1;1;2;2;3;3],[1;2;1;2;1;2]]; 
x = 2 
audR(:,1)==x                    
audR(audR(:,1)==x,2) 
(audR(audR(:,1)==x,2)==2) 

jasmine 2019-6-7

Thank you very much for your answer!

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Stephen23 2019-6-7

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编辑：Stephen23 2019-6-7

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If audR is a matrix, then

audR(audR(:,1)==x,2)==2
%    ^^^^^^^^^           % first column of audR
%             ^^^        % ... is equal to x.
%    ^^^^^^^^^^^^        % used as a logical index into the rows of audR
%                 ^      % second column of audR
%                   ^^^  % ... is equal to 2.

So the code takes the rows of audR where the first column equals x, and checks if their second column equals 2.