How to find the index of top k max values in the matrix

A=[ 5 40 10 9 2 1 8 12 33 23]

find index of top 3 max values as:B= [ 2 9 10]

and return the rest index value in another array C=[1 3 4 5 6 7 8]

Thank you.

Answer 1

[Bruno Luong]

>> A=[ 5 40 10 9 2 1 8 12 33 23]

A =

     5    40    10     9     2     1     8    12    33    23

>> [~,B]=maxk(A,3)

B =

     2     9    10

>> C=setdiff(1:length(A),B)

C =

     1     3     4     5     6     7     8

[Hang Vu]

Thank you so much!

[madhan ravi]

Hang: Did you even try my answer?? Which was given even before this answer. It shouldn't be hard to copy paste an answer.

[Hang Vu]

Thank you! I did try and it did not work... I am sorry if I did anything wrong make you upset?! and the above answer has 2 lines only.

[madhan ravi]

"it did not work" - doesn't describe anything useful , what error message did you get? There's nothing to be upset of , just curious what could have gone wrong.

"and the above answer has 2 lines only." - lol , pasting one extra one line of code wouldn't do any harm. In fact maxk() was introduced in 2017b, that's why sort() was used, in fact when you ask a question next time make sure to fill up the field Release to mention which version of MATLAB you're using.

>> A=[ 5 40 10 9 2 1 8 12 33 23]

A =

     5    40    10     9     2     1     8    12    33    23

>> [~,idx]=sort(A,'descend');
>> B=idx(1:3)

B =

     2     9    10

>> C=setdiff(idx,B) 

C =

     1     3     4     5     6     7     8
>> 

[Bruno Luong]

SORT method should also work. But it does not use the best method for what is required.

[Hang Vu]

I am sorry, my mistake. I didn't mention about the version. I did say "Thank you" to your work at the same time I accepted another answer. really I don't know why you are angry like that...

[madhan ravi]

There's no need to be sorry. By the way, you haven't justified your statement "it did not work".

[Hang Vu]

>> A=[ 5 40 10 9 2 1 8 12 33 23]

A =

     5    40    10     9     2     1     8    12    33    23

>> [~,idx]=sort(A,'descend')
Insufficient number of outputs from right hand side of equal sign to satisfy assignment.

sort function does not work, I tried many time. As you mentioned above, it may be because of the version...

[madhan ravi]

Alright , thank you :)

[Hang Vu]

Thank you so much for the help! and your time also.

Answer 2

[madhan ravi]

[~,idx]=sort(A,'descend');
B=idx(1:3)
C=setdiff(idx,B) 

[Hang Vu]

Thank you!