mink and maxk functions

I'm using MATLAB R2017a. While trying to use "mink" and "maxk" functions, the MATLAB responds "Undefined function or variable 'maxk'." These two functions were introduced in R2017b. Is it possible to use these functions with R2017a? if yes, then how?

[Stephen23]

"These two functions were introduced in R2017b. Is it possible to use these functions with R2017a?"

No.

Answer 1

[Birdman]

One approach would be writing your own function:

function y=mink(A,k)
A=sort(unique(A));
y=A(1:k);
end

Call this function from command line as follows

A=1:10;
mink(A,3)

and the first three smallest elements will be displayed.

[UET Hussain]

Its good. Thank you for response. What about maximum values? mink(A,3) will simply give me the first three values of my array. how to get the last 3?

[Stephen23]

The output of unique is already sorted, so sort is unnecessary.

[Birdman]

function y=maxk(A,k)
A=sort(unique(A),'descend');
y=A(1:k);
end

and then from command line:

A=1:10;
maxk(A,3)

[UET Hussain]

Got it...... @Birdman Thank you Sir.

[Birdman]

You are welcome. You can officially thank me by accepting my answer.

[Jan]

mink does not reply unique elements. Therefore the correct replacement is:

function y = mink(A, k)
A = sort(A);   % No UNIQUE here
y = A(1:k);
end

See: mink([1,1,2,3], 2) replies [1,1,2] .

[Birdman]

Mine approach was different, but anyway thanks Jan :)

Answer 2

[Salam Ismaeel]

% function [B BIndex RestVector]= maxk2(A, k)
% Find k largest elements in a Vector A
% B : Vector with all max elements (included repeated) 
% BIndex : idx of max k element 
% RestVector : rest of the elements without max k elements 

function [B BIndex RestVector]= maxk2(A, k)
B = 0;
RestVector = A;
sumIndex = 1;
for i=1:k
  MaxA = max(A);
  I = A == MaxA;
  sumI = sum(I); %To find number of Max elements (repeated) 
  B(sumIndex: sumIndex+sumI-1) = MaxA; % to same max elements in B
  BIndex(sumIndex: sumIndex+sumI-1) = find(A == MaxA); 
  sumIndex = sumIndex + sumI; 
  A(I) = min(A); % exchange the max elements by a smallest value  
end
RestVector(BIndex) = [];  % remove largest values

------------------------------ Example ------------------
>> x
x =
     4    17    65    73    65    45    55    30    74    19
>> [x1 x1idx x1new ] = maxk2(x,4)
x1 =
    74    73    65    65    55
x1idx =
     9     4     3     5     7
x1new =
     4    17

[UET Hussain]

Sir Sir Sir, slightly difficult approach. but its giving all required things. thanks for response.