Creating Matlab Median Function

sum1 · #1 $Old$ October 26th, 2009, 10:39 PM

I first entered the code
function k=mymedian(p)
Now I have to sort the vecotr and find out how to type it out so that I can receive the median of a vector.
Does anybody understand this problem?

elbarto · #2 $Old$ October 26th, 2009, 10:50 PM

do you mean:

Code:

k=mymedian(sort(p))

elbarto · #3 $Old$ October 26th, 2009, 11:29 PM

you may also be interested in this if you dont want to use the standard matlab "sort" function.

Re-ordering a vector... (MATLAB)

Regards Elbarto

sum1 · #4 $Old$ October 26th, 2009, 11:52 PM

Thanks for the help I solved it by using the following code
function k=mymedian(p)
w=sort(p);
r=length(w);
g=floor(r/2);
k=w(g+1);
if(g*2==r)
k=(w(r)+ k)/2;
end

Does anybody have ideas on how to do the same concept for a matrice?

elbarto · #5 $Old$ October 27th, 2009, 12:36 AM

change

Code:

w=sort(p);

to

Code:

w=sort(p(:));

Code is untested but should work.

Elbarto

CaptainBlack · #6 $Old$ October 27th, 2009, 01:17 AM

Quote:

Originally Posted by elbarto $View Post$

change

Code:

w=sort(p);

to

Code:

w=sort(p(:));

Code is untested but should work.

Elbarto

Code:

w=sort(p);

will work just fine.

CB

elbarto · #7 $Old$ October 27th, 2009, 01:54 AM

Quote:

Originally Posted by CaptainBlack $View Post$

Code:

w=sort(p);

will work just fine.

CB

This will return a sorted matrix for "w". The orginal code uses the length function so not all values will be included will they?

@OP, when finding the median of the matrix, do you only want the median of the entire matrix or the median of each column like matlab calculates?

Regards Elbarto

CaptainBlack · #8 $Old$ October 27th, 2009, 10:48 AM

Quote:

Originally Posted by elbarto $View Post$

This will return a sorted matrix for "w". The orginal code uses the length function so not all values will be included will they?

@OP, when finding the median of the matrix, do you only want the median of the entire matrix or the median of each column like matlab calculates?

Regards Elbarto

The op specifies vector repeatedly. If fed a matrix it sorts the columns.

CB

elbarto · #9 $Old$ October 27th, 2009, 05:22 PM

I tried the code in #4 and got the following output:

Code:

DU>> A = magic(5)

A =

    17    24     1     8    15
    23     5     7    14    16
     4     6    13    20    22
    10    12    19    21     3
    11    18    25     2     9

EDU>> mymedian(A)

ans =

    11

EDU>>

It is only returning the median of the first column for me?