How to sort a matrix's columns by using indexes
25 views (last 30 days)
Show older comments
I wrote some codes to sort an array (a) descendingly. I want to use the indexes (indA) to sort the data matrix's columns.
close all;
clc
load lung.mat
data=lung;
[n,m]=size(data);
l=1;
t=1;
data1=[];
data2=[];
for i=1:n
if data(i,m)==1
data1(l,:)=data(i,:);
l=l+1;
else
data2(t,:)=data(i,:);
t=t+1;
end
end
if t>l
data1(l:t-1,:)=0;
else
data2(t:l-1,:)=0;
end
for i=1: m
thisCol1=data1(:,i);
thisCol2=data2(:,i);
a(i)=fHammingDist(thisCol1,thisCol2);
end
[A,indA]=sort(a,'descend');
I'll be very greatfull to have your opinions how to sort a matrix's columns by using an array of indexes.
Thank you
1 Comment
Bruno Luong
on 25 Aug 2019
Edited: Bruno Luong
on 25 Aug 2019
Are you sure to compute the distance of the last column which seems to contain special values
...
if data(i,m)==1
...
end
...
for i=1: m
...
a(i)=fHammingDist(thisCol1,thisCol2);
end
Answers (2)
Bruno Luong
on 25 Aug 2019
Short answer
data = data(:,indA);
Long answer
load lung.mat
data=lung;
b = data(:,end) == 1;
data1 = data(b,:);
data2 = data(~b,:);
n1 = size(data1,1);
n2 = size(data2,1);
if n1 < n2
data1(n2,1) = 0;
elseif n2 < n1
data2(n1,1) = 0;
end
a = arrayfun(@(j) fHammingDist(data1(:,j),data2(:,j)), 1:size(data,2));
[A,indA] = sort(a,'descend');
data1 = data1(:,indA);
data2 = data2(:,indA);
data = data(:,indA);
0 Comments
dpb
on 25 Aug 2019
Edited: dpb
on 25 Aug 2019
See
doc sortrows
Not clear which array it is you wish sorted but mayhaps can accomplish directly -- altho the auxiliary array and distances may be needed to have been computed, not knowing exactly the problem trying to solve.
But, given the index vector you've built, simply
A=A(indA,:);
if we presume this mystery array is 'A' will rearrange rows in that order.
ERRATUM:
As Bruno points out, I mixed metaphors/switched horses midstream...
A=A(:,indA);
to sort the columns instead, of course.
2 Comments
See Also
Categories
Find more on Shifting and Sorting Matrices in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!