Hi,
I just registered as ckling at sourceforge and would like to register as
a octave-forge developer . I would like to submit a bugfix for the
kmeans.m of the statistics package:
In cases where clusters contain only one element, the mean() function
for calculating the new center of the cluster will not return the true
center, but will return the mean() of all coordinates of the single
cluster element.
I fixed that issue and would like to submit the changes.
My changes also include the correction of two mistypings, additionally I
renamed the variable index to idx (for not confusing it with the
function index) and I removed the unnecessary check for
length(mean(...)) in the check for empty clusters.
Here is the output of diff:
## Classify
[tmp, classes] = min (D, [], 2);
- ## Calcualte new centroids
+ ## Calculate new centroids
for i = 1:k
## Check for empty clusters
- if (sum (classes == i) ==0 || length (mean (data(classes == i,
:))) == 0)
+ if (sum (classes == i) ==0)
switch emptyaction
## if 'singleton', then find the point that is the
@@ -94,10 +94,11 @@
endif ## end check for empty clusters
## update the centroids
- centers(i, :) = mean (data(classes == i, :));
+ elements_class = data(classes == i, :);
+ centers(i, :) = sum(elements_class,1)/size(elements_class,1);
endfor
- ## calculate the differnece in the sum of distances
+ ## calculate the difference in the sum of distances
err = sumd - objCost (data, classes, centers);
## update the current sum of distances
sumd = objCost (data, classes, centers);
@@ -112,11 +113,11 @@
endfor
endfunction
-function index = maxCostSampleIndex (data, centers)
+function idx = maxCostSampleIndex (data, centers)
cost = 0;
- for index = 1:rows (data)
- if cost < sumsq (data(index,:) - centers)
- cost = sumsq (data(index,:) - centers);
+ for idx = 1:rows (data)
+ if cost < sumsq (data(idx,:) - centers)
+ cost = sumsq (data(idx,:) - centers);
endif
endfor
endfunction
Cheers,
Christoph
--
Dipl.-Inf. Christoph Carl Kling
WeST - Institute for Web Science and Technologies
University of Koblenz-Landau, Germany
http://west.uni-koblenz.de
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