Revision: 17815
http://sourceforge.net/p/gate/code/17815
Author: adamfunk
Date: 2014-04-11 13:55:26 +0000 (Fri, 11 Apr 2014)
Log Message:
-----------
Prevent division by zero; fix bug #144.
Modified Paths:
--------------
gate/trunk/src/main/gate/util/ClassificationMeasures.java
Modified: gate/trunk/src/main/gate/util/ClassificationMeasures.java
===================================================================
--- gate/trunk/src/main/gate/util/ClassificationMeasures.java 2014-04-11
13:27:42 UTC (rev 17814)
+++ gate/trunk/src/main/gate/util/ClassificationMeasures.java 2014-04-11
13:55:26 UTC (rev 17815)
@@ -318,6 +318,7 @@
sum += confusionMatrix[j][i];
marginalArrayR[i] = sum;
}
+
// Compute Cohen's p(E)
float pE = 0;
if(totalSum > 0) {
@@ -325,10 +326,15 @@
for(int i = 0; i < numCats; ++i)
pE += (marginalArrayC[i] * marginalArrayR[i]) / doubleSum;
}
+
// Compute Cohen's Kappa
- if(totalSum > 0) // FIXME: division by zero when pE = 1
- kappaCohen = (observedAgreement - pE) / (1 - pE);
+ if (pE == 1.0F) { // prevent division by zero
+ kappaCohen = 1.0F;
+ }
+ else if (totalSum > 0)
+ kappaCohen = (observedAgreement - pE) / (1.0F - pE);
else kappaCohen = 0;
+
// Compute S&C's chance agreement
pE = 0;
if(totalSum > 0) {
@@ -338,9 +344,14 @@
pE += p * p;
}
}
- if(totalSum > 0) // FIXME: division by zero when pE = 1
- kappaPi = (observedAgreement - pE) / (1 - pE);
+
+ if (pE == 1.0F) { // prevent division by zero
+ kappaPi = 1.0F;
+ }
+ else if (totalSum > 0)
+ kappaPi = (observedAgreement - pE) / (1.0F - pE);
else kappaPi = 0;
+
// Compute the specific agreement for each label using marginal sums
float[][] sAgreements = new float[numCats][2];
for(int i = 0; i < numCats; ++i) {
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