Fix zero division error (classifying 'empty' docs)

When a document that produced as a classification result all-zero
vectors, a ZeroDivision error was thrown. On the Live Test this error
produced an infinity loop freezing the browser's Live Test tab, this was
due to zero division producing NaN instead of throwing an exception
which made the while loop condition never false (e.g. writing "=" as an
input document with a model with more than 2 categories will freeze the
Live Test tab).

pyss3/__init__.py

@@ -2330,8 +2330,10 @@ def kmean_multilabel_size(res):
                 clust["neg"].append(cat_cv)
             else:
                 clust["pos"].append(cat_cv)
-        new_cent_neg = sum(clust["neg"]) / len(clust["neg"])
-        new_cent_pos = sum(clust["pos"]) / len(clust["pos"])
+        if len(clust["neg"]) > 0:
+            new_cent_neg = sum(clust["neg"]) / len(clust["neg"])
+        if len(clust["pos"]) > 0:
+            new_cent_pos = sum(clust["pos"]) / len(clust["pos"])
     return len(clust["pos"])
 
 

pyss3/resources/visual_classifier/index.html

@@ -269,11 +269,11 @@ <h5 style="margin-top: 0;">
                 <span ng-show="ss3.cvns[0][2] < .75" class="grey-text">
                   [ more evidence is required <span ng-show="ss3.cvns[0][2] > .25">but if I had to guess, I would say <span class="pink-text">{{ss3.ci[ss3.cvns[0][0]]}}</span></span> ]
                 </span>
-                <span style="display:inline-block" ng-if="ss3 && is_cat_active(ss3.cvns[0])">
+                <span style="display:inline-block" ng-if="ss3 && is_cat_active(ss3.cvns[0]) && ss3.cvns[0][2] >= .75">
                   <span class="pointer pulse" ng-style="{'opacity': ss3.cvns[0][1]}" ng-click="select_cat(ss3.cvns[0][0])">{{ss3.ci[ss3.cvns[0][0]]}}</span>
                 </span>
               </h5>
-              <h5 ng-if="ss3 && ncats > 2 && is_cat_active(ss3.cvns[1])">
+              <h5 ng-if="ss3 && ncats > 2 && is_cat_active(ss3.cvns[1]) && ss3.cvns[0][1]">
                 <span style="color: black">
                   <span ng-show="ss3.cvns[1][1] < .25">Hmmm...Just Guessing...</span>
                   <span ng-show="ss3.cvns[1][1] < .5">Maybe </span>

pyss3/resources/visual_classifier/js/app.js

@@ -277,8 +277,10 @@ app.controller("mainCtrl", function($scope) {
           active_cats.push(cats[i][0]);
         }
       }
-      new_cent_neg = clust.neg.reduce((a,b) => a + b, 0) / clust.neg.length;
-      new_cent_pos = clust.pos.reduce((a,b) => a + b, 0) / clust.pos.length;
+      if (clust.neg.length > 0)
+        new_cent_neg = clust.neg.reduce((a,b) => a + b, 0) / clust.neg.length;
+      if (clust.pos.length > 0)
+        new_cent_pos = clust.pos.reduce((a,b) => a + b, 0) / clust.pos.length;
     }
     return active_cats;
   }