[processing] log cases when subset is smaller than requested number of

features

(cherry-picked from b72f5d1)

python/plugins/processing/algs/qgis/RandomExtractWithinSubsets.py

@@ -125,9 +125,12 @@ def processAlgorithm(self, parameters, context, feedback):
             classes[attrs[index]].append(feature)
             feedback.setProgress(int(i * total))
 
-        for subset in classes.values():
+        for k, subset in classes.items():
             selValue = value if method != 1 else int(round(value * len(subset), 0))
-            selran.extend(random.sample(subset, min(selValue, len(subset))))
+            if selValue > len(subset):
+                selValue = len(subset)
+                feedback.reportError(self.tr('Subset "{}" is smaller than requested number of features.'.format(k)))
+            selran.extend(random.sample(subset, selValue))
 
         total = 100.0 / featureCount if featureCount else 1
         for (i, feat) in enumerate(selran):

python/plugins/processing/algs/qgis/RandomSelectionWithinSubsets.py

@@ -133,12 +133,15 @@ def processAlgorithm(self, parameters, context, feedback):
                 feedback.setProgress(int(i * total))
 
             selran = []
-            for subset in classes.values():
+            for k, subset in classes.items():
                 if feedback.isCanceled():
                     break
 
                 selValue = value if method != 1 else int(round(value * len(subset), 0))
-                selran.extend(random.sample(subset, min(selValue, len(subset))))
+                if selValue > len(subset):
+                    selValue = len(subset)
+                    feedback.reportError(self.tr('Subset "{}" is smaller than requested number of features.'.format(k)))
+                selran.extend(random.sample(subset, selValue))
 
             layer.selectByIds(selran)
         else: