Changeset 8829

Timestamp:

10/22/12 16:12:32 (12 years ago)

Author:

gkronber

Message:

#1902: fixed an issue that occurs in scaling if a variable is effectively constant in the training partition

File:

• trunk/sources/HeuristicLab.Algorithms.DataAnalysis/3.4/Linear/Scaling.cs (modified) (2 diffs)

trunk/sources/HeuristicLab.Algorithms.DataAnalysis/3.4/Linear/Scaling.cs

@@ -44 +44 @@
       foreach (var variable in variables) {
         var values = ds.GetDoubleValues(variable, rows);
-        var min = values.Min();
-        var max = values.Max();
+        var min = values.Where(x => !double.IsNaN(x)).Min();
+        var max = values.Where(x => !double.IsNaN(x)).Max();
         scalingParameters[variable] = Tuple.Create(min, max);
       }
@@ -57 +57 @@
       double min = scalingParameters[variable].Item1;
       double max = scalingParameters[variable].Item2;
-      return ds.GetDoubleValues(variable, rows).Select(x => (x - min) / (max - min));
+      if (min.IsAlmost(max)) return rows.Select(i => 0.0); // return enumerable of zeros
+      return ds.GetDoubleValues(variable, rows).Select(x => (x - min) / (max - min));  // scale to range [0..1]
     }