warn with 0 or negative values when using log scale in graduated rend…

…erer (#38138) Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
qgis · Aug 4, 2020 · 51f3c7e · 51f3c7e
1 parent afaccb6
commit 51f3c7e
Showing 1 changed file with 12 additions and 1 deletion.
diff --git a/src/core/classification/qgsclassificationlogarithmic.cpp b/src/core/classification/qgsclassificationlogarithmic.cpp
@@ -110,9 +110,20 @@ QList<double> QgsClassificationLogarithmic::calculateBreaks( double &minimum, do
 QString QgsClassificationLogarithmic::valueToLabel( double value ) const
 {
   if ( value <= 0 )
+  {
     return QString( QStringLiteral( "%1" ) ).arg( value );
+  }
   else
-    return QString( QStringLiteral( "10^%1" ) ).arg( std::log10( value ) );
+  {
+    if ( std::isnan( value ) )
+    {
+      return QObject::tr( "invalid (0 or negative values in the data)" );
+    }
+    else
+    {
+      return QString( QStringLiteral( "10^%1" ) ).arg( std::log10( value ) );
+    }
+  }
 }
 
 QString QgsClassificationLogarithmic::labelForRange( double lowerValue, double upperValue, QgsClassificationMethod::ClassPosition position ) const