Changeset 1254 for cpp/frams/genetics/genooperators.cpp

Timestamp:

06/22/23 03:29:05 (15 months ago)

Author:

Maciej Komosinski

Message:

• turn -0.0 into 0.0 if we have minimum==0.0, so that it does not look as if we got a value below 0.0 (minimum) after mutation (even though -0.0==0.0)
• implemented stochastic rounding for the mutation of integer parameters

File:

• cpp/frams/genetics/genooperators.cpp (modified) (4 diffs)

cpp/frams/genetics/genooperators.cpp

@@ -5 +5 @@
 #include <ctype.h>  //isupper()
 #include <algorithm> // std::min, std::max
+#include <cmath> // std::floor()
 #include "genooperators.h"
 #include <common/log.h>
@@ -203 +204 @@
                 if (result > mx) result = mx - (result - mx); else
                         if (result < mn) result = mn + (mn - result);
-                //wrap (just in case 'result' exceeded the allowed range so much that after reflection above it exceeded the other boundary):
+                //wrap (just in case 'result' exceeded the allowed range so much that after the reflection above it exceeded the other boundary):
                 if (result > mx) result = mn + fmod(result - mx, mx - mn); else
                         if (result < mn) result = mn + fmod(mn - result, mx - mn);
@@ -210 +211 @@
                         //reflect and wrap above may have changed the (limited) precision, so try to round again (maybe unnecessarily, because we don't know if reflect+wrap above were triggered)
                         double result_try = round(result, 3);
-                        if (mn <= result_try && result_try <= mx) result = result_try; //after rounding still witin allowed range, so keep rounded value
-                }
-        }
+                        if (mn <= result_try && result_try <= mx) result = result_try; //after rounding still within allowed range, so keep rounded value
+                }
+        }
+        clipNegativeZeroIfNeeded(result, mn); //so we don't get -0.0 when minimum is 0.0
         return result;
 }
@@ -222 +224 @@
 }
 
-void GenoOperators::setIntFromDoubleWithProbabilisticDithering(ParamInterface &p, int index, double value) //TODO
-{
-        p.setInt(index, (paInt)(value + 0.5)); //TODO value=2.499 will result in 2 and 2.5 will result in 3, but we want these cases to be 2 or 3 with almost equal probability. value=2.1 should be mostly 2, rarely 3. Careful with negative values (test it!)
+void GenoOperators::setIntFromDoubleWithProbabilisticDithering(ParamInterface &p, int index, double value)
+{
+        // Deterministic rounding to the closest integer:
+        //value += 0.5; // value==2.499 will become int 2 and value==2.5 will become int 3, but we want these cases to be 2 or 3 with almost equal probability (stochastic rounding).
+
+        //stochastic rounding (value==2.1 should turn in most cases to int 2, rarely to int 3; value==-2.1 should become mostly int -2, rarely int -3):
+        double lower = std::floor(value);
+        value = rndDouble(1) < (value - lower) ? lower + 1 : lower;
+
+        p.setInt(index, (paInt)value);
 }