[chronojump] ForceSensor repetitions cut now discards low force zones at start/end

[Xavier de Blas <xaviblas src gnome org>]

commit 4b8b5babbbe806ae7d9afea2ca513d3f63efabe8
Author: Xavier de Blas <xaviblas gmail com>
Date:   Sun Feb 16 12:32:48 2020 +0100

    ForceSensor repetitions cut now discards low force zones at start/end

 src/forceSensorDynamics.cs | 57 +++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 54 insertions(+), 3 deletions(-)
---
diff --git a/src/forceSensorDynamics.cs b/src/forceSensorDynamics.cs
index 6477a98b..72fd99f3 100644
--- a/src/forceSensorDynamics.cs
+++ b/src/forceSensorDynamics.cs
@@ -193,7 +193,28 @@ public abstract class ForceSensorDynamics
 
        private void prepareCheckAndSendRepetition(int concentricFlag, List<double> yList, int sampleStart, 
int sampleEnd)
        {
-               // 1) remove values to avoid smoothing problems:
+               // 1) remove low force at beginning ot end of the repetition
+               double maxAbs = 0;
+               foreach(double y in yList)
+                       if (Math.Abs(y) > maxAbs)
+                               maxAbs = Math.Abs(y);
+
+               //create List with absolute values
+               List<double> yListAbs = new List<double>();
+               for(int i = 0; i < yList.Count ; i ++)
+                       yListAbs.Add(yList[i]);
+
+               sampleStart = findLocalExtreme(yListAbs, sampleStart, sampleEnd, maxAbs);
+
+               //create List with absolute values reversed to find end of rep
+               List<double> yListAbsRev = new List<double>();
+               for(int i = yListAbs.Count -1; i >= 0 ; i --)
+                       yListAbsRev.Add(yList[i]);
+
+               sampleEnd = yList.Count - findLocalExtreme(yListAbsRev,
+                               yList.Count - sampleEnd, yList.Count - sampleStart, maxAbs);
+
+               // 2) remove values to avoid smoothing problems:
                sampleStart = sampleStart -RemoveNValues -1;
                if(sampleStart < 0)
                        sampleStart = 0;
@@ -202,7 +223,7 @@ public abstract class ForceSensorDynamics
                if(sampleEnd < 0)
                        return;
 
-               // 2) check that end does not outside the after forceSensor.cs cut:
+               // 3) check that end does not outside the after forceSensor.cs cut:
                //    times = times.GetRange(forceSensorDynamics.RemoveNValues -1, times.Count 
-2*forceSensorDynamics.RemoveNValues);
 
                if(sampleEnd >= yList.Count - 2*RemoveNValues)
@@ -211,11 +232,41 @@ public abstract class ForceSensorDynamics
                if(sampleEnd < 0 || sampleStart >= sampleEnd)
                        return;
 
-               // 3) check if displacement is ok, and add the repetition
+               // 4) check if displacement is ok, and add the repetition
                if(displacementOk(concentricFlag, yList[sampleStart], yList[sampleEnd]))
                        addRepetition(yList, sampleStart, sampleEnd);
        }
 
+       /*
+        * this finds local extreme on concentric at the beginning of the "real" phase
+        * data comes in Abs
+        * if eccentric: yList comes reversed (left - right)
+        */
+       private int findLocalExtreme(List<double> yList, int sampleStart, int sampleEnd, double maxAbs)
+       {
+               LogB.Information(string.Format("findLocalExtreme params: yList.Count: {0}, sampleStart: {1}, 
sampleEnd: {2}, maxAbs: {3}",
+                               yList.Count, sampleStart, sampleEnd, maxAbs));
+
+               int i = sampleStart;
+               //threshold for "non-force" segment at 5% of max
+               while(Math.Abs(yList[i]) < .05 * maxAbs && i < sampleEnd)
+                       i ++;
+
+               //find the lowest value at 70% end of the "non-force" segment
+               int startAt = Convert.ToInt32(sampleStart + (.7 * (i - sampleStart)));
+               int minLocalPos = startAt;
+               double minLocal = yList[startAt];
+
+               for(int j = startAt; j <= i; j ++)
+               {
+                       if(yList[j] < minLocal) {
+                               minLocal = yList[j];
+                               minLocalPos = j;
+                       }
+               }
+               return minLocalPos;
+       }
+
        private bool displacementOk (int concentricFlag, double sampleStart, double sampleEnd)
        {
                if ( ( concentricFlag == 1 && Math.Abs(sampleStart - sampleEnd) >= conMinDisplacement) ||