From a61a14295e28e6e95fa510693a11ae8c78a552ab Mon Sep 17 00:00:00 2001
From: Mario Mulansky <mario.mulansky@gmx.net>
Date: Sun, 17 May 2015 17:50:39 +0200
Subject: return correct values at exact spike times

pwc and pwl function object return the average of the left and right limit
as function value at the exact spike times.
---
 pyspike/PieceWiseLinFunc.py | 51 ++++++++++++++++++++++++++++++++++-----------
 1 file changed, 39 insertions(+), 12 deletions(-)

(limited to 'pyspike/PieceWiseLinFunc.py')

diff --git a/pyspike/PieceWiseLinFunc.py b/pyspike/PieceWiseLinFunc.py
index b9787eb..03c2da2 100644
--- a/pyspike/PieceWiseLinFunc.py
+++ b/pyspike/PieceWiseLinFunc.py
@@ -44,20 +44,47 @@ class PieceWiseLinFunc:
             "Invalid time: " + str(t)
 
         ind = np.searchsorted(self.x, t, side='right')
-        # correct the cases t == x[0], t == x[-1]
-        try:
+        if isinstance(t, collections.Sequence):
+            # t is a sequence of values
+            # correct the cases t == x[0], t == x[-1]
             ind[ind == 0] = 1
             ind[ind == len(self.x)] = len(self.x)-1
-        except TypeError:
-            if ind == 0:
-                ind = 1
-            if ind == len(self.x):
-                ind = len(self.x)-1
-        return intermediate_value(self.x[ind-1],
-                                  self.x[ind],
-                                  self.y1[ind-1],
-                                  self.y2[ind-1],
-                                  t)
+            value = intermediate_value(self.x[ind-1],
+                                       self.x[ind],
+                                       self.y1[ind-1],
+                                       self.y2[ind-1],
+                                       t)
+            # correct the values at exact spike times: there the value should
+            # be the at half of the step
+            # obtain the 'left' side indices for t
+            ind_l = np.searchsorted(self.x, t, side='left')
+            # if left and right side indices differ, the time t has to appear
+            # in self.x
+            ind_at_spike = np.logical_and(np.logical_and(ind != ind_l,
+                                                         ind > 1),
+                                          ind < len(self.x))
+            # get the corresponding indices for the resulting value array
+            val_ind = np.arange(len(ind))[ind_at_spike]
+            # and for the values in self.x, y1, y2
+            xy_ind = ind[ind_at_spike]
+            # the values are defined as the average of the left and right limit
+            value[val_ind] = 0.5 * (self.y1[xy_ind-1] + self.y2[xy_ind-2])
+            return value
+        else:  # t is a single value
+            # specific check for interval edges
+            if t == self.x[0]:
+                return self.y1[0]
+            if t == self.x[-1]:
+                return self.y2[-1]
+            # check if we are on any other exact spike time
+            if sum(self.x == t) > 0:
+                # use the middle of the left and right Spike value
+                return 0.5 * (self.y1[ind-1] + self.y2[ind-2])
+            return intermediate_value(self.x[ind-1],
+                                      self.x[ind],
+                                      self.y1[ind-1],
+                                      self.y2[ind-1],
+                                      t)
 
     def copy(self):
         """ Returns a copy of itself
-- 
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