isi distance and basic example

1 files changed, 60 insertions, 0 deletions

diff --git a/pyspike/function.py b/pyspike/function.py
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+""" function.py
+
+Module containing classes representing piece-wise constant and piece-wise linear
+functions.
+
+Copyright 2014, Mario Mulansky <mario.mulansky@gmx.net>
+
+"""
+from __future__ import print_function
+
+import numpy as np
+
+class PieceWiseConstFunc:
+    """ A class representing a piece-wise constant function. """
+    
+    def __init__(self, x, y):
+        """ Constructs the piece-wise const function.
+        Params:
+        - x: array of length N+1 defining the edges of the intervals of the pwc
+        function.
+        - y: array of length N defining the function values at the intervals.
+        """
+        self.x = x
+        self.y = y
+
+    def get_plottable_data(self):
+        """ Returns two arrays containing x- and y-coordinates for immeditate
+        plotting of the piece-wise function.
+        """
+
+        x_plot = np.empty(2*len(self.x)-2)
+        x_plot[0] = self.x[0]
+        x_plot[1::2] = self.x[1:]
+        x_plot[2::2] = self.x[1:-1]
+        y_plot = np.empty(2*len(self.y))
+        y_plot[::2] = self.y
+        y_plot[1::2] = self.y
+
+        return x_plot, y_plot
+
+    def avrg(self):
+        """ Computes the average of the piece-wise const function:
+        a = 1/T int f(x) dx where T is the length of the interval.
+        Returns:
+        - the average a. 
+        """
+        print(self.x)
+        print(self.y)
+        return np.sum((self.x[1:]-self.x[:-1]) * self.y) / \
+            (self.x[-1]-self.x[0])
+
+    def abs_avrg(self):
+        """ Computes the average of the abs value of the piece-wise const 
+        function:
+        a = 1/T int |f(x)| dx where T is the length of the interval.
+        Returns:
+        - the average a. 
+        """
+        return np.sum((self.x[1:]-self.x[:-1]) * np.abs(self.y)) / \
+            (self.x[-1]-self.x[0])