added missing py files

1 files changed, 168 insertions, 0 deletions

diff --git a/pyspike/PieceWiseConstFunc.py b/pyspike/PieceWiseConstFunc.py
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+"""
+Class representing piece-wise constant functions.
+
+Copyright 2014-2015, Mario Mulansky <mario.mulansky@gmx.net>
+
+Distributed under the BSD License
+
+"""
+from __future__ import print_function
+
+import numpy as np
+import collections
+
+
+##############################################################
+# PieceWiseConstFunc
+##############################################################
+class PieceWiseConstFunc(object):
+    """ A class representing a piece-wise constant function. """
+
+    def __init__(self, x, y):
+        """ Constructs the piece-wise const function.
+
+        :param x: array of length N+1 defining the edges of the intervals of
+                  the pwc function.
+        :param y: array of length N defining the function values at the
+                  intervals.
+        """
+        # convert parameters to arrays, also ensures copying
+        self.x = np.array(x)
+        self.y = np.array(y)
+
+    def copy(self):
+        """ Returns a copy of itself
+
+        :rtype: :class:`PieceWiseConstFunc`
+        """
+        return PieceWiseConstFunc(self.x, self.y)
+
+    def almost_equal(self, other, decimal=14):
+        """ Checks if the function is equal to another function up to `decimal`
+        precision.
+
+        :param other: another :class:`PieceWiseConstFunc`
+        :returns: True if the two functions are equal up to `decimal` decimals,
+                  False otherwise
+        :rtype: bool
+        """
+        eps = 10.0**(-decimal)
+        return np.allclose(self.x, other.x, atol=eps, rtol=0.0) and \
+            np.allclose(self.y, other.y, atol=eps, rtol=0.0)
+
+    def get_plottable_data(self):
+        """ Returns two arrays containing x- and y-coordinates for immeditate
+        plotting of the piece-wise function.
+
+        :returns: (x_plot, y_plot) containing plottable data
+        :rtype: pair of np.array
+
+        Example::
+
+            x, y = f.get_plottable_data()
+            plt.plot(x, y, '-o', label="Piece-wise const 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 integral(self, interval=None):
+        """ Returns the integral over the given interval.
+
+        :param interval: integration interval given as a pair of floats, if
+                         None the integral over the whole function is computed.
+        :type interval: Pair of floats or None.
+        :returns: the integral
+        :rtype: float
+        """
+        if interval is None:
+            # no interval given, integrate over the whole spike train
+            a = np.sum((self.x[1:]-self.x[:-1]) * self.y)
+        else:
+            # find the indices corresponding to the interval
+            start_ind = np.searchsorted(self.x, interval[0], side='right')
+            end_ind = np.searchsorted(self.x, interval[1], side='left')-1
+            assert start_ind > 0 and end_ind < len(self.x), \
+                "Invalid averaging interval"
+            # first the contribution from between the indices
+            a = np.sum((self.x[start_ind+1:end_ind+1] -
+                        self.x[start_ind:end_ind]) *
+                       self.y[start_ind:end_ind])
+            # correction from start to first index
+            a += (self.x[start_ind]-interval[0]) * self.y[start_ind-1]
+            # correction from last index to end
+            a += (interval[1]-self.x[end_ind]) * self.y[end_ind]
+        return a
+
+    def avrg(self, interval=None):
+        """ Computes the average of the piece-wise const function:
+        :math:`a = 1/T int_0^T f(x) dx` where T is the length of the interval.
+
+        :param interval: averaging interval given as a pair of floats, a
+                         sequence of pairs for averaging multiple intervals, or
+                         None, if None the average over the whole function is
+                         computed.
+        :type interval: Pair, sequence of pairs, or None.
+        :returns: the average a.
+        :rtype: float
+        """
+        if interval is None:
+            # no interval given, average over the whole spike train
+            return self.integral() / (self.x[-1]-self.x[0])
+
+        # check if interval is as sequence
+        assert isinstance(interval, collections.Sequence), \
+            "Invalid value for `interval`. None, Sequence or Tuple expected."
+        # check if interval is a sequence of intervals
+        if not isinstance(interval[0], collections.Sequence):
+            # just one interval
+            a = self.integral(interval) / (interval[1]-interval[0])
+        else:
+            # several intervals
+            a = 0.0
+            int_length = 0.0
+            for ival in interval:
+                a += self.integral(ival)
+                int_length += ival[1] - ival[0]
+            a /= int_length
+        return a
+
+    def add(self, f):
+        """ Adds another PieceWiseConst function to this function.
+        Note: only functions defined on the same interval can be summed.
+
+        :param f: :class:`PieceWiseConstFunc` function to be added.
+        :rtype: None
+        """
+        assert self.x[0] == f.x[0], "The functions have different intervals"
+        assert self.x[-1] == f.x[-1], "The functions have different intervals"
+
+        # cython version
+        try:
+            from cython_add import add_piece_wise_const_cython as \
+                add_piece_wise_const_impl
+        except ImportError:
+            print("Warning: add_piece_wise_const_cython not found. Make sure \
+that PySpike is installed by running\n 'python setup.py build_ext --inplace'! \
+\n Falling back to slow python backend.")
+            # use python backend
+            from python_backend import add_piece_wise_const_python as \
+                add_piece_wise_const_impl
+
+        self.x, self.y = add_piece_wise_const_impl(self.x, self.y, f.x, f.y)
+
+    def mul_scalar(self, fac):
+        """ Multiplies the function with a scalar value
+
+        :param fac: Value to multiply
+        :type fac: double
+        :rtype: None
+        """
+        self.y *= fac