From 6f418a5a837939b132967bcdb3ff0ede6d899bd2 Mon Sep 17 00:00:00 2001 From: Mario Mulansky Date: Tue, 12 May 2015 18:45:03 +0200 Subject: +functions to obtain values of the pwc/pwl profile Added __call__ operators to PieceWiseConst and PieceWiseLin class for obtaining function values at certain points in time. --- pyspike/PieceWiseConstFunc.py | 22 ++++++++++++++++++++++ pyspike/PieceWiseLinFunc.py | 30 ++++++++++++++++++++++++++++++ test/test_function.py | 32 +++++++++++++++++++++++++++++++- 3 files changed, 83 insertions(+), 1 deletion(-) diff --git a/pyspike/PieceWiseConstFunc.py b/pyspike/PieceWiseConstFunc.py index 41998ef..cf64e58 100644 --- a/pyspike/PieceWiseConstFunc.py +++ b/pyspike/PieceWiseConstFunc.py @@ -26,6 +26,28 @@ class PieceWiseConstFunc(object): self.x = np.array(x) self.y = np.array(y) + def __call__(self, t): + """ Returns the function value for the given time t. If t is a list of + times, the corresponding list of values is returned. + + :param: time t, or list of times + :returns: function value(s) at that time(s). + """ + assert np.all(t >= self.x[0]) and np.all(t <= self.x[-1]), \ + "Invalid time: " + str(t) + + ind = np.searchsorted(self.x, t, side='right') + # correct the cases t == x[0], t == x[-1] + try: + 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 self.y[ind-1] + def copy(self): """ Returns a copy of itself diff --git a/pyspike/PieceWiseLinFunc.py b/pyspike/PieceWiseLinFunc.py index f2442be..b9787eb 100644 --- a/pyspike/PieceWiseLinFunc.py +++ b/pyspike/PieceWiseLinFunc.py @@ -29,6 +29,36 @@ class PieceWiseLinFunc: self.y1 = np.array(y1) self.y2 = np.array(y2) + def __call__(self, t): + """ Returns the function value for the given time t. If t is a list of + times, the corresponding list of values is returned. + + :param: time t, or list of times + :returns: function value(s) at that time(s). + """ + def intermediate_value(x0, x1, y0, y1, x): + """ computes the intermediate value of a linear function """ + return y0 + (y1-y0)*(x-x0)/(x1-x0) + + assert np.all(t >= self.x[0]) and np.all(t <= self.x[-1]), \ + "Invalid time: " + str(t) + + ind = np.searchsorted(self.x, t, side='right') + # correct the cases t == x[0], t == x[-1] + try: + 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) + def copy(self): """ Returns a copy of itself diff --git a/test/test_function.py b/test/test_function.py index d81b03a..c56a295 100644 --- a/test/test_function.py +++ b/test/test_function.py @@ -10,7 +10,8 @@ Distributed under the BSD License from __future__ import print_function import numpy as np from copy import copy -from numpy.testing import assert_almost_equal, assert_array_almost_equal +from numpy.testing import assert_equal, assert_almost_equal, \ + assert_array_equal, assert_array_almost_equal import pyspike as spk @@ -20,6 +21,17 @@ def test_pwc(): x = [0.0, 1.0, 2.0, 2.5, 4.0] y = [1.0, -0.5, 1.5, 0.75] f = spk.PieceWiseConstFunc(x, y) + + # function values + assert_equal(f(0.0), 1.0) + assert_equal(f(0.5), 1.0) + assert_equal(f(2.25), 1.5) + assert_equal(f(3.5), 0.75) + assert_equal(f(4.0), 0.75) + + assert_array_equal(f([0.0, 0.5, 2.25, 3.5, 4.0]), + [1.0, 1.0, 1.5, 0.75, 0.75]) + xp, yp = f.get_plottable_data() xp_expected = [0.0, 1.0, 1.0, 2.0, 2.0, 2.5, 2.5, 4.0] @@ -38,11 +50,17 @@ def test_pwc(): assert_almost_equal(a, (-0.5*1.0+0.5*1.5+1.0*0.75)/2.5, decimal=16) a = f.avrg([1.0, 4.0]) assert_almost_equal(a, (-0.5*1.0+0.5*1.5+1.5*0.75)/3.0, decimal=16) + a = f.avrg([0.0, 2.2]) + assert_almost_equal(a, (1.0*1.0-0.5*1.0+0.2*1.5)/2.2, decimal=15) # averaging over multiple intervals a = f.avrg([(0.5, 1.5), (1.5, 3.5)]) assert_almost_equal(a, (0.5-0.5+0.5*1.5+1.0*0.75)/3.0, decimal=16) + # averaging over multiple intervals + a = f.avrg([(0.5, 1.5), (2.2, 3.5)]) + assert_almost_equal(a, (0.5*1.0-0.5*0.5+0.3*1.5+1.0*0.75)/2.3, decimal=15) + def test_pwc_add(): # some random data @@ -105,6 +123,18 @@ def test_pwl(): y1 = [1.0, -0.5, 1.5, 0.75] y2 = [1.5, -0.4, 1.5, 0.25] f = spk.PieceWiseLinFunc(x, y1, y2) + + # function values + assert_equal(f(0.0), 1.0) + assert_equal(f(0.5), 1.25) + assert_equal(f(2.25), 1.5) + assert_equal(f(2.5), 0.75) + assert_equal(f(3.5), 0.75-0.5*1.0/1.5) + assert_equal(f(4.0), 0.25) + + assert_array_equal(f([0.0, 0.5, 2.25, 2.5, 3.5, 4.0]), + [1.0, 1.25, 1.5, 0.75, 0.75-0.5*1.0/1.5, 0.25]) + xp, yp = f.get_plottable_data() xp_expected = [0.0, 1.0, 1.0, 2.0, 2.0, 2.5, 2.5, 4.0] -- cgit v1.2.3