3d288d60d6
problems when trying to import files from the code subdirectory. I also tried to rearange some code so that book_format does not need to be imported if you are not running in a Jupyter Notebook.
74 lines
1.9 KiB
Python
74 lines
1.9 KiB
Python
# -*- coding: utf-8 -*-
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"""Copyright 2015 Roger R Labbe Jr.
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Code supporting the book
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Kalman and Bayesian Filters in Python
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https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
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This is licensed under an MIT license. See the LICENSE.txt file
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for more information.
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"""
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from __future__ import (absolute_import, division, print_function,
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unicode_literals)
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import copy
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import math
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import numpy as np
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from numpy.random import randn
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class DogSimulation(object):
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def __init__(self, x0=0, velocity=1,
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measurement_var=0.0, process_var=0.0):
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""" x0 - initial position
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velocity - (+=right, -=left)
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measurement_variance - variance in measurement m^2
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process_variance - variance in process (m/s)^2
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"""
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self.x = x0
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self.velocity = velocity
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self.measurement_noise = math.sqrt(measurement_var)
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self.process_noise = math.sqrt(process_var)
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def move(self, dt=1.0):
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'''Compute new position of the dog assuming `dt` seconds have
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passed since the last update.'''
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# compute new position based on velocity. Add in some
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# process noise
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velocity = self.velocity + randn() * self.process_noise * dt
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self.x += velocity * dt
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def sense_position(self):
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# simulate measuring the position with noise
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return self.x + randn() * self.measurement_noise
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def move_and_sense(self, dt=1.0):
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self.move(dt)
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x = copy.deepcopy(self.x)
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return x, self.sense_position()
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def run_simulation(self, dt=1, count=1):
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""" simulate the dog moving over a period of time.
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**Returns**
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data : np.array[float, float]
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2D array, first column contains actual position of dog,
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second column contains the measurement of that position
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"""
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return np.array([self.move_and_sense(dt) for i in range(count)])
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