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comparison python/moving.py @ 250:59f547aebaac

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modified prediction functions, added norm/angle representation of Points
author Nicolas Saunier <nicolas.saunier@polymtl.ca>
date Mon, 23 Jul 2012 02:50:26 -0400
parents 99173da7afae
children 13ec22bec5d4
comparison
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249:99173da7afae 250:59f547aebaac
226 @staticmethod 226 @staticmethod
227 def plotAll(points, color='r'): 227 def plotAll(points, color='r'):
228 from matplotlib.pyplot import scatter 228 from matplotlib.pyplot import scatter
229 scatter([p.x for p in points],[p.y for p in points], c=color) 229 scatter([p.x for p in points],[p.y for p in points], c=color)
230 230
231 231 class NormAngle:
232 def predictPosition(nTimeSteps, initialPosition, initialVelocity, initialAcceleration = Point(0,0)): 232 'alternate encoding of a point, by its norm and orientation'
233
234 def __init__(self, norm, angle):
235 self.norm = norm
236 self.angle = angle
237
238 @staticmethod
239 def fromPoint(p):
240 from math import atan2
241 norm = p.norm2()
242 if norm > 0:
243 angle = atan2(p.x, p.y)
244 return NormAngle(norm, angle)
245
246 def __add__(self, other):
247 'a norm cannot become negative'
248 return NormAngle(max(self.norm+other.norm, 0), self.orientation+other.orientation)
249
250 def getPoint(self):
251 from math import cos, sin
252 return Point(self.norm*cos(self.orientation), self.norm*sin(self.orientation))
253
254
255 def predictPositionNoLimit(nTimeSteps, initialPosition, initialVelocity, initialAcceleration = Point(0,0)):
233 '''Predicts the position in nTimeSteps at constant speed/acceleration''' 256 '''Predicts the position in nTimeSteps at constant speed/acceleration'''
234 return initialPosition+initialVelocity.multiply(nTimeSteps) + initialAcceleration.multiply(nTimeSteps**2) 257 return initialVelocity + initialAcceleration.multiply(nTimeSteps),initialPosition+initialVelocity.multiply(nTimeSteps) + initialAcceleration.multiply(nTimeSteps**2*0.5)
258
259 def predictPosition(position, speedOrientation, control, maxSpeed = None):
260 '''Predicts the position (moving.Point) at the next time step with given control input (deltaSpeed, deltaTheta)
261 speedOrientation is the other encoding of velocity, (speed, orientation)
262 speedOrientation and control are NormAngle'''
263 predictedSpeedTheta = speedOrientation+control
264 if maxSpeed:
265 predictedSpeedTheta.norm = min(predictedSpeedTheta.norm, maxSpeed)
266 predictedPosition = position+predictedSpeedTheta.getPoint()
267 return predictedPosition, predictedSpeedTheta
235 268
236 269
237 class FlowVector: 270 class FlowVector:
238 '''Class to represent 4-D flow vectors, 271 '''Class to represent 4-D flow vectors,
239 ie a position and a velocity''' 272 ie a position and a velocity'''