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  1. import math, random, pylab
  2.  
  3. class Location(object):
  4.   def __init__(self, x, y):
  5.     self.x = float(x)
  6.     self.y = float(y)
  7.  
  8.   def move(self, xc, yc):
  9.     return Location(self.x+float(xc), self.y+float(yc))
  10.  
  11.   def getCoords(self):
  12.     return self.x, self.y
  13.  
  14.   def getDist(self, other):
  15.     ox, oy = other.getCoords()
  16.     xDist = self.x - ox
  17.     yDist = self.y - oy
  18.     return math.sqrt(xDist**2 + yDist**2)
  19.  
  20.  
  21. class CompassPt(object):
  22.   possibles = ('N', 'S', 'E', 'W')
  23.  
  24.   def __init__(self, pt):
  25.     if pt in self.possibles: self.pt = pt
  26.     else: raise ValueError('in CompassPt.__init__')
  27.  
  28.   def move(self, dist):
  29.     if self.pt == 'N': return (0, dist)
  30.     elif self.pt == 'S': return (0, -dist)
  31.     elif self.pt == 'E': return (dist, 0)
  32.     elif self.pt == 'W': return (-dist, 0)
  33.     else: raise ValueError('in CompassPt.move')
  34.  
  35.  
  36. class Field(object):
  37.  
  38.   def __init__(self, drunk, loc):
  39.     self.drunk = drunk
  40.     self.loc = loc
  41.  
  42.   def move(self, cp, dist):
  43.     oldLoc = self.loc
  44.     xc, yc = cp.move(dist)
  45.     self.loc = oldLoc.move(xc, yc)
  46.  
  47.   def getLoc(self):
  48.     return self.loc
  49.  
  50.   def getDrunk(self):
  51.     return self.drunk
  52.  
  53. class Drunk(object):
  54.   def __init__(self, name):
  55.     self.name = name
  56.  
  57.   def move(self, field, time = 1):
  58.     if field.getDrunk() != self:
  59.       raise ValueError('Drunk.move called with drunk not in field')
  60.     for i in range(time):
  61.       pt = CompassPt(random.choice(CompassPt.possibles))
  62.       field.move(pt, 1)
  63.  
  64. def performTrial(time, f):
  65.   start = f.getLoc()
  66.   distances = [0.0]
  67.   for t in range(1, time + 1):
  68.     f.getDrunk().move(f)
  69.     newLoc = f.getLoc()
  70.     distance = newLoc.getDist(start)
  71.     distances.append(distance)
  72.   return distances
  73.  
  74. drunk = Drunk('Homer Simpson')
  75.  
  76. for i in range(3):
  77.   f = Field(drunk, Location(0, 0))
  78.   distances = performTrial(500, f)
  79.   pylab.plot(distances)
  80.  
  81. pylab.title('Homer\'s Random Walk')
  82. pylab.xlabel('Time')
  83. pylab.ylabel('Distance from Origin')
  84.  
  85. def performSim(time, numTrials):
  86.   distLists = []
  87.   for trial in range(numTrials):
  88.     d = Drunk('Drunk' + str(trial))
  89.     f = Field(d, Location(0, 0))
  90.     distances = performTrial(time, f)
  91.     distLists.append(distances)
  92.   return distLists
  93.  
  94. def ansQuest(maxTime, numTrials):
  95.   means = []
  96.   distLists = performSim(maxTime, numTrials)
  97.   for t in range(maxTime + 1):
  98.     tot = 0.0
  99.     for distL in distLists:
  100.       tot += distL[t]
  101.     means.append(tot/len(distLists))
  102.   pylab.figure()
  103.   pylab.plot(means)
  104.   pylab.ylabel('distance')
  105.   pylab.xlabel('time')
  106.   pylab.title('Average Distance vs. Time (' + str(len(distLists)) + ' trials)')
  107.  
  108. ansQuest(500, 300)
  109. pylab.show()
  110.  
Runtime error #stdin #stdout #stderr 0.09s 11040KB
comments (?)
stdin 
Standard input is empty
stdout 
Standard output is empty
stderr 
Traceback (most recent call last):
  File "prog.py", line 1, in <module>
    import math, random, pylab
ImportError: No module named pylab
https://ideone.com/JBhjBx
language:
Python (cpython 2.7.16)
created:
10 years ago
visibility:
public

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