Random walk code in python [2 dimensions] - python-2.7

Question

Please could you help me by figuring out what is the wrong with my code.
I am trying to write a program that generates random walks in two dimensions and that determines statistics about the position of the walker after 500 steps when the number of walks is 1000, the max step size is 0.9, and the separation between the two positions is 0.001.
import math
import random
import time
print "RANDOM WALKS ANALYSIS IN ONE DIMENSION"
NOFW_ = 1000 #The number of walks
NOFS_= 500 #The number of steps in each walk
MSS_ = 0.9 # The maximum step size[m]
SOFP_ = 0.001 # The separation of positions considered equal[m]
print " Number of walks: %3g"% NOFW_
print " Number of steps in each Walk: %3g"% NOFS_
print " Maximum step size: %3g"% MSS_,"m"
print "Separation of positions considered equal: %3g"% SOFP_,"m"
print
print "Please wait while random walks are generated and analyzed..."
print "Date:" + time.ctime()
print
def initialPosition():
return (0.0, 0.0)
def distance(posA, posB):
"""Calculates the distance between two positions posA and posB"""
distance = math.sqrt((posB[0] - posA[0])**2 + (posB[1] - posA[1])**2)
return distance
def printstats(description, numbers):
minimum_value_ = min(numbers)
numbers.sort()
Tenth_percentile = abs(0.10*len(numbers) + 0.5)
Mean_value_ = (1./float(len(numbers))*sum(numbers))
A = 0
for values in numbers:
B = distance(values, Mean_value_)
B = B**2
A = B + A
Standard_deviation = math.sqrt((1./(len(numbers)-1))*A)
Newposition_ = int(0.90*(len(numbers) + 0.5))
Ninetieth_percentile =numbers[Newposition_]
maximum_value_ = max(numbers)
print "Analysis for"""+ description
print "Minimum value: %9.1f" % minimum_value_
print "10th percentile: %7.1f" % Tenth_percentile
print "Mean value: %12.1f" % Mean_value_
print "Standard deviation: %4.1f" % Standard_deviation
print "90th percentile: %7.1f" % Ninetieth_percentile
print "Maximum value: %9.1f" % maximum_value_
list_1 = [minimum_value_, Tenth_percentile, Mean_value_, Standard_deviation, Ninetieth_percentile,maximum_value_]
return list_1
def takeStep(prevPosition, maxStep):
x = random.random()
y = random.random()
minStep = -maxStep
Z = random.random()*2*math.pi
stepsize_ = random.random()*0.9
Stepx= stepsize_*math.cos(Z)
Stepy= stepsize_*math.sin(Z)
New_positionx = prevPosition[0] + Stepx
New_positiony = prevPosition[1] + Stepy
return (New_positionx, New_positiony)
Step_100 = []
Step_500 = []
count_list = []
for walk in range(NOFW_):
Step1 = []
Position = (0.0,0.0)
count = 0
for step in range(NOFS_):
Next_Step_ = takeStep(Position, MSS_)
for word in Step1:
if distance(Next_Step_, word) <= SOFP_:
count +=1
position = Next_Step_
Step1.append(Next_Step_)
Step_100.append(Step1[-1])
Step_500.append(Step1[-1])
count_list.append(count)
Step_100 = printstats("distance from start at step 100 [m]", Step_100)
Step_500 = printstats("distance from start at step 500 [m]", Step_500)
count_list = printstats("times position revisited", count_list)

Answer 1

Your problem is here
Mean_value_ = (1./float(len(numbers))*sum(numbers))
sum() is supposed to get some numbers but your variable numbers is actually containing some tuples of 2 values
You may want to define your own sum function for tuples of 2 numbers, or to sum the first values and second values separately