CODEWITHSUNDEEP
pythonrandom
SRQ
SRQ

Reputation: 7

Simple random walk

I am having trouble producing a simple random walk path similar to what I use in my spreadsheets. How do I write the code so that each step is added to the previous step in order to keep a "running total" that would show distance from zero? Starting at zero, plus one step, plus one step, minus one step would equal +1 (0+1+1-1). Using random selection of course.

Also, is there a way to plot a chart of this with Python3.4?

import random

a = 0

trials = input('Trails : ')

while a < int(trials):

    a = a + 1                  # Simple step counter
    x = random.randint(-1,1)   # Step direction (-1, 0, +1)

    print(a,x)                 # Prints numbered list of steps and direction

Upvotes: 0

Views: 995

Answers (2)

Michael H.
Michael H.

Reputation: 3483

The position as a function of number of random steps made can be calculated with np.cumsum(np.random.randint(-1,2,10)). You can plot it as a function of number of steps with

import numpy as np
import matplotlib.pyplot as plt

increment = np.random.randint(-1,2,10)
position = np.cumsum(increment)
plt.plot(np.arange(1, position.shape[0]+1), position)
plt.show()

Upvotes: 0

Tony Suffolk 66
Tony Suffolk 66

Reputation: 9704

This should do it (i.e. keep a running total) - as for plotting - you might need to keep the total for each step in a list and use another library - such as matplotlib, to plot the results. 

import random

a = 0
total = 0 # Keep track of the total 

trials = input('Trails : ')

while a < int(trials):

    a = a + 1                  # Simple step counter
    x = random.randint(-1,1)   # Step direction (-1, 0, +1)
    total += x                 # Add this step to the total

    print(a,x, total)          # Prints numbered list of steps and direction

Upvotes: 2

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