Revise the code of randomWalkPoints to have the entity go with equal probability

Question

Revise the code of randomWalkPoints to have the entity go with equal probability in a N, S, E, or W direction. Hint: Choose the direction based on the value of a random integer, 0, 1, 2, or 3.

function [lst] = randomWalkPoints(n)
% RANDOMWALKPOINTS Function to produce a random walk, where at each time
% step the entity goes diagonally in a NE, NW, SE, or SW direction, and to
% return a list of the points in the walk
% Pre:   n is the number of steps in the walk.
% Post:   A list of the points in the walk has been returned.
x = 0;
y = 0;
lst = zeros(n + 1,2);
lst(1, :) = [0 0];
for i = 1:n
    if randi([0,1]) == 0
        x = x + 1;
    else
        x = x - 1;
    end;
    if randi([0,1]) == 0
        y = y + 1;
    else
        y = y - 1;
    end;
    lst(i + 1, :) = [x y];
end;   

itled03.m ×| stepwi se.m X| graphs 1.m ×1 monteCarloproject3.m randomwalkPoints.m X1 + function [1st] = randomwalkPoints(n) % RANDOMWALKPOINTS Function to produce a random walk, where at each time step the entity goes diagonally in a NE, NW, SE, or SW direction, and to % return a list of the points in the walk Pre: n is the number of steps in the walk. % Post: A list of the points in the walk has been returned. x=0 y=0 lst = zeros(n + 1,2); 1st(1, :) = [0 0]; for i 1:n if rand 1( [0,1]) = 0 x = x + 1; else x=x-1; end; if rand 1( [0,1]) = 0 y=y+1; else y=y-1; 1st(i + 1, :) = [x y]; end;

Explanation / Answer

***********************PLEASE FIND INLINE COMMENTS FOR CODE EXPLANATION**********************************

function [lst] = randomWalkPoints(n)
% RANDOMWALKPOINTS Function to produce a random walk, where at each time
% step the entity goes in N, E, W or S direction, and to
% return a list of the points in the walk
% Pre: n is the number of steps in the walk.
% Post: A list of the points in the walk has been returned.

% Here x represents the x coordinate of a point and y represents the y
% coorinate. Since, we assume that the random walk is always started from origin,
% lets assign x = 0 and y = 0
x = 0;
y = 0;

% Since n steps from origin results in n + 1 points, lets create a vector
% 'lst' with 'n + 1' rows and 2 columns.
% This vector is used for storing x and y values of n + 1 points.
lst = zeros(n + 1,2);

% firstt point is always origin, hence, initialize first row to (0, 0).
lst(1, :) = [0 0];

% run a loop for n steps. Here i+1 represents the row number.
for i = 1:n

% now, lets pick a random integer between 1, 2, 3 or 4
% where 1 means go North, 2 means go South, 3 means go East,
% 4 means go West.
randNumber = randi(4);
  
% If randNumber is 1, we need to go North, hence, increment y by 1
if randNumber == 1
y = y + 1;

% If randNumber is 2, we need to go South, hence, decrement y by 1
elseif randNumber == 2
y = y - 1;
  
% If randNumber is 3, we need to go Ease, hence, increment x by 1
elseif randNumber == 3
x = x + 1;
  
% Else randNumber is 4, we need to go West, hence, decrement x by 1
else
x = x - 1;
  
% Now copy the values of x and y to the (i+1)th row in lst
lst(i + 1, :) = [x y];
end;

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