Thank you all for your help! I figured out a way with the help of the above answer!:
Step=random('uniform',0,1,1,2*(samples/run));
%% Defining directions
% for each step, if, 0<step<0.1,turn left;
% 0.1<step<0.2,turn right;
% step>0.2, go straight;
%% 7 outcomes
thus calculating the mean and variance through expectation!