position $=[$x$/2,$ y$/2]$

for t in range$($time$)$:

u $=$ np$.$random.uniform$()$

if u $<0\mathrm{.}25$:

position$[0]-=$ speed

elif u $<0\mathrm{.}5$:

position$[0]+=$ speed

elif u $<0\mathrm{.}75$:

position$[1]+=$ speed

else:

position$[1]-=$ speed

# check if ant has hit a wall and repeat step if necessary