What is hardy-weinberg equilibrium?

Hardy-Weinberg equilibrium in a concept that states that a population's genotype frequencies stay the same over time as long as certain conditions are met. There are five conditions needed for a population to stay in equilibrium. Populations that meet these conditions are not evolving. The conditions are that the population must be very large, so no genetic drift can occur; no emigration or immigration, so no gene flow can occur; no mutations can occur; mating must random, so no sexual selection can occur; and there must be no natural selection, with all traits equally aiding survival. However, all these conditions are rarely met by real populations.

Are you asking about a street map usage  if so here is your answer  a street map for a very limited area could simply be a bit map or a .jpg image.  but a more general map would probably store the streets as vectors.  but you shouldn't assume that there is one way to do it