When computing statistics on each base across a chromosome, it is often not feasible to put the whole chromosome into memory.
Here is a python generator function to create segments on a chromosome and iterate through them.
def make_regions(chromosome_length, how_many_bases_to_look_at):
start = 0
end = start + how_many_bases_to_look_at
while end < chromosome_length:
yield (start, end)
start = end
end = end + how_man_bases_to_look_at
yield (start, chromosome_length)
