def read_popmap(filename):
	"""
	Read a population map file.
	Input:
		filename: file should be two-columns, tab-separated. IndIDs\tPopIDs. No header.
	Returns:
		results: dict of {indIDs: popIDs}
	"""
	results = dict()
	with open(filename, "r") as popfile:
		for line in popfile:
			line = line.strip()
			inds, pops = line.split()
			results[inds] = pops
	return results