histogram

# fields		=	ordered list of sorting fields
# obs			=	an iterator of objects where fields are present (fields MUST exist)
# order_desc	=	Sort descending(false)
# ignore_case	=	put field vales to lowercase, generates less overlap
# top_count		=	return the top X
def histo(fields, obs, order_desc=True, ignore_case=False, top_count=None):

	master = []

	if not type(fields) == list:
		fields = [fields]

	for o in obs:
		tmp = ()
		for f in fields:

			if ignore_case:
				val = str(getattr(o, f)).strip().lower()
			else:
				val = str(getattr(o, f)).strip()

			tmp = tmp + (val,)

		master.append(tmp)

	master = Counter(master)
	master_counted = master.most_common(top_count)

	# master_ordered = sorted(master.items(), key=lambda i: i[1], reverse=order_desc)

	max_width = max(len(', '.join(i[0])) for i in master_counted)
	max_count = sum(master.values())

	print "%s %s %s %s" % ('Fields'.ljust(max_width), 'Count', 'Percent', 'Hist')

	for line in master_counted:
		left = ', '.join(line[0])

		count = line[1]

		raw_percent = (100.0 * count/max_count)
		padded_percent = "{:.2f}".format(raw_percent)

		hist_line = int(raw_percent) * u'\u25A0'

		print "%s %s %s%% %s" % (left.ljust(max_width), str(count).ljust(min(5,master_counted[0])), str(padded_percent).rjust(6), hist_line)