wafer.py

import csv

with open('wafer.csv', 'r') as f:
	reader = csv.reader(f, delimiter=',')
	wafer = [row for row in reader]

wafer_set = set([i[1] for i in wafer])

result = []
for n in wafer_set:
	result.append([	0, \
			int(n), \
			sum([int(i[2]) for i in wafer if i[1] == n and str(i[2]) != '-']), \
			sum([1 for i in wafer if i[1] == n and str(i[2]) != '-'])\
			])

print result