Handy script for calculating averages streamed via stdin

runningavg.py

#!/usr/bin/env python
import sys

CHUNK = 100

if len(sys.argv) > 1:
    CHUNK = int(sys.argv[1])

vals = []
i = 1
while 1:
    l = sys.stdin.readline()
    if not l:
        break
    vals.append(float(l.strip()))
    if i % CHUNK == 0:
        s = sum(vals)
        print "Count: %10d - Total: %10.4f - Average: %10.4f" % (
            len(vals), s, s / len(vals))
    i += 1

s = sum(vals)
print "Count: %10d - Total: %10.4f - Average: %10.4f" % (i+1, s, s / i+1)