#!/usr/bin/env bash
#
# calculates rolling average for numbers via stdin
#
# here's an example with hledger:
#
# hledger bal ^in cur:USD -MA --end=thismonth --output-format=csv \
#   | tail -n 1 \
#   | cut -d',' -f 2- \
#   | tr -d '" USD-' \
#   | tr ',' '\n' \
#   | rollingavg
n=0
total=0
declare -i n
while read i
do
    n+=1
    total=$(bc -l <<< "$total + $i")
    printf "%.2f\n"  $(bc -l <<< "$total / $n")
done