runningavg

Keep a running calculation of the average value of a series

Returns New average value
Keys
  1. Key to store the current average
  2. Key to store the current count of values
Args
  1. Next value in the series

Description

This script can be used to keep a running average of a series of values, without needing to keep each of the individual values around.

Example

> evalsha 399fddde578fd9cb924edce746c783e8340d8251 2 score:avg score:count 80
"80"
> evalsha 399fddde578fd9cb924edce746c783e8340d8251 2 score:avg score:count 100
"90"
> evalsha 399fddde578fd9cb924edce746c783e8340d8251 2 score:avg score:count 75
"85"
> evalsha 399fddde578fd9cb924edce746c783e8340d8251 2 score:avg score:count 98
"88.25"
> evalsha 399fddde578fd9cb924edce746c783e8340d8251 2 score:avg score:count 98
"90.2"
> evalsha 399fddde578fd9cb924edce746c783e8340d8251 2 score:avg score:count 98
"91.5"
> get score:avg
"91.5"
> get score:count
"6"

Source

local currentval = tonumber(redis.call('get', KEYS[1])) or 0
local count = redis.call('incr', KEYS[2])

currentval = tostring(currentval * (count - 1)/count + (ARGV[1]/count))

redis.call('set', KEYS[1], currentval)
return currentval

SHA

399fddde578fd9cb924edce746c783e8340d8251

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Last updated 14 Aug 2014.

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