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[Question #219778]: Problem computing weighted average

To: graphite-dev@xxxxxxxxxxxxxxxxxxx
From: Matt Thomson <question219778@xxxxxxxxxxxxxxxxxxxxx>
Date: Mon, 21 Jan 2013 20:31:03 -0000
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New question #219778 on Graphite:
https://answers.launchpad.net/graphite/+question/219778

I'm trying to show a graph of a weighted average of some series in Graphite.  

I have a number of series of response times from various servers, together with the numbers of requests to each servers (which are the weights).  I'd like to compute:

avg = ((weight1 * value1) + (weight2 * value2)) / (weight1 + weight2)

However, I'm having trouble calculating this expression.  I've separated out various parts, and found that, if I put in the target:

sumSeries(multiplySeries(series1,weights1))

then Graphite just displays "No data".  If I switch around the sum and multiply, then Graphite displays the data just fine.

What could I be doing wrong?

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