[rrd-users] Re: percentile calculations

[Ralf Kruedewagen]

Hi,

just a comment about how I get the percentiles from my RRDtool data:

Cacti (a RRDtool GUI) has a variable "Nth Percentile", see
http://cacti.net/downloads/docs/html/variables.html. 

Cacti does not use the built-in RRDtool function. UNKOWN values are ignored 
and the result is as you would expect. Nth can be any number between 1 and 
99.

Cheers
Ralf


On Tuesday 05 September 2006 20:01, Dan Cech wrote:
> Hello All,
>
> I have a question regarding calculating percentiles.
>
> Specifically, I have a graph showing data over which I need to overlay a
> 95th percentile line.
>
> However, when I'm displaying the graph for the current month, the
> PERCENT function is using all the unknown future values in the
> calculation, causing it to be incorrect.
>
> As a very simplified example, say I'm 10 days into a month (with 20 days
> remaining) and the values so far look like this:
>
> 1,2,3,4,5,6,7,8,9,10
>
> The 90th percentile should be 9, but in fact it will be 7 because
> PERCENT will use the 20 NaN values in the calculation.
>
> I have looked through the documentation and can't find any mechanism
> which would allow me to restrict the PERCENT function to a specific date
> range (to exclude values in the future), or exclude NaN values.
>
> Any suggestions would be appreciated.
>
> Thanks,
>
> Dan
>
> --
> Unsubscribe mailto:rrd-users-request at list.ee.ethz.ch?subject=unsubscribe
> Help        mailto:rrd-users-request at list.ee.ethz.ch?subject=help
> Archive     http://lists.ee.ethz.ch/rrd-users
> WebAdmin    http://lists.ee.ethz.ch/lsg2.cgi

--
Unsubscribe mailto:rrd-users-request at list.ee.ethz.ch?subject=unsubscribe
Help        mailto:rrd-users-request at list.ee.ethz.ch?subject=help
Archive     http://lists.ee.ethz.ch/rrd-users
WebAdmin    http://lists.ee.ethz.ch/lsg2.cgi