Alex van den Bogaerdt wrote: > On Sun, Dec 01, 2002 at 01:38:46AM +0100, Luc Moreau wrote: > > >>I'm new to this list. I'm trying to investigate ways of averaging >>variables by time of day (over a sequence of days) or even day of week
To make my request even more clear (I hope), what I'm interested in is a moving average of this variable by time of day and day of week. This Monday's 10am value should be computed (for instance) as 10% of the new value of that variable + 90% of last Monday 10am (unless the latter is unknown, in which case I could take 100% of the new value). >>(averaging all Mondays at 10am). Is there support for this in RRD ? As >>far as I can see, I can record the raw data with RRD but the kind of >>averaging I want to do, it seems I'll have to do it by external >>programs. Did I miss something obvious ? > As far as I know, averaging will discard NaN values. This means you > can create a CDEF that, for instance, only "passes through" data from > 10:00 to 11:00 and average this. > > Create 24 of such CDEFs and you have an hourly distribution. I tried your method with some success; > > Example CDEF: > > CDEF:hour11=input,LTIME,86400,%,39601,43200,LIMIT,UN,UNKN,input,IF I think you don't need the first reference to "input" in the above CDEF. It will be left back on the stack and RRD detects that the stack depth is > 1 with the CDEF as written. But that's a detail. I tested with: CDEF:hour11=LTIME,86400,%,39601,43200,LIMIT,UN,UNKN,delta,IF where delta is a variable from my RRD. > > How does this work: ... skipped CDEF explanation ... > Now show the average of hour11 and you should get what you asked for. This perfectly shows the value (or average value, depending on the --step used) filtered with the time window in the CDEF. I tried with --step 3600 and this gives a neat average between 11:00 and 12:00 each day. But if I try to increase the --step, at about 7200 there is nothing displayed on the graph. I think that's because I specified a 0.5 "xfiles factor" when creating the RRD, and a step of 2 hours when there is only data for 1 hour leads to... only 50% valid data. How do I go about averaging this "hour11" over more than 1 day then ? Anyway, thanks Alex for your help with this. I'll go on tinkering more rrdtool options. Maybe recreate the RRD with a very low xfiles factor will help... Luc -- Luc Moreau (lucm at advalvas dot be) Linux (because reboots are for upgrades ;-) -- Unsubscribe mailto:[EMAIL PROTECTED] Help mailto:[EMAIL PROTECTED] Archive http://www.ee.ethz.ch/~slist/rrd-users WebAdmin http://www.ee.ethz.ch/~slist/lsg2.cgi
