How to calculate given time average only

Curretly I am using below CDEF settings in my rrdcgi to show day time i.e. 7AM to 11 PM. Is there any setting to calculate the average of perticular time period only. I need to show the 7 day graphs so the average should be of 7 day, day time (7AM to 11 PM) only.

<h3>7 Day Performance</h3>
<RRD::GRAPH
        <RRD::GETVAR PATH>/rrdimg/7dayperformance.png
        --title="Performance"
        -w 1048 -h 266
        --imginfo '<IMG SRC=<RRD::GETVAR PATH>/rrdimg/%s WIDTH=%lu HEIGHT=%lu >'
        DEF:p1=<RRD::GETVAR PATH>/data1.rrd:data:AVERAGE
        DEF:p2=<RRD::GETVAR PATH>/data2.rrd:data:AVERAGE
        CDEF:p=p1,p2,2,AVG

        CDEF:gate=p1,POP,LTIME,86400,%,3600,/,FLOOR,DUP,23,LT,*,6,GT,INF,UNKN,IF   #for daytime image
        --end=midnight
        --start=end-7d
        AREA:gate#e0e0ff:"Day time"
        LINE2:p#ff6666:"performance"

EDIT

I am planning to filter out the logs from 7AM to 11PM and create new rrd files to create graphs. Is this a good approch. I dont think so because it will also include the null values.

Solution

When you use VDEF to calculate an average, it will build the average of the valid data, since you are already turning the non-office hours data to UNKN, all you have todo is to use VDEF and you should get what you are looking for.