Hi R users

I trying to some aggregate statistics on a very large dataset. The null
values are causing a problem. I would like to calculate aggregate values
for groups. I am just no sure how to deal with the "" I would ideally
like them to ignored ie if there is only 1 value over several columns
than that value would be the summary statistic.

I have put the following example together to show my problem.

testDF <- data.frame(v1 = c(1,3,5,7,8,3,5,NA,4,5,7,9),
                     v2 = c(11,33,55,77,88,33,55,NA,44,55,77,99),
	
v3=c("red","red","red","red","red","red","blue","blue","blue","blue","bl
ue","blue"))

aggregate(x = testDF, by = list(testDF$v3), FUN = "mean")

For this example I would like to get a mean value for red (v1=4.5; v1=5)
and blue (v1=49.5; v2=55)

Thank you in advance.

Andy

Andrew McFadden MVS BVSc
Incursion Investigator
Investigation & Diagnostic Centres - Wallaceville Biosecurity New 
Zealand Ministry of Agriculture and Forestry

Phone 04 894 5600 Fax 04 894 4973 Mobile 029 894 5611 Postal address: 
Investigation and Diagnostic Centre- Wallaceville Box 40742 Ward St 
Upper Hutt





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