R help - May 2011 - Dealing with null values Aggregate function

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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Andy,


have a look at ?mean. The na.omit argument set to TRUE should solve your 
problem. The use in aggregate would be something like:

aggregate(x = testDF, by = list(testDF$v3), FUN = function(x)
mean(x,na.rm=TRUE))



HTH
Jannis



On 05/17/2011 04:27 AM, Andrew McFadden wrote:
> 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
>
>
>
>
>
> This email message and any attachment(s) is intended solely for the
addressee(s)
> named above. The information it contains is confidential and may be legally
> privileged.  Unauthorised use of the message, or the information it
contains,
> may be unlawful. If you have received this message by mistake please call
the
> sender immediately on 64 4 8940100 or notify us by return email and erase
the
> original message and attachments. Thank you.
>
> The Ministry of Agriculture and Forestry accepts no responsibility for
changes
> made to this email or to any attachments after transmission from the
office.
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
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