The semantics for na.rm are different for aggregate than for the other options.
The former removes any rows that contain an NA prior to performing the
computation, the latter methods work column-wise. You have to decide which is
correct for your purposes.
---------------------------------------------------------------------------
Jeff Newmiller The ..... ..... Go Live...
DCN:<jdnew...@dcn.davis.ca.us> Basics: ##.#. ##.#. Live Go...
Live: OO#.. Dead: OO#.. Playing
Research Engineer (Solar/Batteries O.O#. #.O#. with
/Software/Embedded Controllers) .OO#. .OO#. rocks...1k
---------------------------------------------------------------------------
Sent from my phone. Please excuse my brevity.
Juliet Hannah <juliet.han...@gmail.com> wrote:
>I am calculating the mean of each column grouped by the variable 'id'.
>I do this using aggregate, data.table, and plyr. My aggregate results
>do not match the other two, and I am trying to figure out what is
>incorrect with my syntax. Any suggestions? Thanks.
>
>Here is the data.
>
>myData <- structure(list(var1 = c(31.59, 32.21, 31.78, 31.34, 31.61,
>31.61,
>30.59, 30.84, 30.98, 30.79, 30.79, 30.94, 31.08, 31.27, 31.11,
>30.42, 30.37, 30.29, 30.06, 30.3, 30.43, 30.61, 30.64, 30.75,
>30.39, 30.1, 30.25, 31.55, 31.96, 31.87, 30.29, 30.15, 30.37,
>29.59, 29.52, 28.96, 29.69, 29.58, 29.52, 30.21, 30.3, 30.25,
>30.23, 30.29, 30.39), var2 = c(33.78, 33.25, NA, 32.05, 32.59,
>NA, 32.24, NA, NA, 32.15, 32.39, NA, 32.4, 31.6, NA, 30.5, 30.66,
>NA, 30.6, 29.95, NA, 31.24, 30.73, NA, 30.51, 30.43, 31.17, 31.44,
>31.17, 31.18, 31.01, 30.98, 31.25, 30.44, 30.47, NA, 30.47, 30.56,
>NA, 30.6, 30.57, NA, 31, 30.8, NA), id = c("0m4", "0m4", "0m4",
>"0m5", "0m5", "0m5", "0m6", "0m6", "0m6", "0m11", "0m11", "0m11",
>"0m12", "0m12", "0m12", "205m1", "205m1", "205m1", "205m4", "205m4",
>"205m4", "205m5", "205m5", "205m5", "205m6", "205m6", "205m6",
>"205m7", "205m7", "205m7", "600m1", "600m1", "600m1", "600m3",
>"600m3", "600m3", "600m4", "600m4", "600m4", "600m5", "600m5",
>"600m5", "600m7", "600m7", "600m7")), .Names = c("var1", "var2",
>"id"), row.names = c(NA, -45L), class = "data.frame")
>
>> head(myData)
> var1 var2 id
>1 31.59 33.78 0m4
>2 32.21 33.25 0m4
>3 31.78 NA 0m4
>4 31.34 32.05 0m5
>5 31.61 32.59 0m5
>6 31.61 NA 0m5
>
>
>
>results1 <- aggregate(. ~ id ,data=myData,FUN=mean,na.rm=T)
> head(results1,1)
># id var1 var2
># 1 0m11 30.79 32.27
>
>library(data.table)
>mydt <- data.table(myData)
>setkey(mydt,id)
>results2 <- mydt[,lapply(.SD,mean,na.rm=TRUE),by=id]
> head(results2,1)
># id var1 var2
># [1,] 0m11 30.84 32.27
>
>library(plyr)
>results3 <- ddply(myData,.(id),colwise(mean),na.rm=TRUE)
> head(results3,1)
># id var1 var2
># 1 0m11 30.84 32.27
>
>> sessionInfo()
>R version 2.14.0 (2011-10-31)
>Platform: i386-pc-mingw32/i386 (32-bit)
>
>locale:
>[1] LC_COLLATE=English_United States.1252 LC_CTYPE=English_United
>States.1252 LC_MONETARY=English_United States.1252 LC_NUMERIC=C
>[5] LC_TIME=English_United States.1252
>
>attached base packages:
>[1] stats graphics grDevices utils datasets methods base
>
>other attached packages:
>[1] plyr_1.6 data.table_1.7.3
>
>______________________________________________
>R-help@r-project.org mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide
>http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
