[R] how to use "lapplyBy" function of "doBy" package

[Gabor Grothendieck]

Here are four ways:


# using lapplyBy - DF is already sorted by group
library(doBy)
f <- function(x) {
	x$traits[is.na(x$traits)] <- mean(x$traits, na.rm = TRUE)
	x
}
do.call(rbind, lapplyBy(~ group, DF, f))

# using by - same f as before
do.call(rbind, by(DF, DF$group, f))

# using ave - nondestructive
g <- function(x) {
	x[is.na(x)] <- mean(x, na.rm = TRUE)
	x
}
transform(DF, traits = ave(DF$traits, DF$group, FUN = g))

# using ave - same but modifies DF - same g as before
DF$traits <- ave(DF$traits, DF$group, FUN = mean.na)


On Mon, Jun 8, 2009 at 10:01 PM, Mao Jianfeng<jianfeng.mao at gmail.com> wrote:
> Dear Ruser's
>
> I want to substitute each "NA" by the group mean of which the "NA" is
> belonging to. For example, substitute the first record of traits "NA" by the
> mean of "BSPy01-10" in the dummy dataframe.
>
> I have ever tried to solve this problem by using doBy package. But, I
> failed. I ask for the advice on how to use "lapplyBy" function of "doBy"
> package.
>
> The commands used and the output I got are as followed:
>
> library(doBy)
> df<-orderBy(~group,data=df)   # succeeded
> f1<-function(x){m<-mean(x, na.ram=TRUE); x[is.na(x)]<-m; x} # succeeded
> datatraits<-lapplyBy(traits~group,data=df, FUN=f1(traits)) # failed
> errors: mean(x, na.ram = TRUE), can not find 'traits'.
>
> dummy dataframe:
>> df
>       group traits
> 1  BSPy01-10     NA
> 2  BSPy01-10    7.3
> 3  BSPy01-10    7.3
> 4  BSPy01-11    5.3
> 5  BSPy01-11    5.4
> 6  BSPy01-11    5.6
> 7  BSPy01-11     NA
> 8  BSPy01-11     NA
> 9  BSPy01-11    4.8
> 10 BSPy01-12    8.1
> 11 BSPy01-12    6.0
> 12 BSPy01-12    6.0
> 13 BSPy01-13    6.1
>
> Thanks in advance.
>
> Sincerely,
>
> Mao J-F
>
>        [[alternative HTML version deleted]]
>
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