[R] replace NA's with row means for specific columns

[Jim Lemon]

Hi Zahra,
I can't think of an "apply" function that will do this, but:

Zdf<-read.table(text="ID  A1 A2 A3   B1 B2  B3   C1 C2  C3   C4
b      4     5      NA        2       NA      4         5      1        3
   NA
c      4     5      1          NA      3        4         5      1        3
     2
d     NA   5      1          1        NA      4         5      1        3
   2
e      4     5      4          5       NA      4          5      1        3
     2",
header=TRUE)

Zdf

replace_NAs<-function(x,group_lab=c("A","B","C")) {
 for(lab in group_lab) {
  indices<-grep(lab,names(x),fixed=TRUE)
  na_indices<-is.na(x[indices])
  if(any(indices))
   x[indices][na_indices]<-rowMeans(x[indices],na.rm=TRUE)
 }
 return(x)
}

for(row in 1:dim(Zdf)[1]) Zdf[row,]<-replace_NAs(Zdf[row,])

Zdf

Jim

On Tue, Nov 3, 2015 at 6:49 AM, Zahra via R-help <r-help at r-project.org>
wrote:

> Hi there,
>
> I am looking for some help replacing missing values in R with the row
> mean. This is survey data and I am trying to impute values for missing
> variables in each set of questions separately using the mean of the scores
> for the other questions within that set.
>
> I have a dataset that looks like this
>
> ID      A1    A2    A3          B1     B2     B3         C1   C2   C3    C4
> b        4       5      NA          2       NA      4          5      1
>     3      NA
> c        4       5      1            NA      3        4          5      1
>       3      2
> d       NA     5      1            1        NA      4          5      1
>     3      2
> e        4       5      4            5       NA      4           5      1
>       3      2
>
>
> I want to replace any NA's in columns A1:A3 with the row mean for those
> columns only. So for ID=b, I want the NA in A3[ID=b] to be (4+5)/2 which is
> the average of the values in A1 and A2 for that row.
> Same thing for columns B1:B3 - I want the NA in B2[ID=b] to be the mean of
> the values of B1 and B3 in row ID=b so that B2[ID=b] becomes 3 which is
> (2+4)/2. And same in C1:C4, I want C4[ID=b] to become (5+1+3)/3 which is
> the mean of C1:C3.
>
> Then I want to go to row ID=c and do the same thing and so on.
>
> Can anybody help me do this? I have tried using rowMeans and subsetting
> but can't figure out the right code to do it.
>
> Thanks so much.
> Zahra
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
>

	[[alternative HTML version deleted]]