[R] substitute NA values

[Jim Lemon]

Sergio Della Franca wrote:
> Dear R-Helpers,
> 
> 
> I have the following data set(y):
> 
>   Test_Result   #_Test
>     t                 10
>     f                 14
>     f                 25
>     f                 NA
>     f                 40
>     t                45
>     t                44
>  <NA>           47
>     t                NA
> 
> 
> I want to replace the NA values with the following method:
> - for the numeric variable, replace NA with median
> - for character variable , replace NA with the most frequent level
> 
> If i use x<-na.roughfix(y) the NA values are correctly replaced.
> But if i x<-na.roughfix(y$Test_Result) i obtain the following error:
> 
> roughfix can only deal with numeric data.
> 
> How can i solve this proble that i met every time i want to replace only the
> NA values of a column (type character)?
> 
Hi Sergio,
In the prettyR package is the Mode function. This returns the mode of a 
vector as a character string. So I think this would do what you want:

library(prettyR)
testvec<-c(sample(LETTERS[1:4],20,TRUE),NA,NA)
testvec[is.na(testvec)]<-Mode(testvec)

You could do the same trick with the median function for the numeric values.

Jim