[SOLVED] replace <NA> with NA

replace <NA> with NA

I have a data frame containing entries; It appears that these values are not treated as NA since is.na returns FALSE. I would like to convert these values to NA but could not find the way.

Solution

The two classes where this is likely to be an issue are character and factor. This should loop over a dtaframe and convert the "NA" values into true <NA>'s but just for those two classes:

make.true.NA <- function(x) if(is.character(x)||is.factor(x)){
                                  is.na(x) <- x=="NA"; x} else {
                                  x}
df[] <- lapply(df, make.true.NA)

(Untested in the absence of a data example.) The use of the form: df_name[] will attempt to retain the structure of the original dataframe which would otherwise lose its class attribute. I see that ujjwal thinks your spelling of NA has flanking "<>" characters so you might try this functions as more general:

make.true.NA <- function(x) if(is.character(x)||is.factor(x)){
                                  is.na(x) <- x %in% c("NA", "<NA>"); x} else {
                                  x}