Converting empty values to NULL in R - Handling date column - r

Question

I have a simple dataframe as: dput(emp)
structure(list(name = structure(1L, .Label = "Alex", class = "factor"),
job = structure(1L, .Label = "", class = "factor"), Mgr = structure(1L, .Label = "", class = "factor"),
update = structure(18498, class = "Date")), class = "data.frame", row.names = c(NA,
-1L))
I want to convert all empty rows to NULL
The simplest way to achieve is:
emp[emp==""] <- NA
Which ofcourse would have worked but I get the error for the date column as:
Error in charToDate(x) :
character string is not in a standard unambiguous format
How can I convert all other empty rows to NULL without having to deal with the date column? Please note that the actual data frame has 30000+ rows.

Answer 1

Try formating the date variable as character, make the change and transform to date again:
#Format date
emp$update <- as.character(emp$update)
#Replace
emp[emp=='']<-NA
#Reformat date
emp$update <- as.Date(emp$update)
Output:
name job Mgr update
1 Alex <NA> <NA> 2020-08-24

Answer 2

You can try type.convert like below
type.convert(emp,as.is = TRUE)
such that
name job Mgr update
1 Alex NA NA 2020-08-24

Answer 3

You may try this using dplyr:
library(dplyr)
df %>%
mutate_at(vars(update),as.character) %>%
na_if(.,"")
As mentioned by #Duck, you have to format the date variable as character.
afterwards you can transform it back to date if you need it:
library(dplyr)
df %>%
mutate_at(vars(update),as.character) %>%
na_if(.,"") %>%
mutate_at(vars(update),as.Date)

Answer 4

See if this works:
> library(dplyr)
> library(purrr)
> emp <- structure(list(name = structure(1L, .Label = "Alex", class = "factor"),
+ job = structure(1L, .Label = "", class = "factor"), Mgr = structure(1L, .Label = "", class = "factor"),
+ update = structure(18498, class = "Date")), class = "data.frame", row.names = c(NA,
+ -1L))
> emp
name job Mgr update
1 Alex 2020-08-24
> emp %>% mutate(update = as.character(update)) %>% map_df(~gsub('^$',NA, .x)) %>% mutate(update = as.Date(update)) %>% mutate(across(1:3, as.factor))
# A tibble: 1 x 4
name job Mgr update
<fct> <fct> <fct> <date>
1 Alex NA NA 2020-08-24
>