Merging two lines of code into one using indexing or any other tool-CodePudding

I have two differnet lines of code which performing same thing but for two different columns. I tried different methods to merge them into just one line of code but everytime I get an error.

Code is just to tranform datetime column from chr to dttm:

df[["started_at"]] <- as.POSIXct(df[["started_at"]], format = "%Y-%m-%d %H:%M:%S") %>% ymd_hms()
df[["ended_at"]] <- as.POSIXct(df[["ended_at"]], format = "%Y-%m-%d %H:%M:%S") %>% ymd_hms()

CodePudding user response：

If you are comfortable with the package dplyr, you can use mutate() with across().

Input

I've created a dummy dataframe df for demonstration.

library(dplyr)
library(lubridate)

# dummy dataframe
df <- tibble(started_at = "2020-01-30 11:11:11", 
             ended_at = "2020-12-06 15:43:26", 
             ID = "123")

# A tibble: 1 × 3
  started_at          ended_at            ID   
  <chr>               <chr>               <chr>
1 2020-01-30 11:11:11 2020-12-06 15:43:26 123

Solution

df <- df %>% mutate(across(c(started_at, ended_at), 
                           ~ as.POSIXct(.x, format = "%Y-%m-%d %H:%M:%S") %>% 
                             ymd_hms()))

# A tibble: 1 × 3
  started_at          ended_at            ID   
  <dttm>              <dttm>              <chr>
1 2020-01-30 11:11:11 2020-12-06 15:43:26 123

CodePudding user response：

Any of

df %>% mutate(across(c(started_at, ended_at), as.POSIXct))
df %>% mutate(across(c(started_at, ended_at), ymd_hms))

will coerce to class "POSIXct".
If you know that the date/time columns are the only ones ending in "_at" , you can simplify the code above to any of

df %>% mutate(across(ends_with("_at"), as.POSIXct))
df %>% mutate(across(ends_with("_at"), ymd_hms))

On both case, the rule is

If you want to avoid loading another package, lubridate, just for this, use the code line calling as.POSIXct.
If you need more date and time functions, to load and use package lubridate is probably a good idea.