How can I change date string to POSIXct format?-CodePudding

I am trying to convert these dates in created_at column to the number of seconds column created_at_dt using POSIXct.

created_at
<chr>
Fri May 26 17:30:01  0000 2017              
Fri May 26 17:30:05  0000 2017              
Fri May 26 17:30:05  0000 2017              
Fri May 26 17:30:04  0000 2017              
Fri May 26 17:30:12  0000 2017

Example of what i want to achieve:

created_at_dt
<dbl>
1495819801              
1495819805              
1495819805              
1495819804              
1495819812

I tried the following line but got only NA values introduced.

tweets <- tweets %>% 
   mutate(created_at_dt = asPOSIXct(as.numeric('created_at')))

Any help would be much appreciated. Thank you!

CodePudding user response：

You just need to specify the correct format string for as.POSIXct.

Also, created_at should not be in quotes for mutate().

library(dplyr)

tweets <- tweets %>% 
  mutate(created_at_dt = as.POSIXct(created_at, 
                                    format = "%a %B %d %H:%M:%S %z %Y") %>%
                                      as.numeric())

Result:

                      created_at created_at_dt
1 Fri May 26 17:30:01  0000 2017    1495819801
2 Fri May 26 17:30:05  0000 2017    1495819805
3 Fri May 26 17:30:05  0000 2017    1495819805
4 Fri May 26 17:30:04  0000 2017    1495819804
5 Fri May 26 17:30:12  0000 2017    1495819812

The data:

tweets <- structure(list(created_at = c("Fri May 26 17:30:01  0000 2017", 
"Fri May 26 17:30:05  0000 2017", "Fri May 26 17:30:05  0000 2017", 
"Fri May 26 17:30:04  0000 2017", "Fri May 26 17:30:12  0000 2017"
)), class = "data.frame", row.names = c(NA, -5L))