CODEWITHSUNDEEP
rtidyverselubridatetsibble
manuzambo
manuzambo

Reputation: 211

How can i obtain a tsibble from this tibble without using the as.Date function?

I need to convert several "tibble" into "tsibble".

Here a simple example:

require(tidyverse)
require(lubridate)

time_1 <- c(ymd_hms('20210101 000000'),
            ymd_hms('20210101 080000'),
            ymd_hms('20210101 160000'),
            # ymd_hms('20210102 000000'),
            ymd_hms('20210102 080000'),
            ymd_hms('20210102 160000'))

df_1 <- tibble(time_1, y=rnorm(5))

df_1 %>% 
  as_tsibble(index=time_1)

This chunk of code works as expected. But, if the dates are all midnights, this code throws an error:

time_2 <- c(ymd_hms('20210101 000000'),
            ymd_hms('20210102 000000'),
            ymd_hms('20210103 000000'),
            # ymd_hms('20210104 000000'),
            ymd_hms('20210105 000000'),
            ymd_hms('20210106 000000'))

df_2 <- tibble(time_2, y=rnorm(5))

df_2 %>% 
  as_tsibble(index=time_2)

I don't want to solve this issue in this way because the as.Date function changes the column type.

df_2 %>% 
  mutate(time_2=as.Date(time_2)) %>% 
  as_tsibble(index=time_2)

I also don't want to fix the issue in this way because after converting the tibble into tsibble i need to apply the fill_gaps function, which doesn't create the ymd_hms('20210104 000000') in this second scenario.

df_2 %>% 
  as_tsibble(index=time_2, regular=FALSE)

Is this a bug?

Thanks.

Upvotes: 1

Views: 446

Answers (1)

Mitchell O&#39;Hara-Wild
Mitchell O&#39;Hara-Wild

Reputation: 2459

This behaviour is explained in tsibble's FAQ.

Essentially subdaily data (ymd_hms()) measured at midnight each day doesn't necessarily have an interval of 1 day (24 hours). Consider that some days have shifts due to daylight savings in your time zone, and so the number of hours between midnight and midnight the next day may be 23 or 25 hours.

If you're working with data measured at a daily interval, you should use a date with ymd() precision. You can covert it back to a date time using as_datetime() if you like.

Personally I don't think this should produce an error, however it is much simpler if it does. Perhaps the appropriate interval here is 1 hour or 30 minutes (or whatever is appropriate for timezone shifts in the specified timezone).

Upvotes: 2

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