Experiencing a crash on my R script

[jrkrideau]

I think you are missing some code in the message. The code block below i tried adding is blank.

[happyme]

as.difftime instead of just difftime

[jrkrideau]

Oh, okay. My reading of the help is that is that it is intended to translate other date formats in other packages into {lubridate} format so "NA" is what you would expect here.

Are you still getting this error?

Error in as.POSIXlt.character(x, tz, ...) :
character string is not in a standard unambiguous format.

It looks like it is telling us that it thinks that one or both of

all_trips$started_at
all_trips$ended_at

is not in standard POSIXct format. Weird' as my version is working fine.
Try

class(all_trips$started_at)
class(all_trips$ended_at)

In both cases the output should be:

"POSIXct" "POSIXt"

[happyme]

Yes that's what I am getting

[jrkrideau]

Can you run the script again and copy all the error message(s) again between the
```

```

Maybe a cleaner layout may help.

Also try

all_trips$ended_at[1]
all_trips$started_at[1]

I get

> all_trips$ended_at[1]
[1] "2019-01-01 00:11:07 UTC"
> all_trips$started_at[1]
[1] "2019-01-01 00:04:37 UTC"

[happyme]

Error in class(all_trips$ended_at, all_trips$started_at) :
2 arguments passed to 'class' which requires 1

[happyme]

Error: unexpected symbol in:
"

all_trips"

[happyme]

Error: unexpected symbol in:
"all_trips$ride_length <- difftime(all_trips$ended_at[1]
all_trips"

thats the error I am getting doing

all_trips$ride_length <- difftime(all_trips$ended_at[1], all_trips$started_at[1])

on here I noticed when I add a delimiter (```), the code chunk wouldn't show, hence my copying and pasting as it is.

[jrkrideau]

When all else fails, read the manual. I just realized that difftime is base R not (lubridate). That does not explain why your script is working and mine appears to be but it may be relevant. It occurs to me I have not actually checked the accuracy of what I am getting.

I have to go out for two or three hours. If all you need is ride duration, I wonder if this would do as a work-around for the moment.
Example

t1 <- ymd_hms("2024-04-25 10:00:00")
t2 <- ymd_hms("2024-04-25 14:15:00")

(t2 - t1) 
Time difference of 4.25 hours

Therefore

(t2 - t1)  %>%  as.numeric
4.25

[happyme]

Thanks so much for all your effort.

I actually want "ride_length" calculation to all_trips (in seconds).
hence the:
code: all_trips$ride_length <- difftime(all_trips$ended_at,
all_trips$started_at)

but if I write same code as : all_trips$ride_length <- as.difftime(all_trips$ended_at,
all_trips$started_at)

inserting as.difftime, it runs well and returns

tibble [791,956 × 15] (S3: tbl_df/tbl/data.frame)
ride_id : chr [1:791956] "21742443" "21742444" "21742445" "21742446" ... started_at : chr [1:791956] "2019-01-01 0:04:37" "2019-01-01 0:08:13" "2019-01-01 0:13:23" "2019-01-01 0:13:45" ...
ended_at : chr [1:791956] "2019-01-01 0:11:07" "2019-01-01 0:15:34" "2019-01-01 0:27:12" "2019-01-01 0:43:28" ... rideable_type : chr [1:791956] "2167" "4386" "1524" "252" ...
start_station_id : num [1:791956] 199 44 15 123 173 98 98 211 150 268 ... start_station_name: chr [1:791956] "Wabash Ave & Grand Ave" "State St & Randolph St" "Racine Ave & 18th St" "California Ave & Milwaukee Ave" ...
end_station_id : num [1:791956] 84 624 644 176 35 49 49 142 148 141 ... end_station_name : chr [1:791956] "Milwaukee Ave & Grand Ave" "Dearborn St & Van Buren St ()" "Western Ave & Fillmore St ()" "Clark St & Elm St" ...
member_casual : chr [1:791956] "member" "member" "member" "member" ... date : Date[1:791956], format: "2019-01-01" ...
month : chr [1:791956] "01" "01" "01" "01" ... day : chr [1:791956] "01" "01" "01" "01" ...
year : chr [1:791956] "2019" "2019" "2019" "2019" ... day_of_week : chr [1:791956] "Tuesday" "Tuesday" "Tuesday" "Tuesday" ...
$ ride_length : 'difftime' num [1:791956] NA NA NA NA ...
..- attr(*, "units")= chr "secs"
Show in New Window
[1] FALSE
Show in New Window
[1] TRUE
Show in New Window

when i do a mean calculation
mean(all_trips_v2$ride_length)
{NA}

so with that I would have anything to aggregate, so it definitely means something is wrong somewhere.

[jrkrideau]

• as.difftime* is a translator. It will not calculate anything so "NA" is exactly what we would expect.

I have not decided whether I am more surprised that your version of the script does not run or that my version does.

Anyway, let's try a completely different approach using pure {lubridate}.
Replace

all_trips$ride_length <- difftime(all_trips$ended_at,all_trips$started_at)

with

all_trips$ride_duration <- as.duration(all_trips$started_at %--% all_trips$ended_at)  %>%  as.numeric()

This will give you the number of seconds duration in the ride. I just changed ride_length to ride_duration to keep it simple while I was experimenting. The name really does not matter.

Here is a bit of code that should (hopefully) give you some idea of what is happening.

library(tidyverse)
t1 <- ymd_hms("2024-04-22 10:00:00")
t2 <- ymd_hms("2024-04-25 14:15:00")

time.interval <- t1 %--% t2 # example of calculating the time interval.

as.duration(t1 %--% t2)  %>%  as.numeric()

[happyme]

Alright, thanks will try it now, I had actually given up on using R and moved over to spread sheet. But I will reinstall my R studio now and try this out. Thank you so much for your assistance.

[jrkrideau]

No! No! Not a spreadsheet! Spreadsheets are evil!
More to the point spreadsheets are horribly error-prone.

Here is a very famous case The Reinhart-Rogoff error – or how not to Excel at economics

One of the authors has an Economics Nobel.

[happyme]

@jrkrideau

all_trips$ride_duration <- as.duration(all_trips$started_at %--% all_trips$ended_at) %>% as.numeric()

This worked perfectly. thank you sooo much.

[happyme]

Alright, would check this out.
Thanks.