Lubridate: duration() error when units repeats

[courtiol]

Hi all,
The outcome of duration() is inconsistant when vectors are use:

library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union
library(lubridate)
#> 
#> Attaching package: 'lubridate'
#> The following object is masked from 'package:base':
#> 
#>     date

tibble(age = 2, unit = "week") %>% mutate(duration(age, units = unit))
#> # A tibble: 1 x 3
#>     age unit  `duration(age, units = unit)`
#>   <dbl> <chr> <Duration>                   
#> 1     2 week  1209600s (~2 weeks)

tibble(age = 4, unit = "year") %>% mutate(duration(age, units = unit))
#> # A tibble: 1 x 3
#>     age unit  `duration(age, units = unit)`
#>   <dbl> <chr> <Duration>                   
#> 1     4 year  126144000s (~4 years)

tibble(age = c(2, 4), unit = c("week", "year")) %>% mutate(duration(age, units = unit))
#> # A tibble: 2 x 3
#>     age unit  `duration(age, units = unit)`
#>   <dbl> <chr> <Duration>                   
#> 1     2 week  1209600s (~2 weeks)          
#> 2     4 year  126144000s (~4 years)

tibble(age = c(2, 4), unit = c("week", "week")) %>% mutate(duration(age, units = unit))
#> Error: Invalid unit name: week

tibble(age = c(2, 4), unit = c("year", "year")) %>% mutate(duration(age, units = unit))
#> Error: Invalid unit name: year

tibble(age = c(2, 4), unit = "week") %>% mutate(duration(age, units = unit))
#> Error: Invalid unit name: week

tibble(age = c(2, 4), unit = "year") %>% mutate(duration(age, units = unit))
#> Error: Invalid unit name: year

devtools::session_info()
#> ─ Session info ──────────────────────────────────────────────────────────
#>  setting  value                       
#>  version  R version 3.6.0 (2019-04-26)
#>  os       macOS Mojave 10.14.5        
#>  system   x86_64, darwin15.6.0        
#>  ui       X11                         
#>  language (EN)                        
#>  collate  en_US.UTF-8                 
#>  ctype    en_US.UTF-8                 
#>  tz       Europe/Berlin               
#>  date     2019-07-02                  
#> 
#> ─ Packages ──────────────────────────────────────────────────────────────
#>  package     * version date       lib source        
#>  assertthat    0.2.1   2019-03-21 [1] CRAN (R 3.6.0)
#>  backports     1.1.4   2019-04-10 [1] CRAN (R 3.6.0)
#>  callr         3.2.0   2019-03-15 [1] CRAN (R 3.6.0)
#>  cli           1.1.0   2019-03-19 [1] CRAN (R 3.6.0)
#>  crayon        1.3.4   2017-09-16 [1] CRAN (R 3.6.0)
#>  desc          1.2.0   2018-05-01 [1] CRAN (R 3.6.0)
#>  devtools      2.0.2   2019-04-08 [1] CRAN (R 3.6.0)
#>  digest        0.6.19  2019-05-20 [1] CRAN (R 3.6.0)
#>  dplyr       * 0.8.2   2019-06-29 [1] CRAN (R 3.6.0)
#>  evaluate      0.14    2019-05-28 [1] CRAN (R 3.6.0)
#>  fansi         0.4.0   2018-10-05 [1] CRAN (R 3.6.0)
#>  fs            1.3.1   2019-05-06 [1] CRAN (R 3.6.0)
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#>  highr         0.8     2019-03-20 [1] CRAN (R 3.6.0)
#>  htmltools     0.3.6   2017-04-28 [1] CRAN (R 3.6.0)
#>  knitr         1.23    2019-05-18 [1] CRAN (R 3.6.0)
#>  lubridate   * 1.7.4   2018-04-11 [1] CRAN (R 3.6.0)
#>  magrittr      1.5     2014-11-22 [1] CRAN (R 3.6.0)
#>  memoise       1.1.0   2017-04-21 [1] CRAN (R 3.6.0)
#>  pillar        1.4.2   2019-06-29 [1] CRAN (R 3.6.0)
#>  pkgbuild      1.0.3   2019-03-20 [1] CRAN (R 3.6.0)
#>  pkgconfig     2.0.2   2018-08-16 [1] CRAN (R 3.6.0)
#>  pkgload       1.0.2   2018-10-29 [1] CRAN (R 3.6.0)
#>  prettyunits   1.0.2   2015-07-13 [1] CRAN (R 3.6.0)
#>  processx      3.3.1   2019-05-08 [1] CRAN (R 3.6.0)
#>  ps            1.3.0   2018-12-21 [1] CRAN (R 3.6.0)
#>  purrr         0.3.2   2019-03-15 [1] CRAN (R 3.6.0)
#>  R6            2.4.0   2019-02-14 [1] CRAN (R 3.6.0)
#>  Rcpp          1.0.1   2019-03-17 [1] CRAN (R 3.6.0)
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#>  rlang         0.4.0   2019-06-25 [1] CRAN (R 3.6.0)
#>  rmarkdown     1.13    2019-05-22 [1] CRAN (R 3.6.0)
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#>  sessioninfo   1.1.1   2018-11-05 [1] CRAN (R 3.6.0)
#>  stringi       1.4.3   2019-03-12 [1] CRAN (R 3.6.0)
#>  stringr       1.4.0   2019-02-10 [1] CRAN (R 3.6.0)
#>  testthat      2.1.1   2019-04-23 [1] CRAN (R 3.6.0)
#>  tibble        2.1.3   2019-06-06 [1] CRAN (R 3.6.0)
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#>  vctrs         0.1.0   2018-11-29 [1] CRAN (R 3.6.0)
#>  withr         2.1.2   2018-03-15 [1] CRAN (R 3.6.0)
#>  xfun          0.8     2019-06-25 [1] CRAN (R 3.6.0)
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#>  zeallot       0.1.0   2018-01-28 [1] CRAN (R 3.6.0)
#> 
#> [1] /Library/Frameworks/R.framework/Versions/3.6/Resources/library

^{Created on 2019-07-02 by the reprex package (v0.3.0)}

It would be great if the vectorial form would always work.

PS: why does year works when the doc says "Units larger than weeks are not used due to their variability."...? I am happy it does though.

Alex

[yogat3ch]

Hi @courtiol,
This is a common issue with all non-vectorized functions using mutate. There's a simple solution, add dplyr::rowwise() like so:

tibble(age = c(2, 4), unit = c("week", "week")) %>% dplyr::rowwise() %>% mutate(duration(age, units = unit))

[courtiol]

Hi @yogat3ch, thanks for your feedback.

I would be OK with the fact that duration is not a vectorised function, but my example show that it behave inconsistently despite alternative inputs being of same dimension and class.

As such lubridate::duration() seem to violate a core tidy principle.

The issue applies outside a mutate call, so I am not sure that the problem falls under "common issue".

```{r}

lubridate::duration(c(1,2), units = c("days", "weeks"))
[1] "86400s (~1 days)" "1209600s (~2 weeks)"
lubridate::duration(c(1,2), units = c("weeks", "weeks"))
Error: Invalid unit name: weeks
`` Sincedplyr::rowwise()is labelled asquestioning` with respect to its status, I also think it would be best not to have to rely on that and ideally offer instead true vectorisation support.

What do you think?

Best,
Alex

[yogat3ch]

Hi Alex @courtiol,
I think the unexpected behavior definitely merits the attention of the lubridate developers, so thank you for posting it here. It seems like they're pretty inundated with issues though so I wanted to offer the workaround so you can move forward with whatever you're working on.
That surprises me about rowwise, as that function is essential when writing custom mutate functions as the single use case function is definitely simpler to write up and plug in to mutate with a call to rowwise than have to write every custom function for mutate as vectorised.
I definitely don't think they should sunset rowwise.

Thanks for the response!

[hadley]

@courtiol could you please provide a minimal reprex, focussing on the problem you're experiencing? Please eliminate the use of dplyr and don't include session info.

[courtiol]

Hi @hadley, I did as you suggested:

works <- data.frame(age = c(2, 4), unit = c("year", "week"))
works$age <- lubridate::duration(works$age, units = works$unit)

doesnotwork <- data.frame(age = c(2, 4), unit = c("year", "year"))
doesnotwork$age <- lubridate::duration(doesnotwork$age, units = doesnotwork$unit)
#> Error: Invalid unit name: year

<sup>Created on 2019-11-20 by the reprex package (v0.3.0)</sup>

[hadley]

Even more minimal reprex 😄

library(lubridate, warn.conflicts = FALSE)

duration(1:2, c("seconds", "minutes"))
#> [1] "1s"                "120s (~2 minutes)"
duration(1:2, c("seconds", "seconds"))
#> Error: Invalid unit name: seconds

<sup>Created on 2019-11-20 by the reprex package (v0.3.0)</sup>