Class modification when using lcd

[TaniaAlarcon]

The lcd package adds the word "lcd" to the object class, which causes problems when working with other R packages.

function (station, year, ...) 
{
    assert(station, c("character", "numeric", "integer"))
    assert(year, c("character", "numeric", "integer"))
    assert_range(year, 1901:format(Sys.Date(), "%Y"))
    path <- lcd_get(station = station, year = year, ...)
    tmp <- safe_read_csv(path)
    names(tmp) <- tolower(names(tmp))
    df <- tibble::as_tibble(tmp)
    structure(df, class = c(class(df), "lcd")) # // adding the class attribute
}

Here is a sample data set:

Year    <- seq(from = 2000, to = 2003)
Station <- c(72658014922)
dat     <- crossing(Station, Year)

I use map to get NOAA's LCD records for each year in the data.

dat <- dat %>% 
  mutate(RawData = map2(Station, Year, lcd))

When I check class for the RawData, I get the following:

class(dat$RawData[[1]])

"tbl_df"     "tbl"        "data.frame" "lcd"   

Since there is this strange "lcd" included in the class, any call to RawData gives this error:

dat <- dat %>%
  mutate(RawData = map(RawData, ~mutate_all(., as.character)))

Error: Problem with `mutate()` input `RawData`.
x `x` must be a vector, not a `tbl_df/tbl/data.frame/lcd` object.
i Input `RawData` is `map(RawData, ~mutate_all(., as.character))`.

I can get around this error by converting RawData back to tibbles.

What is the reason for having the lcd function modify the object class?

Here is my session information:

Session Info

 setting  value                       
 version  R version 4.0.2 (2020-06-22)
 os       Windows 10 x64              
 system   i386, mingw32               
 ui       RStudio                     
 language (EN)                        
 collate  English_United States.1252  
 ctype    English_United States.1252  
 tz       America/New_York            
 date     2020-08-07                  

- Packages ---------------------------------------------------------------------------------------------------------------------------------------------------------
 package     * version  date       lib source        
 assertthat    0.2.1    2019-03-21 [1] CRAN (R 4.0.2)
 backports     1.1.8    2020-06-17 [1] CRAN (R 4.0.2)
 blob          1.2.1    2020-01-20 [1] CRAN (R 4.0.2)
 broom         0.7.0    2020-07-09 [1] CRAN (R 4.0.2)
 callr         3.4.3    2020-03-28 [1] CRAN (R 4.0.2)
 cellranger    1.1.0    2016-07-27 [1] CRAN (R 4.0.2)
 cli           2.0.2    2020-02-28 [1] CRAN (R 4.0.2)
 colorspace    1.4-1    2019-03-18 [1] CRAN (R 4.0.2)
 crayon        1.3.4    2017-09-16 [1] CRAN (R 4.0.2)
 crul          1.0.0    2020-07-30 [1] CRAN (R 4.0.2)
 curl          4.3      2019-12-02 [1] CRAN (R 4.0.2)
 DBI           1.1.0    2019-12-15 [1] CRAN (R 4.0.2)
 dbplyr        1.4.4    2020-05-27 [1] CRAN (R 4.0.2)
 desc          1.2.0    2018-05-01 [1] CRAN (R 4.0.2)
 devtools      2.3.1    2020-07-21 [1] CRAN (R 4.0.2)
 digest        0.6.25   2020-02-23 [1] CRAN (R 4.0.2)
 dplyr       * 1.0.1    2020-07-31 [1] CRAN (R 4.0.2)
 ellipsis      0.3.1    2020-05-15 [1] CRAN (R 4.0.2)
 fansi         0.4.1    2020-01-08 [1] CRAN (R 4.0.2)
 forcats     * 0.5.0    2020-03-01 [1] CRAN (R 4.0.2)
 fs            1.5.0    2020-07-31 [1] CRAN (R 4.0.2)
 generics      0.0.2    2018-11-29 [1] CRAN (R 4.0.2)
 ggplot2     * 3.3.2    2020-06-19 [1] CRAN (R 4.0.2)
 glue          1.4.1    2020-05-13 [1] CRAN (R 4.0.2)
 gridExtra     2.3      2017-09-09 [1] CRAN (R 4.0.2)
 gtable        0.3.0    2019-03-25 [1] CRAN (R 4.0.2)
 haven         2.3.1    2020-06-01 [1] CRAN (R 4.0.2)
 hms           0.5.3    2020-01-08 [1] CRAN (R 4.0.2)
 hoardr        0.5.2    2018-12-02 [1] CRAN (R 4.0.2)
 httpcode      0.3.0    2020-04-10 [1] CRAN (R 4.0.2)
 httr          1.4.2    2020-07-20 [1] CRAN (R 4.0.2)
 jsonlite      1.7.0    2020-06-25 [1] CRAN (R 4.0.2)
 lifecycle     0.2.0    2020-03-06 [1] CRAN (R 4.0.2)
 lubridate     1.7.9    2020-06-08 [1] CRAN (R 4.0.2)
 magrittr      1.5      2014-11-22 [1] CRAN (R 4.0.2)
 memoise       1.1.0    2017-04-21 [1] CRAN (R 4.0.2)
 modelr        0.1.8    2020-05-19 [1] CRAN (R 4.0.2)
 munsell       0.5.0    2018-06-12 [1] CRAN (R 4.0.2)
 pillar        1.4.6    2020-07-10 [1] CRAN (R 4.0.2)
 pkgbuild      1.1.0    2020-07-13 [1] CRAN (R 4.0.2)
 pkgconfig     2.0.3    2019-09-22 [1] CRAN (R 4.0.2)
 pkgload       1.1.0    2020-05-29 [1] CRAN (R 4.0.2)
 prettyunits   1.1.1    2020-01-24 [1] CRAN (R 4.0.2)
 processx      3.4.3    2020-07-05 [1] CRAN (R 4.0.2)
 ps            1.3.3    2020-05-08 [1] CRAN (R 4.0.2)
 purrr       * 0.3.4    2020-04-17 [1] CRAN (R 4.0.2)
 R6            2.4.1    2019-11-12 [1] CRAN (R 4.0.2)
 rappdirs      0.3.1    2016-03-28 [1] CRAN (R 4.0.2)
 Rcpp          1.0.5    2020-07-06 [1] CRAN (R 4.0.2)
 readr       * 1.3.1    2018-12-21 [1] CRAN (R 4.0.2)
 readxl        1.3.1    2019-03-13 [1] CRAN (R 4.0.2)
 remotes       2.2.0    2020-07-21 [1] CRAN (R 4.0.2)
 reprex        0.3.0    2019-05-16 [1] CRAN (R 4.0.2)
 rlang         0.4.7    2020-07-09 [1] CRAN (R 4.0.2)
 rnoaa       * 1.1.0    2020-07-08 [1] CRAN (R 4.0.2)
 rprojroot     1.3-2    2018-01-03 [1] CRAN (R 4.0.2)
 rstudioapi    0.11     2020-02-07 [1] CRAN (R 4.0.2)
 rvest         0.3.6    2020-07-25 [1] CRAN (R 4.0.2)
 scales        1.1.1    2020-05-11 [1] CRAN (R 4.0.2)
 sessioninfo   1.1.1    2018-11-05 [1] CRAN (R 4.0.2)
 stringi       1.4.6    2020-02-17 [1] CRAN (R 4.0.0)
 stringr     * 1.4.0    2019-02-10 [1] CRAN (R 4.0.2)
 testthat      2.3.2    2020-03-02 [1] CRAN (R 4.0.2)
 tibble      * 3.0.3    2020-07-10 [1] CRAN (R 4.0.2)
 tidyr       * 1.1.1    2020-07-31 [1] CRAN (R 4.0.2)
 tidyselect    1.1.0    2020-05-11 [1] CRAN (R 4.0.2)
 tidyverse   * 1.3.0    2019-11-21 [1] CRAN (R 4.0.2)
 usethis       1.6.1    2020-04-29 [1] CRAN (R 4.0.2)
 vctrs         0.3.2    2020-07-15 [1] CRAN (R 4.0.2)
 withr         2.2.0    2020-04-20 [1] CRAN (R 4.0.2)
 XML           3.99-0.5 2020-07-23 [1] CRAN (R 4.0.2)
 xml2          1.3.2    2020-04-23 [1] CRAN (R 4.0.2)

[sckott]

Are you sure the problem is with lcd as part of the class info? I can't replicate your code (i dont know where crossing comes from). You're calling as.character() on a data.frame and the error is saying mutate expects a vector, which suggests to me it's expecting a vector of items, not a data.frame.

[TaniaAlarcon]

Crossing is a tidyverse function: https://tidyr.tidyverse.org/reference/expand.html
I can use a more straight forward example:

dat <- lcd(72658014922, 2000)

class(dat)

[1] "tbl_df"     "tbl"        "data.frame" "lcd" 

The problem appears to be the modification of the class with the word "lcd". The source code for the lcd function shows that this modification happens in the last line of the lcd function:

lcd <- function(station, year, ...) {
  assert(station, c("character", "numeric", "integer"))
  assert(year, c("character", "numeric", "integer"))
  assert_range(year, 1901:format(Sys.Date(), "%Y"))

  path <- lcd_get(station = station, year = year, ...)
  tmp <- safe_read_csv(path)
  names(tmp) <- tolower(names(tmp))
  df <- tibble::as_tibble(tmp)
  structure(df, class = c(class(df), "lcd"))
}

[sckott]

fixed now