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Load objects from RData / qs2 / rds / feather file

Source: R/general_load_as.R
load_as.Rd

This function loads an RData file specified by the file parameter. If the RData file contains a single object, that object is returned directly. If the file contains multiple objects, they are returned as a list with each object accessible by its name. This allows for flexible handling of loaded data without needing to know the names of the objects stored within the RData file ahead of time. The function also supports loading feather, qs2 and rds files.

Usage

load_as(file = NULL, n_threads = 1L, timeout = 300L, ...)

Arguments

file

Character. the file path or URL of the file to be loaded. If file is a URL, the function will download the file from the URL to a temporary file and load it.

n_threads

Number of threads to use when reading qs2 files. See qs2::qs_read.

timeout

integer; time in seconds before the download times out. Default 300 seconds; see download.file.

...

Additional arguments to be passed to the respective load functions. base::load for RData files; qs2::qs_read for qs2 files; arrow::read_feather for feather files; and base::readRDS for rds files.

Value

Depending on the contents of the RData file, this function returns either a single R object or a named list of R objects. The names of the list elements (if a list is returned) correspond to the names of the objects stored within the RData file.

Author

Ahmed El-Gabbas

Examples


file <- system.file("testdata", "culcita_dat.RData", package = "lme4")

# ---------------------------------------------------------
# loading RData using base::load
# ---------------------------------------------------------
(load(file))
#> [1] "culcita_dat"

ls()
#> [1] "culcita_dat" "file"       

tibble::tibble(culcita_dat)
#> # A tibble: 80 × 3
#>    block predation ttt  
#>    <fct>     <dbl> <fct>
#>  1 1             0 none 
#>  2 1             1 none 
#>  3 2             1 none 
#>  4 2             1 none 
#>  5 3             1 none 
#>  6 3             1 none 
#>  7 4             1 none 
#>  8 4             1 none 
#>  9 5             1 none 
#> 10 5             1 none 
#> # ℹ 70 more rows

# ---------------------------------------------------------
# Loading as custom object name
# ---------------------------------------------------------
NewObj <- load_as(file = file)

ls()
#> [1] "NewObj"      "culcita_dat" "file"       

print(tibble::tibble(NewObj))
#> # A tibble: 80 × 3
#>    block predation ttt  
#>    <fct>     <dbl> <fct>
#>  1 1             0 none 
#>  2 1             1 none 
#>  3 2             1 none 
#>  4 2             1 none 
#>  5 3             1 none 
#>  6 3             1 none 
#>  7 4             1 none 
#>  8 4             1 none 
#>  9 5             1 none 
#> 10 5             1 none 
#> # ℹ 70 more rows

# ---------------------------------------------------------
# Loading multiple objects stored in single RData file
# ---------------------------------------------------------

# store three objects to single RData file
mtcars2 <- mtcars3 <- mtcars

# save in the order of mtcars2, mtcars3, mtcars
TempFile_1 <- tempfile(pattern = "mtcars_", fileext = ".RData")
save(mtcars2, mtcars3, mtcars, file = TempFile_1)

# save in another order: mtcars, mtcars2, mtcars3
TempFile_2 <- tempfile(pattern = "mtcars_", fileext = ".RData")
save(mtcars, mtcars2, mtcars3, file = TempFile_2)


# loading as a single list  with 3 items, keeping original order
mtcars_all_1 <- load_as(TempFile_1)
str(mtcars_all_1, 1)
#> List of 3
#>  $ mtcars2:'data.frame':	32 obs. of  11 variables:
#>  $ mtcars3:'data.frame':	32 obs. of  11 variables:
#>  $ mtcars :'data.frame':	32 obs. of  11 variables:

mtcars_all_2 <- load_as(TempFile_2)
str(mtcars_all_2, 1)
#> List of 3
#>  $ mtcars :'data.frame':	32 obs. of  11 variables:
#>  $ mtcars2:'data.frame':	32 obs. of  11 variables:
#>  $ mtcars3:'data.frame':	32 obs. of  11 variables: