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Apply a function over rows of a data.frame-like object and concatenate the results back to tibble or data.frame.

Source: R/utils.R
lapply_rows.Rd

Inside a FUN, a row of df will be available as a list or scdrake_list() (default). The FUN must return a named list for a proper concatenation of the results. The named list can also contain elements of a length other than one, which are then wrapped in list().

Usage

lapply_rows(df, as_scdrake_list = TRUE, return_tibble = TRUE, FUN, ...)

Arguments

df

A data.frame-like object.

as_scdrake_list

A logical scalar: if TRUE, each row-list in FUN will be converted to scdrake_list().

return_tibble

If TRUE, a tibble with concatenated results is returned. Otherwise results are coerced to data.frame and original rownames are set.

FUN

A function to apply over df rows.

...

Additional arguments passed to FUN.

Value

tibble or data.frame according to the return_tibble parameter.

Examples

library(magrittr)

fn <- function(row_list) {
  row_list$cyl_2 <- row_list$cyl**2
  row_list$colors <- c("red", "green", "blue")
  row_list$sublist <- mtcars[1:5, 1:5]
  return(row_list)
}

df <- lapply_rows(mtcars, FUN = fn)
head(df)
#> # A tibble: 6 × 14
#>     mpg   cyl  disp    hp  drat    wt  qsec    vs    am  gear  carb cyl_2 colors
#>   <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <list>
#> 1  21       6   160   110  3.9   2.62  16.5     0     1     4     4    36 <chr> 
#> 2  21       6   160   110  3.9   2.88  17.0     0     1     4     4    36 <chr> 
#> 3  22.8     4   108    93  3.85  2.32  18.6     1     1     4     1    16 <chr> 
#> 4  21.4     6   258   110  3.08  3.22  19.4     1     0     3     1    36 <chr> 
#> 5  18.7     8   360   175  3.15  3.44  17.0     0     0     3     2    64 <chr> 
#> 6  18.1     6   225   105  2.76  3.46  20.2     1     0     3     1    36 <chr> 
#> # … with 1 more variable: sublist <list>

df2 <- lapply_rows(mtcars, return_tibble = FALSE, FUN = fn)
head(df2)
#>                    mpg cyl disp  hp drat    wt  qsec vs am gear carb cyl_2
#> Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4    36
#> Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4    36
#> Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1    16
#> Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1    36
#> Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2    64
#> Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1    36
#>                             colors
#> Mazda RX4         red, green, blue
#> Mazda RX4 Wag     red, green, blue
#> Datsun 710        red, green, blue
#> Hornet 4 Drive    red, green, blue
#> Hornet Sportabout red, green, blue
#> Valiant           red, green, blue
#>                                                                                                                                                                                        sublist
#> Mazda RX4         21.00, 21.00, 22.80, 21.40, 18.70, 6.00, 6.00, 4.00, 6.00, 8.00, 160.00, 160.00, 108.00, 258.00, 360.00, 110.00, 110.00, 93.00, 110.00, 175.00, 3.90, 3.90, 3.85, 3.08, 3.15
#> Mazda RX4 Wag     21.00, 21.00, 22.80, 21.40, 18.70, 6.00, 6.00, 4.00, 6.00, 8.00, 160.00, 160.00, 108.00, 258.00, 360.00, 110.00, 110.00, 93.00, 110.00, 175.00, 3.90, 3.90, 3.85, 3.08, 3.15
#> Datsun 710        21.00, 21.00, 22.80, 21.40, 18.70, 6.00, 6.00, 4.00, 6.00, 8.00, 160.00, 160.00, 108.00, 258.00, 360.00, 110.00, 110.00, 93.00, 110.00, 175.00, 3.90, 3.90, 3.85, 3.08, 3.15
#> Hornet 4 Drive    21.00, 21.00, 22.80, 21.40, 18.70, 6.00, 6.00, 4.00, 6.00, 8.00, 160.00, 160.00, 108.00, 258.00, 360.00, 110.00, 110.00, 93.00, 110.00, 175.00, 3.90, 3.90, 3.85, 3.08, 3.15
#> Hornet Sportabout 21.00, 21.00, 22.80, 21.40, 18.70, 6.00, 6.00, 4.00, 6.00, 8.00, 160.00, 160.00, 108.00, 258.00, 360.00, 110.00, 110.00, 93.00, 110.00, 175.00, 3.90, 3.90, 3.85, 3.08, 3.15
#> Valiant           21.00, 21.00, 22.80, 21.40, 18.70, 6.00, 6.00, 4.00, 6.00, 8.00, 160.00, 160.00, 108.00, 258.00, 360.00, 110.00, 110.00, 93.00, 110.00, 175.00, 3.90, 3.90, 3.85, 3.08, 3.15