I am writing a function to produce a frequency table using prop.table, and want to produce this for several categorical variables in the data set.
I am using datasets::mtcars for this example. I am looking to write the function with a group_by on the binary variable "am" in the dataset, so the output is stratified by am == 1 and am == 0.
For this code, is there a way to add a group_by statement?
summary(mtcars)
apply(mtcars[c("cyl", "gear", "carb")], 2,
\(x) prop.table(table(x, useNA = "always"))*100)
You can use by() in base R:
by(mtcars, mtcars$am, function(mt_am)
sapply(mt_am[c("cyl", "gear", "carb")],
function(mt_col) prop.table(table(mt_col, useNA = "always"))*100))
#> mtcars$am: 0
#> $cyl
#> mt_col
#> 4 6 8 <NA>
#> 15.78947 21.05263 63.15789 0.00000
#>
#> $gear
#> mt_col
#> 3 4 <NA>
#> 78.94737 21.05263 0.00000
#>
#> $carb
#> mt_col
#> 1 2 3 4 <NA>
#> 15.78947 31.57895 15.78947 36.84211 0.00000
#>
#> ------------------------------------------------------------
#> mtcars$am: 1
#> $cyl
#> mt_col
#> 4 6 8 <NA>
#> 61.53846 23.07692 15.38462 0.00000
#>
#> $gear
#> mt_col
#> 4 5 <NA>
#> 61.53846 38.46154 0.00000
#>
#> $carb
#> mt_col
#> 1 2 4 6 8 <NA>
#> 30.769231 30.769231 23.076923 7.692308 7.692308 0.000000