Apply list of functions to input

Apply list of functions to input

Usage

function_list(..., stringsAsFactors = FALSE, check.names = TRUE)

Arguments

...

Named or unnamed arguments, each of which is a function taking exactly one input. See details.

stringsAsFactors, check.names

Arguments of data.frame.

Value

Function with a single input which outputs a data.frame. Has special 'flist' entry in its environment which stores individual functions as list.

Details

This is a convenience function which takes a number of functions and returns another function which applies all of the user specified functions to a new input, and collects the results as list or data.frame. This is useful to e.g. transform columns of a data.frame or check the validity of a matrix during simulations. See the example here and in simulate_data_conditional.

The assumptions for the individual functions are:

• Each function is expected to take a single input.

• Each function is expected to output a result consistent with the other functions (i.e. same output length) to ensure that the results can be summarized as a data.frame.

Note

This function works fine without naming the input arguments, but the resulting data.frames have empty column names if that is the case. Thus, it is recommended to only pass named function arguments.

See also

data.frame, get_from_function_list, get_names_from_function_list

Examples

f <- function_list(
    v1 = function(x) x[, 1] * 2,
    v2 = function(x) x[, 2] + 10)

f(diag(2))
#>   v1 v2
#> 1  2 10
#> 2  0 11

# function_list can be used to add new columns
# naming of columns should be handled separately in such cases

f <- function_list(
    function(x) x, # return x as it is
    X1_X2 = function(x) x[, 2] + 10) # add new column

f(diag(2))
#>   X1 X2 X1_X2
#> 1  1  0    10
#> 2  0  1    11