qol (version 1.2.0)

convert_arguments: Convert Function Arguments to Character Vector

Description

args_to_char(): Converts any argument passed as a single character or symbol as well as character vectors or vector of symbols back as character vector.

dots_to_char(): When you define a function and want the user to be able to pass variable names without the need to have them stored in a vector c() or list() beforehand and without putting the names into quotation marks, you can convert this variable list passed as ... into a character vector.

Note: If the user passes a list of characters it is returned as given.

get_origin_as_char() is a wrapper that allows to retrieve the original contents of the provided variable, whether called directly or nested in multiple function calls, as a character vector.

Usage

args_to_char(argument)
dots_to_char(...)
get_origin_as_char(original, substituted)

Value

Returns a character vector.

Arguments

argument

Function argument to convert.

...

Used for variable names listed in ... without the need to put them in c() or list().

original

The data frame which contains the columns to be checked.

substituted

The grouping variables which potentially form unique combinations.

Examples

# Example function with function parameter
print_vnames <- function(parameter){
    var_names <- args_to_char(substitute(parameter))
    print(var_names)
}

print_vnames(age)
print_vnames("age")
print_vnames(c(age, sex, income, weight))
print_vnames(c("age", "sex", "income", "weight"))

# You can also pass in a character vector, if you have stored variable names elsewhere
var_names <- c("age", "sex", "income", "weight")
print_vnames(var_names)

# If you plan to use the function within other functions, better use get_origin_as_char()
print_vnames <- function(parameter){
    var_names <- get_origin_as_char(parameter, substitute(parameter))
    print(var_names)
}

another_function <- function(parameter){
    print_vnames(parameter)
}

another_function("age")
another_function(c("age", "sex", "income", "weight"))

# Example function with ellipsis
print_vnames <- function(...){
    var_names <- dots_to_char(...)
    print(var_names)
}

print_vnames(age)
print_vnames("age")
print_vnames(age, sex, income, weight)
print_vnames("age", "sex", "income", "weight")

# You can also pass in a character vector, if you have stored variable names elsewhere
var_names <- c("age", "sex", "income", "weight")
print_vnames(var_names)