withinFun: withinFun, applying functions on clustered data structure.

In kthorstmann/horst: Functions for the processing of questionnaire data

Description

The function applies a function on a nested data structure. The function applied can be any type of function with one argument. The function uses the function map and the package stringr. For how to enter the function, see details.

Usage

withinFun(data, id.var, fun, return.data.frame = FALSE, var.spec = NULL,
  fun.spec = NULL)

Arguments

data	An object, a data frame or a list.
id.var	The variable in which the scores are clustered, usually an ID variable. Must be a character string.
fun	The function to apply on the scores within the ID variable. Must be entered as a character string. See details for further information.
return.data.frame	Logical, should a data frame be returned, matching the results as a variable on the same level as the ID variable? Default is to FALSE.
var.spec	Not implemented yet. If a variable cannot be detected, it can be specified here. Default is to NULL.
fun.spec	Not implemented yet. If a function cannot be detected, it can be specified here. Default is to NULL.

Details

Entering a function. The argument fun needs to be a character string. It needs to have the following struncture fun = "function(variable), arguments to function".

• variable the function to apply, such as mean, length, sd.

• function the variable to apply the function on. This variable must not be enterd as a string, just as plain text.

• further arguments to function further arguments that are passed to the function, such as na.rm = TRUE for mean.

The results can be either of the following, depending on return.data.frame

• return.data.frame = TRUE This returns the complete data frame with the new variable included. The results of the function and the input data are merged by the id.var.The new variable has the name variable_function.

• return.data.frame = FALSE This returns a list with each entry being an id.var. This result can be easily used for further analyses.

Value

Returns a data frame or a list with the results of the function, fun. Can be either a list or a data frame, depending on the value of return.data.frame.

Examples

## make sample data frame
variable_1 <- rnorm(100, 1)
variable_2 <- rnorm(100, 2)
id <- sample(letters[1:5], 100, replace = TRUE)
data <- data.frame(id, variable_1, variable_2)

## run function, get length of each ID variable on "variable1", returning a data frame
withinFun(data, id.var="id", "length(variable1)", return.data.frame = TRUE)

# get the mean of each ID variable on "variable1", returning a list with the entries only
withinFun(data, id.var="id", "mean(variable1, na.rm =TRUE)")

kthorstmann/horst documentation built on May 20, 2019, 7:04 p.m.