如何通过 R package 中的字符串调用内部数据集

Question

I have included a few internal data sets during building a local R package such as data_abc, data_cdj, ..., data_mnp . Then I am attempting to write a function to call one of these datasets depending on the user's input argument p which will abc , cdj , ... , mnp such as:

get_data <- function(p) {
       use_data <- paste0('data_', 'p')
       ...
       return(use_data)
}

Since use_data <- paste0('data_', 'p') is a string, my question is how to make the function return the internal data such as data_mnp if p = 'mnp' .

Answer 1

I think this is how you need to do it, but I'd love to be corrected.

get_data <- function(p) {

    data_name = paste0( "data_", p )


    # check first that it exists in your package:
    ns <- getNamespace("your.package.name")
    if(!exists(data_name, where=ns, inherits=FALSE)) {
        stop( "a data set with suffix ", p, " does not exist!")
    }

    return( get( data_name, where=ns, inherits=FALSE ) )

}