[R] Read files with specific extensions in the directory as dataframes

read_dir.R

# read_dir

# description
#
# read files with specific extensions in the directory as dataframes

# args
#
# directory     : directory should not end with "\"
# extensions    : extensions of the files to be selected as a character
#                 vector. Default: c("csv")
# read_function : function as a name or as a string. Deafult: "read.csv"
# env           : environment where the dataframes are loaded to
#                 Default: parent.frame()
# ...           : arguments passed to read_function

# Dependencies
#
# >= R 3.0
# assertthat
# tools

# author
# Srikanth KS (talegari)
# gist.github.com/talegari

read_dir = function(directory
                    , extensions    = c("csv")
                    , read_function = "read.csv"
                    , env           = parent.frame()
                    , ...){
  
    stopifnot(require("assertthat"))
    assert_that(require("tools"))
    assert_that(file_test("-d", directory))
    assert_that(is.readable(directory))
    assert_that(class(extensions) == "character")
    assert_that(is.function(match.fun(read_function)))

    args = list(...)
    filenames = list_files_with_exts(directory, extensions)
    for(filename in filenames){
        assign(file_path_sans_ext(basename(filename))
               , do.call(read_function
                         , c(filename, args)
               )
               , envir = env)
    }
    return(invisible(TRUE))
}