R/csvkit.schema.R

In mrdwab/StataDCTutils: Converts Stata dictionary files to formats more meaningful for R users

#'Convert a parsed dictionary file to a csvkit schema file
#'
#'After parsing a \code{.dct} dictionary file with the \code{\link{dct.parser}}
#'function, it may be useful to convert that file to a schema that can be used
#'by \emph{csvkit}, a useufl Pyton tool for working with csv files. In
#'particular, this creates a schema that allows you to convert a fixed width
#'format file to a csv file.
#'
#'This function will write a csv file to your current working directory. It
#'takes the name of the original parsed dictionary file appended with .csv by
#'default (which is stored as an attribute of the \code{data.frame} created
#'during the dictionary parsing step). If that attribute is not present, it
#'prompts the user for a file name, which should be provided \emph{not quoted}.
#'
#'@param x Your input \code{data.frame}. Must include at least the following
#'information in separate columns: the variable names, the starting position of
#'the variable, and the length of the variable in the fixed width file.
#'@param columns.to.match By default, if the input file is the output of
#'\code{\link{dct.parser}}, the values for this argument do not need to be
#'specified. If you are using your own \code{data.frame}, specify which columns
#'contain the (1) variable name, (2) the starting position, and (3) the width
#'of the variable.
#'@author Ananda Mahto
#'@references csvkit's \code{in2csv} documentation:
#'\url{https://csvkit.readthedocs.org/en/latest/scripts/in2csv.html}
#'@examples
#'
#'## Read an example dictionary file
#'data(sampleDctData)
#'## Write the data to a dictionary file
#'currentdir <- getwd()
#'setwd(tempdir())
#'writeLines(sipp84fp_dct, "sipp84fp.dct")
#'sipp84_R_dict <- dct.parser("sipp84fp.dct")
#'list.files(pattern=".dat|.dct|.csv")
#'csvkit.schema(sipp84_R_dict)
#'list.files(pattern=".dat|.dct|.csv")
#'setwd(currentdir)
#'
csvkit.schema <- function(x, columns.to.match = NULL) {
  if (is.null(columns.to.match)) {
    columns.to.match <- c("ColName", "StartPos", "ColWidth")
    if(!all(columns.to.match %in% names(x))) {
      stop("Please specify which column names match 'variable name',
           'starting position', and 'variable width'")
    }
  }
  mycsvkit <- x[columns.to.match]
  names(mycsvkit) <- c("column", "start", "length")
  if (is.null(attributes(x)$original.dictionary[2])) {
    outname <- readline(prompt = "Please specify the output filename: ")
  } else {
    outname <- paste(attributes(x)$original.dictionary[2], 
                     ".csv", sep = "")
  }
  write.csv(mycsvkit, 
            file = outname, row.names = FALSE)
}