read_ascii: Read ASCII datasets downloaded from the Roper Center

In ropercenter: Reproducible Data Retrieval from the Roper Center Data Archive

Read ASCII datasets downloaded from the Roper Center

Description

read_ascii helps format ASCII data files downloaded from the Roper Center.

Usage

read_ascii(
  file,
  total_cards = 1,
  var_names,
  var_cards = 1,
  var_positions,
  var_widths,
  card_pattern,
  respondent_pattern
)

Arguments

file	A path to an ASCII data file.
total_cards	For multicard files, the number of cards in the file.
var_names	A string vector of variable names.
var_cards	For multicard files, a numeric vector of the cards on which var_names are recorded.
var_positions	A numeric vector of the column positions in which var_names are recorded.
var_widths	A numeric vector of the widths used to record var_names.
card_pattern	For use when the file does not contain a line for every card for every respondent (or contains extra lines that correspond to no respondent), a regular expression that matches the file's card identifier; e.g., if the card number is stored in the last digit of each line, "\d$".
respondent_pattern	For use when the file does not contain a line for every card for every respondent (or contains extra lines that correspond to no respondent), a regular expression that matches the file's respondent identifier; e.g., if the respondent number is stored in the first four digits of each line, preceded by a space, "(?<=^\s)\d4".

Details

Many older Roper Center datasets are available only in ASCII format, which is notoriously difficult to work with. The 'read_ascii' function facilitates the process of extracting selected variables from ASCII datasets. For single-card files, one can simply identify the names, positions, and widths of the needed variables from the codebook and pass them to read_ascii's var_names, var_positions, and var_widths arguments. Multicard datasets are more complicated. In the best case, the file contains one line per card per respondent; then, the user can extract the needed variables by adding only the var_cards and total_cards arguments. When this condition is violated—there is not a line for every card for every respondent, or there are extra lines—the function will throw an error and request the user specify the additional arguments card_pattern and respondent_pattern.

Value

A data frame containing any variables specified in the var_names argument, plus a numeric respondent identifier and as many string card variables (card1, card2, ...) as specified by the total_cards argument.

Examples

## Not run: 
# a single-card file
roper_download("USAIPO1982-1197G", # Gallup Poll for June 25-28, 1982
               download_dir = tempdir())  # remember to specify a directory for your download
                      
gallup1982 <- read_ascii(file = file.path(tempdir(), "USAIPO1982-1197G",
                                          "1197.dat"),
                         var_names = c("q09j", "weight"),
                         var_positions = c(38, 1),
                         var_widths = c(1, 1))
   
# a multi-card file, with extra lines that make the card_pattern and
  respondent_pattern arguments necessary
roper_download("USAIPOCNUS1996-9603008", # Gallup/CNN/USA Today Poll: Politics/1996 Election
               download_dir = tempdir())  # remember to specify a directory for your download

gallup1996 <- read_ascii(file = file.path(tempdir(), "USAIPOCNUS1996-9603008",
                                          "a9603008.dat"),
                         var_names = c("q43a", "q44", "weight"),
                         var_cards = c(6, 6, 1),
                         var_positions = c(62, 64, 13),
                         var_widths = c(1, 1, 3),
                         total_cards = 7,
                         card_pattern = "(?<=^.{10})\\d", 
                                        # (a digit, preceded by the start of the line
                                        # and ten other characters)
                         respondent_pattern = "(?<=^\\s{2})\\d{4}")
                                       # (# four digits, preceded by the start of the line
                                       # and two whitespace characters)

## End(Not run)

ropercenter documentation built on July 9, 2023, 7:24 p.m.