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Parse SAS DATALINES/CARDS blocks into a data.frame

Source: R/parseSASDatalines.R
parseSASDatalines.Rd

A parser for simple SAS dataline command texts. A data.frame is being built with the columnnames listed in the input section.

Usage

parseSASDatalines(x, validateNames = FALSE)

Arguments

x

a single character string containing a SAS DATA step with a DATALINES, CARDS, or CARDS4 block.

validateNames

logical. If TRUE (default FALSE), emits a warning when the dataset name violates SAS naming rules.

Value

a data.frame with column names taken from the INPUT statement. The attribute sas_dataset_name carries the DATA step name. For DATA _NULL_ the data is still parsed and returned; the caller decides what to do with it (matching SAS semantics). SAS missing-value markers (.) are converted to NA.

Details

The SAS function DATA is designed for quickly creating a dataset from scratch. The whole step normally consists out of the DATA part defining the name of the dataset, an INPUT line declaring the variables and a DATALINES command followed by the values.
The default delimiter used to separate the different variables is a space (thus each variable should be one word). The $ after the variable name indicates that the variable preceding contain character values and not numeric values. Without specific instructions, SAS assumes that variables are numeric. The function will fail, if it encounters a character in the place of an expected numeric value.
Each new row in datalines will create a corresponding unique row in the dataset. Notice that a ; is not needed after every row, rather it is included at the end of the entire data step.

More complex command structures, i.e. other delimiters (dlm), in the INPUT-section are not (yet) supported.

Only free-format (list) input is supported. The following SAS features are intentionally rejected with an informative error:

  • Column pointers (@, @)

  • Column input (e.g. var 1-10)

  • Formatted input (:)

Character values must not contain spaces or quotes; scan-based parsing splits on whitespace and does not handle quoted strings.

See also

Other file.io: pdfManual(), peekFile(), readDownload()

Examples

sas_code <- "
  data mydata;
    input name $ age score;
  datalines;
  Alice 30 95.5
  Bob   25 88.0
  ;
"
df <- parseSASDatalines(sas_code)