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Read and write SAS transport files

Source: R/haven-sas.R
read_xpt.Rd

The SAS transport format is a open format, as is required for submission of the data to the FDA.

Usage

read_xpt(
  file,
  col_select = NULL,
  skip = 0,
  n_max = Inf,
  .name_repair = "unique"
)

write_xpt(
  data,
  path,
  version = 8,
  name = NULL,
  label = attr(data, "label"),
  adjust_tz = TRUE
)

Arguments

file

Either a path to a file, a connection, or literal data (either a single string or a raw vector).

Files ending in .gz, .bz2, .xz, or .zip will be automatically uncompressed. Files starting with http://, https://, ftp://, or ftps:// will be automatically downloaded. Remote gz files can also be automatically downloaded and decompressed.

Literal data is most useful for examples and tests. To be recognised as literal data, the input must be either wrapped with I(), be a string containing at least one new line, or be a vector containing at least one string with a new line.

Using a value of clipboard() will read from the system clipboard.

col_select

One or more selection expressions, like in dplyr::select(). Use c() or list() to use more than one expression. See ?dplyr::select for details on available selection options. Only the specified columns will be read from data_file.

skip

Number of lines to skip before reading data.

n_max

Maximum number of lines to read.

.name_repair

Treatment of problematic column names:

  • "minimal": No name repair or checks, beyond basic existence,

  • "unique": Make sure names are unique and not empty,

  • "check_unique": (default value), no name repair, but check they are unique,

  • "universal": Make the names unique and syntactic

  • a function: apply custom name repair (e.g., .name_repair = make.names for names in the style of base R).

  • A purrr-style anonymous function, see rlang::as_function()

This argument is passed on as repair to vctrs::vec_as_names(). See there for more details on these terms and the strategies used to enforce them.

data

Data frame to write.

path

Path to a file where the data will be written.

version

Version of transport file specification to use: either 5 or 8.

name

Member name to record in file. Defaults to file name sans extension. Must be <= 8 characters for version 5, and <= 32 characters for version 8.

label

Dataset label to use, or NULL. Defaults to the value stored in the "label" attribute of data.

Note that although SAS itself supports dataset labels up to 256 characters long, dataset labels in SAS transport files must be <= 40 characters.

adjust_tz

Stata, SPSS and SAS do not have a concept of time zone, and all date-time variables are treated as UTC. adjust_tz controls how the timezone of date-time values is treated when writing.

  • If TRUE (the default) the timezone of date-time values is ignored, and they will display the same in R and Stata/SPSS/SAS, e.g. "2010-01-01 09:00:00 NZDT" will be written as "2010-01-01 09:00:00". Note that this changes the underlying numeric data, so use caution if preserving between-time-point differences is critical.

  • If FALSE, date-time values are written as the corresponding UTC value, e.g. "2010-01-01 09:00:00 NZDT" will be written as "2009-12-31 20:00:00".

Value

A tibble, data frame variant with nice defaults.

Variable labels are stored in the "label" attribute of each variable. It is not printed on the console, but the RStudio viewer will show it.

If a dataset label is defined, it will be stored in the "label" attribute of the tibble.

write_xpt() returns the input data invisibly.

Examples

tmp <- tempfile(fileext = ".xpt")
write_xpt(mtcars, tmp)
read_xpt(tmp)
#> # A tibble: 32 × 11
#>      mpg   cyl  disp    hp  drat    wt  qsec    vs    am  gear  carb
#>    <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#>  1  21       6  160    110  3.9   2.62  16.5     0     1     4     4
#>  2  21       6  160    110  3.9   2.88  17.0     0     1     4     4
#>  3  22.8     4  108     93  3.85  2.32  18.6     1     1     4     1
#>  4  21.4     6  258    110  3.08  3.22  19.4     1     0     3     1
#>  5  18.7     8  360    175  3.15  3.44  17.0     0     0     3     2
#>  6  18.1     6  225    105  2.76  3.46  20.2     1     0     3     1
#>  7  14.3     8  360    245  3.21  3.57  15.8     0     0     3     4
#>  8  24.4     4  147.    62  3.69  3.19  20       1     0     4     2
#>  9  22.8     4  141.    95  3.92  3.15  22.9     1     0     4     2
#> 10  19.2     6  168.   123  3.92  3.44  18.3     1     0     4     4
#> # ℹ 22 more rows