install.packages("haven")

haven 1.0.0 is a major release, and indicates that haven is now largely feature complete and has been tested on many real world datasets. There are four major changes in this version of haven:

  1. Improvements to the underlying ReadStat library
  2. Better handling of “special” missing values
  3. Improved date/time support
  4. Support for other file metadata.

There were also a whole bunch of other minor improvements and bug fixes: you can see the complete list in the release notes.

ReadStat

Haven builds on top of the ReadStat C library by Evan Miller. This version of haven includes many improvements thanks to Evan’s hard work on ReadStat:

  • Can read binary/Ross compressed SAS files.
  • Support for reading and writing Stata 14 data files.
  • New write_sas() allows you to write data frames out to sas7bdat files. This is still somewhat experimental.
  • read_por() now actually works.
  • Many other bug fixes and minor improvements.

Missing values

haven 1.0.0 includes comprehensive support for the “special” types of missing values found in SAS, SPSS, and Stata. All three tools provide a global “system missing value”, displayed as .. This is roughly equivalent to R’s NA, although neither Stata nor SAS propagate missingness in numeric comparisons (SAS treats the missing value as the smallest possible number and Stata treats it as the largest possible number).

Each tool also provides a mechanism for recording multiple types of missingness:

  • Stata has “extended” missing values, .A through .Z.
  • SAS has “special” missing values, .A through .Z plus ._.
  • SPSS has per-column “user” missing values. Each column can declare up to three distinct values or a range of values (plus one distinct value) that should be treated as missing.

Stata and SAS only support tagged missing values for numeric columns. SPSS supports up to three distinct values for character columns. Generally, operations involving a user-missing type return a system missing value.

Haven models these missing values in two different ways:

  • For SAS and Stata, haven provides tagged_na() which extend R’s regular NA to add a single character label.
  • For SPSS, haven provides labelled_spss() that also models user defined values and ranges.

Use zap_missing() if you just want to convert to R’s regular NAs.

You can get more details in the semantics vignette.

Date/times

Support for date/times has substantially improved:

  • read_dta() now recognises “%d” and custom date types.
  • read_sav() now correctly recognises EDATE and JDATE formats as dates. Variables with format DATE, ADATE, EDATE, JDATE or SDATE are imported as Date variables instead of POSIXct.
  • write_dta() and write_sav() support writing date/times.
  • Support for hms() has been moved into the hms package. Time varibles now have class c("hms", "difftime") and a unitsattribute with value “secs”.

Other metadata

Haven is slowly adding support for other types of metadata:

  • Variable formats can be read and written. Similarly to to variable labels, formats are stored as an attribute on the vector. Use zap_formats() if you want to remove these attributes.
  • Added support for reading file “label” and “notes”. These are not currently printed, but are stored in the attributes if you need to access them.