SASxport - Read and Write SAS XPORT Files

This package provides functions for reading, listing the contents of, and writing SAS xport format files. The functions support reading and writing of either individual data frames or sets of data frames. Further, a mechanism has been provided for customizing how variables of different data types are stored.

Installation

From CRAN

install.packages("SASxport")

From GitHub

devtools::install_github("warnes/SASxport")

Usage

library(SASxport)

Writing SAS XPORT files

write.xport writes one or more data frames into a SAS XPORT format library file.

The function creates a SAS XPORT data file (see reference) from one or more data frames. This file format imposes a number of constraints:

• Data set and variable names are truncated to 8 characters and converted to upper case. All characters outside of the set A-Z, 0-9, and '_' are converted to '_'.
• Character variables are stored as characters.
• If autogen.formats = TRUE (the default), factor variables are stored as numeric with an appropriate SAS format specification. If autogen.formats = FALSE, factor variables are stored as characters.
• All numeric variables are stored as double-precision floating point values utilizing the IBM mainframe double precision floating point format (see the reference).
• Date and time variables are either converted to number of days since 1960-01-01 (date only), or number of seconds since 1960-01-01:00:00:00 GMT (date-time variables).
• Missing values are converted to the standard SAS missing value .

The SAS XPORT format allows each dataset to have a label and a type (set via the label and SAStype functions). In addition, each variable may have a corresponding label, display format, and input format. To set these values, add the attribute label, SASformat, or SASiformat to individual data frame. These attributes may be set using the label, SASformat, and SASiformat functions. (See examples in the package.)

The actual translation of R objects to objects appropriate for SAS is handled by the toSAS generic and associated methods, which can be (re)defined by the user to provide fine-grained control.

Reading SAS XPORT files

read.xport reads a file as a SAS XPORT format library and returns a list of data frames:

• SAS date, time, and date/time variables are converted respectively to Date, POSIX, or chron objects.
• SAS labels are stored in label attributes on each variable, and are accessible using the label function.
• SAS formats are stored in SASformat attributes on each variable, and are accessible using SASformat.
• SAS iformats are stored in SASiformat attributes on each variable, and are accessible using SASiformat.
• SAS integer variables are stored as integers unless force.integer is FALSE.

If the file includes the output of PROC FORMAT CNTLOUT=, variables having customized label formats will be converted to factor objects with appropriate labels.

If a datasets in the original file has a label or type, these will be stored in the corresponding label and SAStype attributes, which can be accessed by the label and SAStype functions.

License

GPL 2.1 © Gregory R. Warnes, United States Government, Frank E. Harrell, Jr., Douglas M. Bates, Mango Solutions