SASxport (version 1.2.3)

read.xport: Import a SAS XPORT File

Description

Read a SAS XPORT format file and return the contained dataset(s).

Usage

read.xport(file,
           force.integer=TRUE,
           formats=NULL,
           name.chars=NULL,
           names.tolower=FALSE,
           keep=NULL,
           drop=NULL,
           as.is=0.95,
           verbose=FALSE,
           as.list=FALSE,
           include.formats=FALSE
           )

Arguments

file

Character string specifying the name or URL of a SAS XPORT file.

force.integer

Logical flag indicating whether integer-valued variables should be returned as integers (TRUE) or doubles (FALSE). Variables outside the supported integer range (.Machine$integer.max) will always be conve

formats

a data frame or list (like that created by foreign:::read.xport) containing PROC FORMAT output, if such output is not stored in the main transport file.

name.chars

Vector of additional characters permissible in variable names. By default, only the alpha and numeric characters ([A-Za-z0-9]) and periods ('.') are permitted. All other characters are converted into periods ('.').

names.tolower

Logical indicating whether variable and dataset names should be converted to lowercase (TRUE) or left uppercase (FALSE)

keep

a vector of names of SAS datasets to process. This list must include PROC FORMAT dataset if it is present for datasets to use use any of its value label formats.

drop

a vector of names of SAS datasets to ignore (original SAS upper case names)

as.is

Either a logical flag indicating whether SAS character variables should be preserved as character objects (TRUE) or factor objects (FALSE), or a fractional cutoff between 0 and 1. When a fractional cutoff is prov

verbose

Logical indicating whether progress should be printed during the data loading and conversion process.

as.list

Logical indicating whether to return a list even if the SAS xport file contains only only one dataset.

include.formats

Logical indicating whether to include SAS format information (if present) in the returned list

Value

• If only a single dataset is present (after removing PROC FORMAT data when include.formats=FALSE), the return value is a single dataframe object. Otherwise the return is a list of dataframe objects.

  Note that if include.formats=TRUE, the returned list will contain a dataframe named "FORMATS" containing any available 'PROC FORMAT' information.

Note

This code provides a subset of the functionality of the sasxport.get function in the Hmisc library.

Details

• SAS date, time, and date/time variables are converted respectively toDate, POSIX, orchronobjects
• SAS labels are stored in "label" attributes on each variable
• SAS formats are stored in "format" attributes on each variable
• SAS integer variables are stored as integers unlessforce.integerisFALSE

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

See Also

read.xport, label, sas.get, sasxport.get, Dates, DateTimeClasses, chron, lookup.xport, contents, describe

Examples

# -------
# SAS code to generate test dataset:
# -------
# libname y SASV5XPT "test2.xpt";
#
# PROC FORMAT; VALUE race 1=green 2=blue 3=purple; RUN;
# PROC FORMAT CNTLOUT=format;RUN;  * Name, e.g. 'format', unimportant;
# data test;
# LENGTH race 3 age 4;
# age=30; label age="Age at Beginning of Study";
# race=2;
# d1='3mar2002'd ;
# dt1='3mar2002 9:31:02'dt;
# t1='11:13:45't;
# output;
#
# age=31;
# race=4;
# d1='3jun2002'd ;
# dt1='3jun2002 9:42:07'dt;
# t1='11:14:13't;
# output;
# format d1 mmddyy10. dt1 datetime. t1 time. race race.;
# run;
# data z; LENGTH x3 3 x4 4 x5 5 x6 6 x7 7 x8 8;
#    DO i=1 TO 100;
#        x3=ranuni(3);
#        x4=ranuni(5);
#        x5=ranuni(7);
#        x6=ranuni(9);
#        x7=ranuni(11);
#        x8=ranuni(13);
#        output;
#        END;
#    DROP i;
#    RUN;
# PROC MEANS; RUN;
# PROC COPY IN=work OUT=y;SELECT test format z;RUN; *Creates test2.xpt;
# ------

# Read this dataset from a local file:
w <- read.xport('test2.xpt')

# Or read a copy of test2.xpt available on the web:
host <- 'http://biostat.mc.vanderbilt.edu'
path <- '/cgi-bin/viewvc.cgi/*checkout*/Hmisc/trunk/tests/test2.xpt'
url <- paste(host,path,sep="")

w <- read.xport(url)


# We can also get the dataset wrapped in a list
w <- read.xport(url, as.list=TRUE)

# And we can ask for the format information to be included as well.
w <- read.xport(url, as.list=TRUE, include.formats=TRUE)

SASxport:::assert( is.data.frame(w)==FALSE && is.list(w)==TRUE )


## The Hmisc library provides many useful functions for interacting with
## data imported from SAS via read.xport()
library(Hmisc)

describe(w$test)   # see labels, format names for dataset test
lapply(w, describe)# see descriptive stats in more detaiil for each variable

contents(w$test)   # another way to see variable attributes
lapply(w, contents)# show contents of individual items in more detail

options(digits=7)  # compare the following matrix with PROC MEANS output
t(sapply(w$z, function(x)
 c(Mean=mean(x),SD=sqrt(var(x)),Min=min(x),Max=max(x))))