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SAS Scripting Wrapper for Analytics Transfer (SWAT) for R

SWAT is an R package that enables you to interface with SAS Cloud Analytics Services (CAS), the in-memory server that is the centerpiece of the SAS Viya platform. Using the SWAT package, you can write an R program that connects to a CAS server, analyze large in-memory data sets, and then work with the results of the data analysis using familiar data-wrangling techniques in R.

This package provides facilities for starting a CAS session and running actions in CAS--such as classifying data with a decision tree or modeling with linear regression. Data processing is performed by CAS, which can scale from a single-machine server to distributed servers that run on multiple hosts and perform massively parallel processing.

Installation and Configuration

Requirements

To use the SWAT package for R, the client machine that runs R must meet the following requirements:

  • Use 64-bit Linux or 64-bit Windows.
  • Use a 64-bit version of R.
  • Use R 3.1.0 or later.
  • Install the dplyr, httr and jsonlite packages. These packages have additional dependencies that are automatically installed from CRAN when you run install.packages().

Installation

The SWAT package for R is available from SAS as a tar.gz file. You can download releases from https://github.com/sassoftware/R-swat/releases.

After you download the package, you can install the package with a command that is similar to the following:

R CMD INSTALL R-swat-X.X.X-platform.tar.gz

You can also install from within R directly using a URL.

# Make sure prerequisites are installed
> install.packages('dplyr')
> install.packages('httr')
> install.packages('jsonlite')

> install.packages('https://github.com/sassoftware/R-swat/releases/download/vX.X.X/R-swat-X.X.X-platform.tar.gz',
                   repos=NULL, type='file')

If you are running on a platform that does not have an associated installer, you should install the source code tar.gz. These platforms will be limited to using the CAS REST interface only.

> install.packages('https://github.com/sassoftware/R-swat/archive/vX.X.X.tar.gz', 
                   repos=NULL, type='file')

Connecting to CAS

Authinfo File

Using a .authinfo file is not required to use the package, but is recommended. When you enter your credentials (user ID and password) in a .authinfo file and secure the permissions, you can avoid specifying those credentials in programs.

Throughout the documentation, it is assumed that you have a .authinfo file. The following statement connects R to CAS and supplies the credentials from the .authinfo file:

conn <- swat::CAS('cloud.example.com', 8777, protocol='http')

If you do not use a .authinfo file, then you must connect with a statement like the following:

conn <- swat::CAS('cloud.example.com', 8777, protocol='http', username='sasdemo', password='!s3cret')

Binary and REST Communication

Communication between R and CAS can be performed in a binary format with proprietary C libraries, or over HTTP to a REST interface on the server. The C libraries (and therefore binary communication) are supported for 64-bit Linux or Windows only. Connections to CAS that use binary communication are similar to the following example:

conn <- swat::CAS('cloud.example.com', 5570)

Example

> library(swat)

# Connect to CAS
> conn <- swat::CAS('cloud.example.com', 8777)

# Load Iris data set into in-memory table
> iris.ct <- as.casTable(conn, iris)

# Use basic R functions on CAS table
> min(iris.ct$Sepal.Length)
[1] 4.3

> max(iris.ct$Sepal.Length)
[1] 7.9

> mean(iris.ct$Sepal.Length)
[1] 5.843333

# Call CAS actions on the table
> out <- cas.simple.summary(iris.ct)
> out
$Summary
        Column Min Max   N NMiss     Mean   Sum       Std     StdErr       Var
1 Sepal.Length 4.3 7.9 150     0 5.843333 876.5 0.8280661 0.06761132 0.6856935
2  Sepal.Width 2.0 4.4 150     0 3.057333 458.6 0.4358663 0.03558833 0.1899794
3 Petal.Length 1.0 6.9 150     0 3.758000 563.7 1.7652982 0.14413600 3.1162779
4  Petal.Width 0.1 2.5 150     0 1.199333 179.9 0.7622377 0.06223645 0.5810063
      USS       CSS       CV   TValue         ProbT
1 5223.85 102.16833 14.17113 86.42537 3.331256e-129
2 1430.40  28.30693 14.25642 85.90830 8.004458e-129
3 2582.71 464.32540 46.97441 26.07260  2.166017e-57
4  302.33  86.56993 63.55511 19.27060  2.659021e-42

# Explore results
> out$Summary[c('Column', 'Min', 'Max')]

If you get an error message about the TCP/IP negClientSSL support routine, you likely have an issue with your SSL certificate configuration. See the Encryption documentation (the R configuration is the same as the Python client) for more information.