Categories
Format Specific
Integrations
Rasters

RCaller

Executes an R script that has the ability to access feature data from a temporary R data frame.

How does it work?

Input data is set up in the form of tables that will become R data frames. R data frames are tables similar to those of a relational database that support columns of varying types. More information on R data frames can be found at:

https://www.r-tutor.com/r-introduction/data-frame

This transformer requires that the system has R and the sqldf package installed in order to run. See Installing R in the Usage Notes section.

Any number of input data frames can be created, and each will be assigned an input port. Any features can be routed to that input port as long as they supply values for each column defined for the table. The R Script can involve any and all data frames and columns defined in the input. Output is taken from the fmeOutput data frame that the user can populate with the results of statistical analysis on any of the input tables.

Any number of input ports can be created either by connecting to the Connect Input port or by editing the transformer properties and manually adding new inputs or by importing port definitions from existing feature types. Once imported the table definitions will not automatically change as their source changes, in the event an attribute name is changed upstream the name of the corresponding table column will need to be manually adjusted in the table parameters. Users will need to manually expose the output attributes which will be imported from the column names of the fmeOutput data frame at runtime.

The success of the translation relies on the user supplying a valid R Script that adheres to proper R syntax. A guide on the R Language is listed below:

https://cran.r-project.org/doc/manuals/r-release/R-lang.html

To learn more about how to use R and to get ideas for different types of statistical analysis that may be possible, the following links are recommended:

https://www.r-bloggers.com/2015/12/how-to-learn-r-2/

https://www.r-tutor.com/r-introduction

Examples

Usage Notes

Installing R

To use this transformer, you must install both R and the sqldf package. Using raster objects additionally requires the raster package.

Troubleshooting Tips

Specifying the R Interpreter

FME will try its best to find R as installed on your system; however, if R is installed in a non-default location, or you have multiple R interpreters installed, it may be necessary to specify the R Interpreter Path under Tools > FME Options > Translation > R Interpreter

Configuration

Parameters

Editing Transformer Parameters

Transformer parameters can be set by directly entering values, using expressions, or referencing other elements in the workspace such as attribute values or user parameters. Various editors and context menus are available to assist. To see what is available, click beside the applicable parameter.

For more information, see Transformer Parameter Menu Options.

FME Community

The FME Community has a wealth of FME knowledge with over 20,000 active members worldwide. Get help with FME, share knowledge, and connect with users globally.

Search for all results about the RCaller on the FME Community.