R integration

The standard library contains nodes that allow to run R scripts. This means that you will need to install a distribution of R.

Setting up R

You have the option to either select an existing R environment, or let JIPipe install a new R environment into a folder (only available on Windows).

To setup Python, navigate to Project > Application settings > Extensions > R integration. There you will find a setting R environment that, by default, is not set up.

If you want to select an existing R environment or let JIPipe handle the installation for you, choose the Select/Install button and select the appropriate operation. Follow the instructions provided in the newly opened window.

You can also edit existing R environments by selecting the Edit button to, for example, setup environment variables or change command line parameters.

Included nodes

You can find the R scripting nodes in the Miscellaneous menu. You can find algorithms equivalent to following Java standard algorithms:

Both nodes share a similar R API to communicate with JIPipe - the difference being how many data items can be processed in each iteration. All nodes repeat the script for each data batch (or at least once if there is none). Data batches organize the data of various input slots into one bundle that should be processed.

Data I/O

As R is run in a separate environment, the data is communicated by writing it to the hard drive from one process and reading it back inside the other process. Currently, the nodes are designed for following data types:

Other data types are supported, although there are no predefined utility functions to load/save them for now.

Loading results tables

Result tables can be loaded via the JIPipe.GetInputAsDataFrame(slot, row=0) function. The slot parameter must be identical to the name of the input slot. The row parameter indicates which item of the current data batch should be returned. Please note that row can only be zero if you are using R script (iterating).

If you have multiple rows, you can find their count in JIPipe.InputSlotRowCounts

for( i in 1:JIPipe.InputSlotRowCounts$Tables) {
  # Note that the row has zero-based indices
  table <- JIPipe.GetInputAsDataFrame(slot="Tables", row=i-1)
}

Writing result tables

Result tables can be written via a function JIPipe.AddOutputDataFrame(data, slot, annotations=list()). This will add a new result table to the specified output. Please note, that you can add multiple outputs.

The provided data must be of a type compatible with write.csv, like data.frame.

Optionally, you can provide a list of annotations that should be added to the specified output data as list of named strings.

library(datasets)
JIPipe.AddOutputDataFrame(iris, "Tables", annotations=list("data set"="Iris"))

Writing plots or other images

As R does not have a dedicated data type for images, the JIPipe API will only provide means to generate a valid output file name. For this, two methods JIPipe.AddOutputPNGImagePath(data, slot, annotations=list()) and JIPipe.AddOutputTIFFImagePath(data, slot, annotations=list()) are available that produce a path for PNG or TIFF files respectively.

library(datasets)

# Generate the output file name
png.file.name <- JIPipe.AddOutputPNGImagePath(slot="Plot")

# Use standard R functions. Write into this file.
png(png.file.name, width = 800, height = 600)
plot(iris$Petal.Length, iris$Petal.Width, pch=21, bg=c("red","green3","blue")[unclass(iris$Species)], main="Edgar Anderson's Iris Data")
dev.off()

# JIPipe will automatically load the data

Reading and writing other data types

Currently, only reading and writing of tables, as well as writing of image data is supported via convience functions. The node supports all other JIPipe data types, although import and export must be written via custom functions.

JIPipe provides the input of each data item via a dedicated folder that contains all files related to this data. Use JIPipe.GetInputFolder(slot, row=0) get obtain the path to this folder.

Outputs are also expected to be provided in standardized JIPipe format. Use JIPipe.AddOutputFolder(slot, annotations=list()) to obtain a valid path to such a folder and register the output.

Script parameters

Each node provides means to define R variables inside the JIPipe environment via custom parameters. Each parameter value is passed as variable into R - the name of the variable being determined by the unique ID of the parameter.

Independent of the compatibility of a parameter’s unique key, all variables are also provided as named list entries in JIPipe.Variables.