How to input an array in R script running inside QGIS

Question

I am using QGIS 2.18.21 and running an R script which needs various files as inputs. The number of files to be inputted is also entered by user. I am thinking of taking the input of all file paths in an array. I am aware that in QGIS, we must specify the type of input at the beginning of script using ##. I have tried the following:

## file_arr = array
## file_array = list

but I got strange errors. The script didn't even run at all. For example, with a script as simple as the following:

##arr=array
print(arr)

I got the error: enter image description here

and on clicking the View mesage log, I got the following: enter image description here

Now, first of all I have no idea why is this a Python error since I am running a R script, and secondly there is no proper documentation of how to specify the input of different R data types in QGIS. Please help me out to take an array as input.

Answer 1

1. first of all I have no idea why is this a Python error since I am running a R script

Processing is a Python module that uses subprocess to run R scripts, and so, it's a Python error

2. there is no proper documentation of how to specify the input of different R data types

You can only use the parameter types that are supported in R processing scripts (Use R scripts in Processing) and those of Writing new Processing algorithms as python scripts (look at Python headers in R scripts for QGIS)

##arr=string
print(arr)

Examine the example scripts of QGIS-Processing/rscripts/ for example