How to run a specific function in Python file via R in Shiny?

Question

I'm using source_python() function to run a Python Script via user interface of R Shiny. Code is running properly and I'm successful in it. But I want to run a function named function2() which is in Task3.py. Can I do this? If yes then how can I do this? I just want to execute function2(). I don't want function1() and function3() to run. I'm doing this by using following lines and syntax which I found by Googling. I'm unsuccessful in running just function2() by following below link. The link that I followed is:

https://rstudio.github.io/reticulate/articles/calling_python.html

server.R:

library(reticulate)
observeEvent(input$action,{
    py_run_file("applications/Task3.py")
    function2()
  })

Task3.py:

def main(argv):
   function1()
   ....
   function2()
   ....
   function3()
   ....
if __name__ == "__main__":
    try:
        k=sys.exit(main(sys.argv))
    except (ValueError, IOError) as e:
        sys.exit(e)

The first example in the linked tutorial does exactly what you want. Just import your module instead of OS. — Mad Physicist
– Mad Physicist, Commented Jul 22, 2018 at 13:14

Mad Physicist · Accepted Answer · 2018-07-22 13:27:45Z

2

To call a single function from a python module, you need to import the module as an object and run the function from it rather than executing the module as a script.

The tutorial you linked starts with how to do exactly that. Instead of py_run_file, you'll want to use import:

library(reticulate)
observeEvent(input$action,{
    task3 <- import("Task3")
    task3$function2()
})

You may have to switch to the applications directory or add it to your PYTHONPATH for the import to work properly.

answered Jul 22, 2018 at 13:27

Mad Physicist

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4 Comments

Knowledge Seeker Over a year ago

Sir, I'm getting this error by doing this: Warning: Error in py_get_attr_impl: AttributeError: module 'Task3' has no attribute 'function2()'

Mad Physicist Over a year ago

That's because you don't define or import function2 in your module. You need to fix your python code.

Angelo Over a year ago

Is it possible also to pass parameters to the function call ?

Mad Physicist Over a year ago

@Angelo. I would assume so. I've never actually used R :)

Gabriel Ascui · Accepted Answer · 2023-10-05 19:44:46Z

0

You can try using source_python() instead of py_run_file. This will add a function to your .Globalenv which the python function in task3.py.

library(reticulate)
observeEvent(input$action,{
    source_python("task3.py")
    function2()
})

edited Oct 5, 2023 at 19:44

answered Oct 5, 2023 at 19:44

Gabriel Ascui

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