xlwings with R and Julia

While xlwings is a pure Python package, there are cross-language packages that allow for a relative straightforward use from/with other languages. This means, however, that you’ll always need to have Python with xlwings installed in addition to R or Julia. We recommend the Anaconda distribution, see also Installation.

R

The R instructions are for Windows, but things work accordingly on Mac except that calling the R functions as User Defined Functions is not supported at the moment (but RunPython works, see Call Python with “RunPython”).

Setup:

  • Install R and Python
  • Add R_HOME environment variable to base directory of installation, .e.g C:\Program Files\R\R-x.x.x
  • Add R_USER environment variable to user folder, e.g. C:\Users\<user>
  • Add C:\Program Files\R\R-x.x.x\bin to PATH
  • Restart Windows because of the environment variables (!)

Simple functions with R

Original R function that we want to access from Excel (saved in r_file.R):

myfunction <- function(x, y){
    return(x * y)
}

Python wrapper code:

import xlwings as xw
import rpy2.robjects as robjects
# you might want to use some relative path or place the file in R's current working dir
robjects.r.source(r"C:\path\to\r_file.R")

@xw.func
def myfunction(x, y):
    myfunc = robjects.r['myfunction']
    return tuple(myfunc(x, y))

After importing this function (see: UDF Tutorial), it will be available as UDF from Excel.

Array functions with R

Original R function that we want to access from Excel (saved in r_file.R):

array_function <- function(m1, m2){
  # Matrix multiplication
  return(m1 %*% m2)
}

Python wrapper code:

import xlwings as xw
import numpy as np
import rpy2.robjects as robjects
from rpy2.robjects import numpy2ri

robjects.r.source(r"C:\path\to\r_file.R")
numpy2ri.activate()

@xw.func
@xw.arg("x", np.array, ndim=2)
@xw.arg("y", np.array, ndim=2)
def array_function(x, y):
    array_func = robjects.r['array_function']
    return np.array(array_func(x, y))

After importing this function (see: UDF Tutorial), it will be available as UDF from Excel.

Julia

Setup:

  • Install Julia and Python
  • Run Pkg.add("PyCall") from an interactive Julia interpreter

xlwings can then be called from Julia with the following syntax (the colons take care of automatic type conversion):

julia> using PyCall
julia> @pyimport xlwings as xw

julia> xw.Book()
PyObject <Book [Workbook1]>

julia> xw.Range("A1")[:value] = "Hello World"
julia> xw.Range("A1")[:value]
"Hello World"