Error when trying to use Python Gekko in R via reticulate package

Python modules are accessible in R via reticulate package. Unfortunately, it is not working for GEKKO, the formulas are not being recognized as such.

I am receiving these kind of error messages when trying to pass equations like in m$Equation(x1 + x2 == 7): Error in x1 + x2 : non-numeric argument to binary operator.

library(reticulate)
gekko <- reticulate::import("gekko")
m <- gekko$GEKKO(remote=TRUE) 
x1 = m$Var(value=1, lb=1, ub=5)
x2 = m$Var(value=5, lb=1, ub=5)
x3 = m$Var(value=5, lb=1, ub=5)
x4 = m$Var(value=1, lb=1, ub=5)
m$Equation(x1 + x2 == 7)
m$Equation(x1 * x2 * x3 * x4 >= 25)
m$Obj(x1 * x4 * (x1 + x2 + x3) + x3)  
m$solve(disp=TRUE)

I would really like to use GEKKO in R, is there some tweak we can do to make that possible?

Reposting the question from a GitHub issue in Gekko repository to see if additional help can be found here. A Python Gekko interface in MATLAB is also possible, if this helps.

% start Matlab from Anaconda prompt
close all; clear;
% Solve linear equations
% Initialize Model
m = py.gekko.GEKKO();
% Initialize Variables
x = m.Var();            % define new variable
y = m.Var();            % default=0
% Define Equations
m.Equation(3*x+2*y==1);
m.Equation(x+2*y==0);  
% Solve
m.solve();
% Extract values from Python lists using curly brackets
disp(['x: ' num2str(x.VALUE{1})]);
disp(['y: ' num2str(y.VALUE{1})]);

Solution

One way would be to run the Python code in R using the py_run_string() command. I have broken up the code using multiple strings to show the steps.

Sys.setenv(RETICULATE_PYTHON = "set the path for python")

library(reticulate)
#Load the package 
str1 = " 
from gekko import GEKKO
m = GEKKO()"

py_run_string(str1)

#Assign values with lower and upper bound along with equations
str2 = "
x1 = m.Var(value=1, lb=1, ub=5)
x2 = m.Var(value=5, lb=1, ub=5)
x3 = m.Var(value=5, lb=1, ub=5)
x4 = m.Var(value=1, lb=1, ub=5)

m.Equation(x1 + x2 == 7)
m.Equation(x1 * x2 * x3 * x4 >= 25)
m.Obj(x1 * x4 * (x1 + x2 + x3) + x3)
m.solve(disp=True)"

py_run_string(str2)

#Print the results
str3="
print('')
print('Results')
print('x1: ' + str(x1.value))
print('x2: ' + str(x2.value))
print('x3: ' + str(x3.value))
print('x4: ' + str(x4.value))
"
py_run_string(str3)

#To access an object
py$x1$VALUE