README.md

In readsdr: Translate Models from System Dynamics Software into 'R'

readsdr

Overview

The goal of readsdr is to bridge the design capabilities from specialised System Dynamics software with the powerful numerical tools offered by R libraries. The package accomplishes this goal by parsing .xmile files (Vensim and Stella models) into R objects to construct networks (graph theory), ODE functions for deSolve and Stan.

Installation

You can install the released version of readsdr from CRAN with:

install.packages("readsdr")

And the development version from GitHub with:

# install.packages("devtools")
devtools::install_github("jandraor/readsdr")

Usage

library(readsdr)
filepath <- system.file("models/", "SIR.stmx", package = "readsdr")
mdl      <- read_xmile(filepath) 
summary(mdl)
#>                    Length Class  Mode
#> description        4      -none- list
#> deSolve_components 4      -none- list
#> graph_dfs          2      -none- list

For reading Vensim models, they must be exported as .xmile.

For information on how to use this package, see the vignette or type vignette("Introduction_to_readsdr") in R.

Supported builtins

• Stella
  • Comparison operators (=, <>)
  • Logical operators (AND, OR, NOT)
  • If Else Then
  • Inequality operators (<, >)
  • Pulse 1
  • Step 1
  • Endogenous table functions
  • Smoothing functions: SMTH1, SMTH3, SMTHN
  • Limited support to uni-dimensional arrays. Apply all translation is restricted to numeric values.
  • Math functions: ABS, SQRT
  • Stats functions: NORMAL
• Vensim
  • Comparison operators (=, <>)
  • Logical operators (:AND:, :OR:, :NOT:)
  • IF_THEN_ELSE
  • Inequality operators (<, >)
  • Pulse 1
  • Pulse Train 1
  • Step 1
  • Endogenous table functions
  • Smoothing functions: SMOOTH, SMOOTH3, SMOOTH3I, SMOOTHI
  • Math functions: ABS, SQRT

1 Restricted to Euler integration.

Notes

• uniflow and non-negative stock features from Stella are not supported.

• No built-in is supported for translations to Stan code.

• Modules from Stella are not supported.

Acknowledgments

Thanks to:

• Rogelio Oliva for advocating the need to create an open-source tool for the System Dynamics community and push forward this endeavour.
• Sergey Naumov for his ideas to implement several functions in this package.
• Jim Duggan from whom I borrowed ideas to implement this package.

References

Duggan, J. (2016). System Dynamics Modeling with R. Springer.

readsdr documentation built on Jan. 13, 2021, 11:08 a.m.