gdxtools

The gdxtools package converts data (parameter or variables) from a GDX file (produced by the GAMS software) into a data.frame. It also provides a function to get information on a GDX file. This package is based on the R interface provided by GAMS software gdxrrw

Installation

As the package cannot be hosted in the R CRAN for now, it has to be installed manually:

if (!requireNamespace("remotes"))
  install.packages("remotes")

remotes::install_github("lolow/gdxtools")

An interesting script can be used to load (and install if necessary) R packages, along with a function to load and install on the fly the gdxtools and its dependencies in a function require_gdxtools (see get_libraries.R)

Usage

library(gdxtools)

# If necessary, tell where is located GAMS.
igdx(dirname(Sys.which('gams'))) 

# define a gdx
> mygdx <- gdx('results.gdx')

# get information on a gdx
> print(mygdx)
<results.gdx, 8 symbols>
> print(mygdx$parameters$name)
[1] param1 param2

# get information on all items in the gdx
> all_items(mygdx)

# create a data.frame from a parameter
> travel_cost <- mygdx["travel_cost"]

# create a data.frame from the lower bound of a variable
> lo_travel_time <- mygdx["travel_time", field="lo"]

# create a data.frame from the marginal value of an equation
> m_time_constraint <- mygdx["time_constraint", field="m"]

# Extract a list of items from many GDX
> myfiles = c("test1.gdx","test2.gdx")
> allparam = batch_extract("myparam",files=myfiles)

# write gdx
> param1 = data.frame(x=c('1','2','4','8'),value=1:4)
> attributes(param1) = c(attributes(param1), gams="definition of parameter 1")
> param2 = data.frame(a=c('london','paris','tahiti'),value=c(50,0.2,1e-2))
> write.gdx("test.gdx",list(param1=param1,param2=param2))

# write a set
> myset1 = data.frame(a=c('london','paris','tahiti'))
> myset2 = data.frame(a=c('london','paris','tahiti'),b=c('tahiti','tahiti','paris'))
> write.gdx("test1.gdx", sets=list(city=myset1,road=myset2))

# write a variable
> var_lower_bound = data.frame(a=c('london','paris','tahiti'),value=1e-2)
> var_level = data.frame(a=c('london','paris','tahiti'),value=0.2)
> var_upper_bound = data.frame(a=c('london','paris','tahiti'),value=50)
> write.gdx("test2.gdx",list(vars_lo=var_lower_bound,vars_l=var_level,vars_up=var_upper_bound))

# debugging the writing of a gdx
> write.gdx("test.gdx", list(param1=param1,param2=param2), removeLST = F, usetempdir = F)

# writing a uncompressed gdx (gdx is compressed by default)
> write.gdx("test.gdx", list(param1=param1,param2=param2), compress = F)

# Write gdx faster using gdxrrw API (but less options are available)
> param1 = data.frame(x=c('1','2','4','8'),value=1:4)
> attributes(param1) = c(attributes(param1), gams="definition of parameter 1")
> param2 = data.frame(a=c('london','paris','tahiti'),value=c(50,0.2,1e-2))
> write2.gdx("test.gdx",list(param1=param1,param2=param2))