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Write a model to MPS, with the index tables needed to read results back

Source: R/highs_solve.R
write_mps.Rd

HiGHS writes MPS quickly precisely because it does not carry symbolic names: the file uses positional ones (c0, r0, ...). The row and column index tables written alongside carry the mapping back to (symbol, index tuple), so a solution vector returned by a remote solver can be interpreted.

Usage

write_mps(
  model,
  file,
  index_dir = dirname(file),
  lp = NULL,
  format = c("parquet", "ipc", "csv"),
  verbose = FALSE,
  presolve = getOption("multimod.presolve", FALSE)
)

Arguments

model

A multimod model with data attached.

file

Path of the .mps file to write.

index_dir

Directory for the index tables; defaults to the directory of file.

lp

Optional pre-built LP from model_to_lp().

format

Storage format for the index tables, passed to the package's .save_dataframe(): "parquet" (default), "ipc" or "csv".

verbose

Logical; report progress.

presolve

Logical; eliminate proportional columns with lp_presolve() before writing. read_mps_solution() restores them. Defaults to getOption("multimod.presolve", FALSE).

Value

Invisibly, a list of the paths written.

Details

The .mps and its index files must travel together - the file alone cannot be mapped back to model symbols.

Examples

if (requireNamespace("highs", quietly = TRUE)) {
  dir <- tempfile("mps-")
  dir.create(dir)
  mps <- file.path(dir, "toy.mps")
  write_mps(example_models$toy, mps, format = "csv")
  list.files(dir)
}
#> WARNING: Column names are not present, or contain duplicates: using names with prefix "c", beginning with suffix 0
#> 
#> WARNING: Row    names are not present, or contain duplicates: using names with prefix "r", beginning with suffix 0
#> 
#> Writing the model to C:\Users\admin\AppData\Local\Temp\RtmpgRRJWR\mps-ba245d30da/toy.mps
#> 
#> [1] "toy.mps"           "toy_col_index.csv" "toy_dim_names.csv"
#> [4] "toy_row_index.csv"