File Formats#
Instead of building a model using one of the APIs, all model information can be read from a text file. It is also possible to write model information into a text file. Moreover, other information, such as solution values, attributes, or parameters, can be read and written via text files as well. The Gurobi Optimizer works with a variety of text file formats which are discussed in this section.
Note that all of these Gurobi file I/O routines can work with compressed
versions of these files. Specifically, we can read or write files with
the following extensions: .zip, .gz, .bz2, and .7z
(assuming that the associated compression tool, e.g., 7zip for
.7z, is installed on your machine and a corresponding entry is part
of your PATH environment variable).
Model file formats
These text file formats can be used to read or write model information:
File format |
Description |
|---|---|
This is the most widely used format for storing math programming models. It is recommended to use this format (or REW) for optimization. |
|
This format is identical to the MPS format but with anonymized variable and constraint names. |
|
This format is identical to the MPS format but it holds the dual formulation of a pure LP model. |
|
This format is a human readable version of MPS file format. It, however, does not preserve column order when read, and typically does not preserve the exact numerical values of the coefficients. |
|
This format is identical to the LP format but with anonymized variable and constraint names. |
|
This format is identical to the LP format but it holds the dual formulation of a pure LP model. |
|
This format is identical to the LP format but it is used for Irreducible Inconsistent Subsystem (IIS) models. |
|
This format is used to store pseudo-boolean satisfaction and pseudo-boolean optimization models. |
Solution file formats
These text file formats can be used to read or write solution information:
File format |
Description |
|---|---|
This format holds solution information, i.e., solution values for all variables. |
|
This format holds solution information, i.e., solution values for all variables and additional information about the results of the optimization. |
|
This format holds the solution information necessary for a full MIP start. |
|
This format holds simplex basis information. Importing this data into a continuous models allows the simplex algorithm to start from the given simplex basis. |
Solution information can only be written after the model has been optimized and a solution is available. On the other hand, all solution file formats can be used to import solution information to start optimization with a known feasible solution. However, preferably an MST file is used when providing MIP start information for a MIP model. It is also possible to hand over partial solution information, i.e., MST or SOL files that contain only a subset of variables with values.
Other File Formats
File format |
Description |
|---|---|
This format is used to hold MIP hints. Importing this data into a MIP model guides the MIP search towards a guess at a high-quality feasible solution. |
|
This format is used to hold MIP variable branching priorities. Importing this data into a MIP model affects the search strategy. |
|
This format stores a collection of attributes of a model, including (multiple) MIP starts, solution, basis information, partitions, variable hints and branching priorities. |
|
This format holds parameter values. Importing this data into a model changes the values of the referenced parameters. |