Command Line Tools

Starting wth version 1.4.0, Platypus offers several command-line tools. To see all available options, run:

platypus --help

Solve

Solve executes the given algorithm on a problem, saving the final approximation set as JSON:

platypus solve --algorithm NSGAII --problem DTLZ2 --nfe 10000 --output NSGAII_DTLZ2.set

Additional arguments can be provided, such as setting the population_size as demonstrated below. Note that only arguments with primitive types are supported.

platypus solve --algorithm NSGAII --problem DTLZ2 --nfe 10000 population_size=250

INFO:Platypus:Setting population_size=250 on NSGAII
INFO:Platypus:NSGAII starting
INFO:Platypus:NSGAII finished; Total NFE: 10000, Elapsed Time: 0:00:06.216727

Performance Indicators

Now that we have the output from a run, we can compute any performance indicator. Here, we calculate the hypervolume using a reference set for normalization:

platypus hypervolume --reference_set ./examples/DTLZ2.2D.pf NSGAII_DTLZ2.set

which outputs:

0.23519328623761482

Filtering

The results can be filtered to remove any dominated, infeasible, or duplicate solutions:

platypus filter --output NSGAII_DTLZ2_unique.set --feasible --unique NSGAII_DTLZ2.set
platypus filter --output NSGAII_DTLZ2_epsilons.set --epsilons 0.01,0.01 NSGAII_DTLZ2.set

Normalization

Most performance indicators are normalized, meaning the objectives are scaled by some minimum and maximum bounds. This is useful to make results comparable across different studies, assuming the same reference set or bounds are supplied. Here, we can generate the normalized solutions:

platypus normalize --output NSGAII_DTLZ2_normalized.set --reference_set ./examples/DTLZ2.2D.pf NSGAII_DTLZ2.set
platypus normalize --output NSGAII_DTLZ2_normalized.set --minimum 0.0,0.0 --maximum 1.0,1.0 NSGAII_DTLZ2.set

Plotting

For 2 and 3 objectives, we can also generate a plot, either interactive or saving as an image:

platypus plot NSGAII_DTLZ2.set
platypus plot --output NSGAII_DTLZ2.png NSGAII_DTLZ2.set

Combining or Chaining Commands

On systems that support piping the output from one command into another (i.e., cmd1 | cmd2), we can also use this to combine these CLI tools. Simply exclude the input and output filenames, as demonstrated below:

platypus solve --algorithm NSGAII --problem DTLZ2 --nfe 10000 | \
    platypus filter --epsilons 0.01,0.01 | \
    platypus plot