added a demonstration and some documentation.

Author: DLWoodruff

Diff for: doc/src/agnostic.rst

@@ -21,6 +21,14 @@ option.  Note
 that at the time of this writing, the number of scenarios is obtained
 by counting the mps files in the directory given.
 
+The file ``examples.sizes.mps_demo.txt`` has two commands. The second illustrates
+how to instruction ``MPI-SPPY`` to read mps/json file pairs for each scenario from a
+directory. The first command illustrates how to use ``MPI-SPPY`` to write
+them in the first place (but if ``MPI-SPPY`` can get your scenarios, there
+is probably no reason to write them and then read them again!). This
+functionality is intended to be used by users of other AMLs or other
+scenario-based stochastic programming applications.
+
 
 Tight integration
 ^^^^^^^^^^^^^^^^^

Diff for: examples/sizes/mps_demo.bash

@@ -0,0 +1,23 @@
+#!/bin/bash
+# This is mainly to demonstrate what loose agnostic files look like and
+#   how to use them with agnostic_cylinders.py.
+# To do that, we write the files based on a Pyomo model, then
+# read them in.
+# Note: if you actually have a Pyomo model, you probably don't want to do
+#  it this way since you would have had to have written most of the
+# functions (e.g. scenario_creator) anyway.
+# If you are using some other AML, then you migth want to use the second
+#   command line to read the files you wrote with your AML and
+#   you can use the first command to write files as an example of the format
+#   for the json files.
+
+set -e
+
+SOLVER=cplex
+
+# assumes we are in the sizes directory and don't mind polluting it with 6 files
+python ../../mpisppy/generic_cylinders.py --module-name sizes_expression --num-scens 3 --default-rho 1 --solver-name ${SOLVER} --max-iterations 0 --scenario-lp-mps-files
+
+# By specifying the module to be mps_module we will read files for the problem
+#  from the specified mps-files-directory.
+mpiexec -np 3 python -m mpi4py ../../mpisppy/generic_cylinders.py --module-name ../../mpisppy/utils/mps_module --xhatshuffle --lagrangian --default-rho 1 --solver-name ${SOLVER} --max-iterations 10 --mps-files-directory=.