reorganize all examples in the examples directory

examples/python/integer_programming.py

@@ -0,0 +1,122 @@
+# Copyright 2010-2011 Google
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Integer programming examples that show how to use the APIs."""
+
+__author__ = """lperron@google.com (Laurent Perron)
+                edanna@google.com (Emilie Danna)"""
+
+from google.apputils import app
+
+from linear_solver import pywraplp
+
+
+def RunIntegerExampleNaturalLanguageAPI(optimization_problem_type):
+  """Example of simple integer program with natural language API."""
+  solver = pywraplp.Solver('RunIntegerExampleNaturalLanguageAPI',
+                           optimization_problem_type)
+  infinity = solver.Infinity()
+  # x1 and x2 are integer non-negative variables.
+  x1 = solver.IntVar(0.0, infinity, 'x1')
+  x2 = solver.IntVar(0.0, infinity, 'x2')
+
+  solver.Minimize(x1 + 2 * x2)
+  solver.Add(3 * x1 + 2 * x2 >= 17)
+
+  SolveAndPrint(solver, [x1, x2])
+
+
+def RunIntegerExampleCppStyleAPI(optimization_problem_type):
+  """Example of simple integer program with the C++ style API."""
+  solver = pywraplp.Solver('RunIntegerExampleCppStyleAPI',
+                           optimization_problem_type)
+  infinity = solver.Infinity()
+  # x1 and x2 are integer non-negative variables.
+  x1 = solver.IntVar(0.0, infinity, 'x1')
+  x2 = solver.IntVar(0.0, infinity, 'x2')
+
+  # Minimize x1 + 2 * x2.
+  solver.SetObjectiveCoefficient(x1, 1)
+  solver.SetObjectiveCoefficient(x2, 2)
+
+  # 2 * x2 + 3 * x1 >= 17.
+  ct = solver.Constraint(17, infinity)
+  ct.SetCoefficient(x1, 3)
+  ct.SetCoefficient(x2, 2)
+
+  SolveAndPrint(solver, [x1, x2])
+
+
+def SolveAndPrint(solver, variable_list):
+  """Solve the problem and print the solution."""
+  print 'Number of variables = %d' % solver.NumVariables()
+  print 'Number of constraints = %d' % solver.NumConstraints()
+
+  result_status = solver.Solve()
+
+  # The problem has an optimal solution.
+  assert result_status == pywraplp.Solver.OPTIMAL
+
+  print 'Problem solved in %f milliseconds' % solver.WallTime()
+
+  # The objective value of the solution.
+  print 'Optimal objective value = %f' % solver.ObjectiveValue()
+
+  # The value of each variable in the solution.
+  for variable in variable_list:
+    print '%s = %f' % (variable.name(), variable.SolutionValue())
+
+  print 'Advanced usage:'
+  print 'Problem solved in %d branch-and-bound nodes' % solver.Nodes()
+
+
+def Announce(solver, api_type):
+  print ('---- Integer programming example with ' + solver + ' (' +
+         api_type + ') -----')
+
+
+def RunAllIntegerExampleNaturalLanguageAPI():
+  if hasattr(pywraplp.Solver, 'GLPK_MIXED_INTEGER_PROGRAMMING'):
+    Announce('GLPK', 'natural language API')
+    RunIntegerExampleNaturalLanguageAPI(
+        pywraplp.Solver.GLPK_MIXED_INTEGER_PROGRAMMING)
+  if hasattr(pywraplp.Solver, 'CBC_MIXED_INTEGER_PROGRAMMING'):
+    Announce('CBC', 'natural language API')
+    RunIntegerExampleNaturalLanguageAPI(
+        pywraplp.Solver.CBC_MIXED_INTEGER_PROGRAMMING)
+  if hasattr(pywraplp.Solver, 'SCIP_MIXED_INTEGER_PROGRAMMING'):
+    Announce('SCIP', 'natural language API')
+    RunIntegerExampleNaturalLanguageAPI(
+        pywraplp.Solver.SCIP_MIXED_INTEGER_PROGRAMMING)
+
+
+def RunAllIntegerExampleCppStyleAPI():
+  if hasattr(pywraplp.Solver, 'GLPK_MIXED_INTEGER_PROGRAMMING'):
+    Announce('GLPK', 'C++ style API')
+    RunIntegerExampleCppStyleAPI(pywraplp.Solver.GLPK_MIXED_INTEGER_PROGRAMMING)
+  if hasattr(pywraplp.Solver, 'CBC_MIXED_INTEGER_PROGRAMMING'):
+    Announce('CBC', 'C++ style API')
+    RunIntegerExampleCppStyleAPI(pywraplp.Solver.CBC_MIXED_INTEGER_PROGRAMMING)
+  if hasattr(pywraplp.Solver, 'SCIP_MIXED_INTEGER_PROGRAMMING'):
+    Announce('SCIP', 'C++ style API')
+    RunIntegerExampleCppStyleAPI(
+        pywraplp.Solver.SCIP_MIXED_INTEGER_PROGRAMMING)
+
+
+def main(unused_argv):
+  RunAllIntegerExampleNaturalLanguageAPI()
+  RunAllIntegerExampleCppStyleAPI()
+
+
+if __name__ == '__main__':
+  app.run()