Add file with usage of Mixed Integer Programming with Pulp

lab_mip.py

@@ -0,0 +1,76 @@
+#    Copyright 2016 Mirantis, Inc.
+#
+#    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 then
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+
+from pulp import *
+import sys
+
+x = []
+y = []
+
+thismodule = sys.modules[__name__]
+
+for i in range(6):
+    name = 'x{0}'.format(i + 1)
+    var = LpVariable(name, 0, None)
+    setattr(thismodule, name, var)
+    x.append(var)
+
+for i in range(6):
+    name = 'y{0}'.format(i + 1)
+    var = LpVariable(name, 0, 1, 'Binary')
+    setattr(thismodule, name, var)
+    y.append(var)
+
+
+# defines the problem
+prob = LpProblem("problem", LpMaximize)
+
+# defines the objective function to maximize
+prob += x1 + x2 + x3 + x4 + x5 + x6, 'Sum of spaces'
+
+
+# defines the constraints
+prob += x1 + x2 <= 100, 'First disk'
+prob += x3 + x4 <= 100, 'Second disk'
+prob += x5 + x6 <= 100, 'Third disk'
+
+prob += y1 + y3 + y5 == 2, 'Replication factor'
+
+prob += x1 + x3 + x5 >= 20, 'First min size'
+prob += x2 + x4 + x6 >= 101, 'Second min size'
+
+prob += x1 - x5 == 0, 'Sizes equality for raid'
+
+# Convert from Float to Integer
+for i, x_ in enumerate(x):
+    y_ = y[i]
+
+    prob += y_ - x_ <= 0
+    prob += x_ - 100 * y_ <= 0
+
+# solve the problem
+status = prob.solve(GLPK(msg=1))
+
+def print_vector(vector, prefix, n=2):
+
+    for i, v in enumerate(vector):
+        sys.stdout.write('{0}_{1} = {2}'.format(prefix, i + 1, value(v)))
+        if (i + 1) % n:
+            sys.stdout.write('\t')
+        else:
+            sys.stdout.write('\n')
+
+print_vector(x, 'x')
+print_vector(y, 'y')