ortools-clone/examples/notebook/graph/assignment_linear_assignment.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "864533b2",
   "metadata": {},
   "source": [
    "##### Copyright 2021 Google LLC."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "1a7c5cdc",
   "metadata": {},
   "source": [
    "Licensed under the Apache License, Version 2.0 (the \"License\");\n",
    "you may not use this file except in compliance with the License.\n",
    "You may obtain a copy of the License at\n",
    "\n",
    "    http://www.apache.org/licenses/LICENSE-2.0\n",
    "\n",
    "Unless required by applicable law or agreed to in writing, software\n",
    "distributed under the License is distributed on an \"AS IS\" BASIS,\n",
    "WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n",
    "See the License for the specific language governing permissions and\n",
    "limitations under the License.\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "0b189f3b",
   "metadata": {},
   "source": [
    "# assignment_linear_assignment"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "2c0a4294",
   "metadata": {},
   "source": [
    "<table align=\"left\">\n",
    "<td>\n",
    "<a href=\"https://colab.research.google.com/github/google/or-tools/blob/master/examples/notebook/graph/assignment_linear_assignment.ipynb\"><img src=\"https://raw.githubusercontent.com/google/or-tools/master/tools/colab_32px.png\"/>Run in Google Colab</a>\n",
    "</td>\n",
    "<td>\n",
    "<a href=\"https://github.com/google/or-tools/blob/master/ortools/graph/samples/assignment_linear_assignment.py\"><img src=\"https://raw.githubusercontent.com/google/or-tools/master/tools/github_32px.png\"/>View source on GitHub</a>\n",
    "</td>\n",
    "</table>"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a5afaeea",
   "metadata": {},
   "source": [
    "First, you must install [ortools](https://pypi.org/project/ortools/) package in this colab."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "03440dda",
   "metadata": {},
   "outputs": [],
   "source": [
    "!pip install ortools"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "1c35d019",
   "metadata": {},
   "outputs": [],
   "source": [
    "#!/usr/bin/env python3\n",
    "# Copyright 2010-2021 Google LLC\n",
    "# Licensed under the Apache License, Version 2.0 (the \"License\");\n",
    "# you may not use this file except in compliance with the License.\n",
    "# You may obtain a copy of the License at\n",
    "#\n",
    "#     http://www.apache.org/licenses/LICENSE-2.0\n",
    "#\n",
    "# Unless required by applicable law or agreed to in writing, software\n",
    "# distributed under the License is distributed on an \"AS IS\" BASIS,\n",
    "# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n",
    "# See the License for the specific language governing permissions and\n",
    "# limitations under the License.\n",
    "# [START program]\n",
    "\"\"\"Solve assignment problem using linear assignment solver.\"\"\"\n",
    "# [START import]\n",
    "from ortools.graph import pywrapgraph\n",
    "# [END import]\n",
    "\n",
    "\n",
    "\"\"\"Linear Sum Assignment example.\"\"\"\n",
    "# [START solver]\n",
    "assignment = pywrapgraph.LinearSumAssignment()\n",
    "# [END solver]\n",
    "\n",
    "# [START data]\n",
    "costs = [\n",
    "    [90, 76, 75, 70],\n",
    "    [35, 85, 55, 65],\n",
    "    [125, 95, 90, 105],\n",
    "    [45, 110, 95, 115],\n",
    "]\n",
    "num_workers = len(costs)\n",
    "num_tasks = len(costs[0])\n",
    "# [END data]\n",
    "\n",
    "# [START constraints]\n",
    "for worker in range(num_workers):\n",
    "    for task in range(num_tasks):\n",
    "        if costs[worker][task]:\n",
    "            assignment.AddArcWithCost(worker, task, costs[worker][task])\n",
    "# [END constraints]\n",
    "\n",
    "# [START solve]\n",
    "status = assignment.Solve()\n",
    "# [END solve]\n",
    "\n",
    "# [START print_solution]\n",
    "if status == assignment.OPTIMAL:\n",
    "    print(f'Total cost = {assignment.OptimalCost()}\\n')\n",
    "    for i in range(0, assignment.NumNodes()):\n",
    "        print(f'Worker {i} assigned to task {assignment.RightMate(i)}.' +\n",
    "              f'  Cost = {assignment.AssignmentCost(i)}')\n",
    "elif status == assignment.INFEASIBLE:\n",
    "    print('No assignment is possible.')\n",
    "elif status == assignment.POSSIBLE_OVERFLOW:\n",
    "    print(\n",
    "        'Some input costs are too large and may cause an integer overflow.')\n",
    "# [END print_solution]\n",
    "\n"
   ]
  }
 ],
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