net1.json

{
  "Problem": {
    "Name": "general_transshipment",
    "Reference": "https://ampl.com/BOOK/EXAMPLES/EXAMPLES2/net1.mod",
    "Author": "Jeremy A. Bloom (jeremyblmca@gmail.com)",
    "Notices": "Copyright © 2019 Jeremy A. Bloom"
  },
  "Input_Data_Model": {
    "cities": {
      "*city":              "String",
      "netSupply":          "Double"
    },
    "links": {
      "*origin":            "String",
      "*destination":       "String",
      "cost":               "Double",
      "capacity":           "Double"
    }
  },
  "Output_Data_Model": {
    "ship": {
      "*origin(city)":      "String",
      "*destination(city)": "String",
      "packages":           "Double"
    }
  },
  "Data": {
    "cities": [
      {"city": "PITT", "netSupply": 450.0},
      {"city": "NE", "netSupply": 0.0},
      {"city": "SE", "netSupply": 0.0},
      {"city": "BOS", "netSupply": -90.0},
      {"city": "EWR", "netSupply": -120.0},
      {"city": "BWI", "netSupply": -120.0},
      {"city": "ATL", "netSupply": -70.0},
      {"city": "MCO", "netSupply": -50.0}
    ],
    "links": [
      {"origin": "PITT", "destination": "NE", "cost": 2.5, "capacity": 250.0},
      {"origin": "PITT", "destination": "SE", "cost": 3.5, "capacity": 250.0},
      {"origin": "NE", "destination": "BOS", "cost": 1.7, "capacity": 100.0},
      {"origin": "NE", "destination": "EWR", "cost": 0.7, "capacity": 100.0},
      {"origin": "NE", "destination": "BWI", "cost": 1.3, "capacity": 100.0},
      {"origin": "SE", "destination": "EWR", "cost": 1.3, "capacity": 100.0},
      {"origin": "SE", "destination": "BWI", "cost": 0.8, "capacity": 100.0},
      {"origin": "SE", "destination": "ATL", "cost": 0.2, "capacity": 100.0},
      {"origin": "SE", "destination": "MCO", "cost": 2.1, "capacity": 100.0}
    ]
  },
  "Variables": [
    {
      "Name": "ship",
      "Type": "Continuous",
      "Index": "links",
      "Bounds": {"Lower": 0.0, "Upper": "links.capacity"}
    }
  ],
  "Constraints": [
    {
      "Name": "balance",
      "Type": "Linear",
      "Index": "cities",
      "Sense": "==",
      "RHS": "cities.netSupply"
    }
  ],
  "Decision_Expressions": [
    {
      "Name": "totalCost",
      "Type": "Linear",
      "Index": "Self",
      "Sense": "minimize"
    }
  ],
  "Coefficients": [
    {
      "Name": "balance_shipFrom",
      "Constraints": "balance",
      "Variables": {"Name":"ship", "Index": "links.origin(city)"},
      "Entries": 1.0
    },
    {
      "Name": "balance_shipTo",
      "Constraints": "balance",
      "Variables": {"Name":"ship", "Index": "links.destination(city)"},
      "Entries": -1.0
    },
    {
      "Name": "total_ship",
      "Decision_Expressions": "totalCost",
      "Variables": "ship",
      "Entries": "links.cost"
    }
  ]
}