SupplyNetPy

https://github.com/supplychainsimulation/supplynetpy
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SupplyNetPy is a Python library for modeling, simulating, and optimizing supply chains and inventory...
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### Example: Simple Supply Chain

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/REVIEW.md

Canonical example demonstrating a basic supply chain setup. The profit, total cost, and transportation cost remain unchanged after the Link registration fix.

```python
from supplychainpy import demand, environment, inventory, manufacturer, link


env = environment.Environment()

# Nodes
demand_node = demand.Demand(env=env, name='Demand')
inventory_node = inventory.Inventory(env=env, name='Inventory', unit_cost=1.0, unit_capacity=1000)

# Links
link_demand_inventory = link.Link(env=env, source=demand_node, sink=inventory_node, cost=1.0, lead_time=lambda: 1)

# Run simulation
results = env.run(until=5)

# Print results
print(f"profit: {results.profit:.1f}")
print(f"total_cost: {results.total_cost:.1f}")
print(f"transportation_cost: {results.transportation_cost:.1f}")
```

--------------------------------

### Run Quick-Start Example

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/CLAUDE.md

Execute the canonical quick-start example to perform a sanity check on core semantics. The expected output is profit = -4435.0.

```bash
python examples/py/intro_simple.py
```

--------------------------------

### Serve and Build Documentation Locally

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/CLAUDE.md

Install documentation dependencies and then serve or build the documentation locally using mkdocs.

```bash
pip install -r docs/requirements.txt
```

```bash
mkdocs serve
```

```bash
mkdocs build
```

--------------------------------

### Newsvendor Simulation Setup

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/docs/example-newvendor.md

This Python script sets up and runs a simulation for the newsvendor problem. It configures an infinite supplier, a newsvendor with perishable inventory and periodic replenishment, and normally distributed demand. Ensure the script is placed in the correct directory relative to the 'examples' folder.

```python
from supplychainpy.demand_models.demand_models import normal_quantity
from supplychainpy.inventory_models.inventory_models import Inventory
from supplychainpy.order_policies.order_policies import OrderPolicy
from supplychainpy.simulations.simulations import Simulation
from supplychainpy.supplier_models.supplier_models import InfiniteSupplier
from supplychainpy.node import Node

# Simulation parameters
order_quantity = 110
num_days = 365

# Create nodes
supplier = InfiniteSupplier()
newsvendor = Node(
    inventory_model=Inventory(level=order_quantity, perishable_shelf_life=1),
    order_policy=OrderPolicy(policy_type='periodic', reorder_frequency=1),
    demand_model=normal_quantity(mean=100, stdev=20),
    consume_available=True
)

# Create simulation
sim = Simulation(num_days=num_days)
sim.add_supplier(supplier=supplier, node=newsvendor)
sim.run_simulation()

# Analyze results
sim.plot_profit_curve(order_quantity=order_quantity)

```

--------------------------------

### Install SupplyNetPy

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/README.md

Install the library using pip. Ensure you have Python and pip installed.

```sh
pip install supplynetpy
```

--------------------------------

### Install SupplyNetPy and Dependencies

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/validation/README.md

Install the necessary libraries for SupplyNetPy, including simpy, numpy, and matplotlib.

```bash
pip install supplynetpy simpy numpy matplotlib
```

--------------------------------

### Setup Simulation Environment

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/examples/notebooks/case_study_pharma.ipynb

Initializes the simulation environment, including supplier, distributor, link, and demand processes. Configures node disruption and recovery times using geometric distributions.

```python
def setup_simulation(env, s, S, ini_level, st, disrupt_time, recovery_time):
    """Setup environment, supplier, distributor, link, and demand process."""
    supplier = scm.Supplier(env, "S1", "Supplier 1", "infinite_supplier", 
                            node_disrupt_time=disrupt_time.geometric, 
                            node_recovery_time=recovery_time.geometric)

    distributor = scm.InventoryNode(env, "D1", "Distributor 1", "distributor",
                                    capacity=float('inf'), initial_level=ini_level,
                                    inventory_holding_cost=h, inventory_type="perishable",
                                    manufacture_date=manufacturer_date_cal, shelf_life=e,
                                    replenishment_policy=scm.SSReplenishment,
                                    policy_param={'s': s, 'S': S},
                                    product_buy_price=0, product_sell_price=price)

    link = scm.Link(env, "l1", supplier, distributor, cost=o, lead_time=lambda: l)

    demand = scm.Demand(env, "d1", "demand 1", order_arrival_model=lambda: 1,
                        order_quantity_model=st.poisson_demand, demand_node=distributor)

    return supplier, distributor, demand, link
```

--------------------------------

### Setup Simulation Environment

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/docs/case_study_pharma.md

Defines the simulation environment, including suppliers, distributors, links, and demand processes. Used for initializing a new simulation run.

```python
def setup_simulation(env, s, S, ini_level, st, disrupt_time, recovery_time):
    """Setup environment, supplier, distributor, link, and demand process."""
    supplier = scm.Supplier(env=env, ID="S1", name="Supplier 1", node_type="infinite_supplier",
                            node_disrupt_time=disrupt_time.geometric,
                            node_recovery_time=recovery_time.geometric)

    distributor = scm.InventoryNode(env=env, ID="D1", name="Distributor 1", node_type="distributor",
                                    capacity=float('inf'), initial_level=ini_level,
                                    inventory_holding_cost=h, inventory_type="perishable",
                                    manufacture_date=manufacturer_date_cal, shelf_life=e,
                                    replenishment_policy=scm.SSReplenishment,
                                    policy_param={'s': s, 'S': S},
                                    product_buy_price=0, product_sell_price=price)

    link = scm.Link(env=env, ID="l1", source=supplier, sink=distributor,
                    cost=o, lead_time=lambda: l)

    demand = scm.Demand(env=env, ID="d1", name="demand 1", order_arrival_model=lambda: 1,
                        order_quantity_model=st.poisson_demand, demand_node=distributor)

    return supplier, distributor, demand, link
```

--------------------------------

### EOQ Simulation Setup and Execution

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/examples/notebooks/EOQ_est.ipynb

Sets up the simulation environment, defines supply chain components (supplier, inventory node, link, demand), and runs the simulation for a specified length. It iterates through different lot sizes to collect cost and unmet demand data.

```python
import simpy
import numpy as np
import matplotlib.pyplot as plt
import SupplyNetPy.Components as scm

"""
 Demand for the Deskpro computer at Best Buy is 1,000 units per month. Best Buy incurs a fixed order placement, 
 transportation, and receiving cost of $4,000 each time an order is placed. Each computer costs Best Buy $500 
 and the retailer has a holding cost of 20 percent. Evaluate the number of computers that the store manager 
 should order in each replenishment lot. 
 
 Analysis:
 In this case, the store manager has the following inputs:
 - Annual demand, D = 1,000 * 12 = 12,000 units (approx 34 units per day)
 - Order cost per lot, S = 4,000 
 - Unit cost per computer, C = 500
 - Holding cost per year as a fraction of unit cost, h = 0.2 (500*0.2 = 100 per year => 100/365 = 0.273 per day)

 Assumptions:
 - Demand is constant and deterministic
 - Lead time is zero

Optimum Economic Order Quantity (EOQ) is determined to minimize the total cost.
Total cost = Annual material cost + Annual ordering cost + Annual holding cost
This is same as -> Total cost = total transportation cost + inventory cost (we'll ignore material cost since it is constant)
"""

D = 12000 # annual demand
d = 34 # daily demand
order_cost = 4000 # order cost
unit_cost = 500 # unit cost
holding_cost = 0.273 # holding cost per day
lead_time = 0 # lead time

simlen = 3650 # simulation length in days

total_cost_arr = []
unsat_arr = []
print(f"lot size 	 Inv holding cost 	 Order cost 	 Average cost(per day) 	 Unmet demand")
for lot_size in range(800,1600,10):

    order_interval = 365*lot_size/D
    
    env = simpy.Environment()
    
    hp_supplier = scm.Supplier(env=env, ID="S1", name="HPComputers", node_type="infinite_supplier")

    bestbuy = scm.InventoryNode(env=env, ID="D1", name="Best Buy", node_type="distributor",
                                    capacity=lot_size, initial_level=lot_size, inventory_holding_cost=holding_cost,
                                    replenishment_policy=scm.PeriodicReplenishment, product_buy_price=450,
                                    policy_param={'T':order_interval,'Q':lot_size}, product_sell_price=unit_cost)

    link1 = scm.Link(env=env,ID="l1", source=hp_supplier, sink=bestbuy, cost=order_cost, lead_time=lambda: lead_time)

    demand1 = scm.Demand(env=env,ID="d1", name="demand_d1", order_arrival_model=lambda: 1, 
                        order_quantity_model=lambda: d, demand_node=bestbuy, consume_available=True)
    scm.global_logger.disable_logging() # disable logging for all components
    env.run(until=simlen)

    bb_invlevels = np.array(bestbuy.inventory.instantaneous_levels)
    hp_sup_transportation_cost = bestbuy.stats.transportation_cost

    total_cost = bestbuy.stats.inventory_carry_cost + bestbuy.stats.transportation_cost
    total_cost_arr.append([lot_size, total_cost/simlen])
    
    unsat_demand = demand1.stats.demand_placed[1]-demand1.stats.fulfillment_received[1]
    unsat_arr.append([lot_size,unsat_demand])
    print(f"{lot_size} 		 {bestbuy.stats.inventory_carry_cost:.2f}		{bestbuy.stats.transportation_cost}		{total_cost/simlen:.2f}		{unsat_demand:.2f}")

total_cost_arr = np.array(total_cost_arr)
unsat_arr = np.array(unsat_arr)
EOQ = np.argmin(total_cost_arr[:,1])

plt.figure()
plt.plot(total_cost_arr[:,0], total_cost_arr[:,1],marker='.',linestyle='-')
plt.plot(total_cost_arr[EOQ,0], total_cost_arr[EOQ,1],marker='o',color='red',label=f'EOQ = {total_cost_arr[EOQ,0]:.2f} with cost = {total_cost_arr[EOQ,1]:.2f}')
plt.xlabel("lot size")
plt.ylabel("Average cost per day")
plt.title("Average cost vs lot size")
plt.legend()
plt.grid()

plt.show()
```

--------------------------------

### Example: Supply Chain with Factory

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/REVIEW.md

Example featuring a manufacturer node. The core metrics (profit, total cost, transportation cost) are verified to be consistent after the Link registration refactoring.

```python
from supplychainpy import demand, environment, inventory, manufacturer, link


env = environment.Environment()

# Nodes
demand_node = demand.Demand(env=env, name='Demand')
inventory_node = inventory.Inventory(env=env, name='Inventory', unit_cost=1.0, unit_capacity=1000)
manufacturer_node = manufacturer.Manufacturer(env=env, name='Manufacturer', unit_cost=2.0, unit_capacity=500)

# Links
link_demand_inventory = link.Link(env=env, source=demand_node, sink=inventory_node, cost=1.0, lead_time=lambda: 1)
link_inventory_manufacturer = link.Link(env=env, source=inventory_node, sink=manufacturer_node, cost=1.0, lead_time=lambda: 1)

# Run simulation
results = env.run(until=5)

# Print results
print(f"profit: {results.profit:.1f}")
print(f"total_cost: {results.total_cost:.1f}")
print(f"transportation_cost: {results.transportation_cost:.1f}")
```

--------------------------------

### Example: Link Construction with Plain Node

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/REVIEW.md

Demonstrates successful Link construction when the sink is a plain Node instance. Previously, this would raise an AttributeError because plain Nodes did not have a suppliers attribute.

```python
from supplychainpy import environment, node, link

env = environment.Environment()

# Nodes
source_node = node.Node(env=env, name='Source')
plain_node = node.Node(env=env, name='PlainNode')

# Link construction that now succeeds
link_obj = link.Link(env=env, source=source_node, sink=plain_node, cost=1, lead_time=lambda: 1)

# Verification: plain_node.suppliers should now be a list containing link_obj
print(f"plain_node.suppliers == [link_obj]: {plain_node.suppliers == [link_obj]}")
```

--------------------------------

### Install SupplyNetPy in Editable Mode

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/CLAUDE.md

Use this command to install the library in editable mode for development purposes.

```bash
pip install -e .
```

--------------------------------

### Create and Simulate Supply Chain Network

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/README.md

Example demonstrating how to create a supply chain network with suppliers, distributors, and demand nodes, and then simulate its behavior over a specified time period. Requires importing the SupplyNetPy Components module.

```python
import SupplyNetPy.Components as scm

supplier1 = {'ID': 'S1', 'name': 'Supplier1', 'node_type': 'infinite_supplier'}

distributor1 = {'ID': 'D1', 'name': 'Distributor1', 'node_type': 'distributor', 
                'capacity': 150, 'initial_level': 50, 'inventory_holding_cost': 0.2, 
                'replenishment_policy': scm.SSReplenishment, 'policy_param': {'s':100,'S':150},
                'product_buy_price': 100,'product_sell_price': 105}

link1 = {'ID': 'L1', 'source': 'S1', 'sink': 'D1', 'cost': 5, 'lead_time': lambda: 2}

demand1 = {'ID': 'd1', 'name': 'Demand1', 'order_arrival_model': lambda: 1,
            'order_quantity_model': lambda: 10, 'demand_node': 'D1'}

# create a supply chain network
supplychainnet = scm.create_sc_net(nodes=[supplier1, distributor1], links=[link1], demands=[demand1])

# simulate for 20 days
supplychainnet = scm.simulate_sc_net(supplychainnet, sim_time=20, logging=True)
```

--------------------------------

### Define Supply Chain Network Components and Links

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/examples/notebooks/simple_supplier_n_factory.ipynb

Initializes simulation environment, defines raw materials, supplier, product, manufacturer, distributor, and links between them. This setup includes defining capacities, costs, and replenishment policies.

```python
simtime = 365
env = simpy.Environment()
raw_mat = scm.RawMaterial(ID="RM1", name="raw materials mouse", extraction_quantity=650,
                          extraction_time=3, mining_cost=0.01, cost=0.1)
#supplier = scm.Supplier(env=env, ID='S1', name='Supplier', node_type="infinite_supplier", raw_material=raw_mat)
supplier = scm.Supplier(env=env, ID='S1', name='Supplier', node_type="supplier", raw_material=raw_mat, capacity=5000, 
                        initial_level=5000, inventory_holding_cost=0.1)
mouse = scm.Product(ID="MW11", name="Toad M11", manufacturing_cost=10, manufacturing_time=1, sell_price=300, buy_price=150,
                             raw_materials=[(raw_mat,1)], batch_size=2500)
factory = scm.Manufacturer(env=env, ID='F1', name='Factory Cansaulim', capacity=2500, initial_level=800, shelf_life=10,
                           inventory_holding_cost=0.1, replenishment_policy=scm.SSReplenishment, policy_param={'s':1500, 'S':2500}, 
                           product=mouse, product_sell_price=300, inventory_type="perishable")
distributor = scm.InventoryNode(env=env, ID='D1', name='Mumbai Warehouse', node_type="warehouse", shelf_life=10,
                                capacity=1000, initial_level=1000, inventory_holding_cost=0.22,
                                replenishment_policy = scm.RQReplenishment, policy_param={'R':500, 'Q':500}, 
                                product_buy_price=300, product_sell_price=320, inventory_type="perishable")
link1 = scm.Link(env=env, ID='L1', source=supplier, sink=factory, cost=10, lead_time=lambda: 1)
link2 = scm.Link(env=env, ID='L2', source=factory, sink=distributor, cost=10, lead_time=lambda: 1)
demand1 = scm.Demand(env=env, ID='demand_D1', name='Demand Pune', order_arrival_model=lambda: 2, order_quantity_model=lambda:50, 
                     delivery_cost=lambda:10, lead_time=lambda:0.9, demand_node=distributor)
demand2 = scm.Demand(env=env, ID='demand_D2', name='Demand Kalyan', order_arrival_model=lambda: 1, order_quantity_model=lambda:35, 
                     delivery_cost=lambda:10, lead_time=lambda:0.9, demand_node=distributor)
```

--------------------------------

### Configure Inventory Node for Power-Outage Disruption

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/docs/api-reference/api-intro.md

This example shows how to configure an InventoryNode to simulate a power-outage style disruption, where a random fraction of the current shelf stock is destroyed. The `disruption_impact` is set to 'destroy_fraction', and `disruption_loss_fraction` is a lambda function generating a random uniform value between 0.1 and 0.4.

```python
warehouse = scm.InventoryNode(
    ..., disruption_impact="destroy_fraction",
    disruption_loss_fraction=lambda: random.uniform(0.1, 0.4),
)
```

--------------------------------

### Initialize Simulation Environment

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/docs/safety_inv_est.md

Sets up the simulation environment using simpy and numpy for demand generation. It defines daily demand parameters and the total simulation length.

```python
import simpy
import numpy as np
import matplotlib.pyplot as plt
import SupplyNetPy.Components as scm

daily_demand_mean = 2500/7
daily_demand_std = 500/(7**0.5)
simlen = 3650 # simulation length in days

def normal_quantity():
    global daily_demand_mean, daily_demand_std
    sample = -1
    while sample < 0:
        sample = np.random.normal(daily_demand_mean, daily_demand_std, 1)[0]
    return sample

env = simpy.Environment()
```

--------------------------------

### Example: Invalid Link Registration Sink Mismatch

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/REVIEW.md

Demonstrates the ValueError raised when a Link is registered with a sink node that is not its designated sink.

```python
from supplychainpy import environment, node, link

env = environment.Environment()

source_node1 = node.Node(env=env, name='Source1')
source_node2 = node.Node(env=env, name='Source2')
sink_node = node.Node(env=env, name='Sink')

link_obj = link.Link(env=env, source=source_node1, sink=sink_node, cost=1, lead_time=lambda: 1)

# Attempt to add link_obj to a different node's suppliers, expecting ValueError
try:
    source_node2.add_supplier_link(link_obj)
except ValueError as e:
    print(f"Caught expected error: {e}")
```

--------------------------------

### Create Network and Run Simulation

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/docs/example.md

Initializes the supply chain network with defined nodes and links, then executes the simulation for a specified duration.

```python
network = SupplyChainNetwork()
network.add_node(supplier_node)
network.add_node(factory_node)
network.add_node(distributor_node)
network.add_links(links)

network.simulate(time=5)
```

--------------------------------

### Example: Invalid Link Registration Type

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/REVIEW.md

Illustrates the TypeError raised when attempting to register an object that is not a Link instance with the add_supplier_link method.

```python
from supplychainpy import environment, node, link

env = environment.Environment()

source_node = node.Node(env=env, name='Source')
sink_node = node.Node(env=env, name='Sink')

# Attempt to add a non-Link object, expecting TypeError
try:
    sink_node.add_supplier_link('not a link')
except TypeError as e:
    print(f"Caught expected error: {e}")
```

--------------------------------

### Import Libraries for Supply Chain Simulation

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/examples/notebooks/simple_supplier_n_factory.ipynb

Imports necessary libraries for simulation, data handling, and plotting. Ensure these are installed before running the simulation.

```python
import numpy as np
import random
import simpy
import matplotlib.pyplot as plt
import SupplyNetPy.Components as scm
```

--------------------------------

### Node.place_order() Method

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/REVIEW.md

Wraps the process of selecting a supplier and initiating an order. Policies now use this method instead of directly interacting with the selection policy and order processing logic.

```python
def place_order(self, quantity) -> None:
    supplier = self.selection_policy.select(quantity)
    self.env.process(self.process_order(supplier, quantity))
```

--------------------------------

### Create Factory Node and Product

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/docs/example.md

Configures a factory node that produces products. It includes settings for product creation and factory inventory management with replenishment thresholds.

```python
product_node = {
    "id": "product",
    "type": "product",
    "inventory": {
        "product": {
            "capacity": 1000,
            "min_quantity": 200,
            "max_quantity": 1000
        }
    }
}

factory_node = {
    "id": "factory",
    "type": "factory",
    "product": "product",
    "production": {
        "product": {
            "quantity": 100,
            "time": 1,
            "cost": 1
        }
    },
    "replenishment": {
        "product": {
            "s": 300,
            "S": 1000
        }
    }
}
```

--------------------------------

### Generate Supply Chain Network and Measure Time

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/examples/notebooks/performance_ana.ipynb

Generates a supply chain network with a specified number of nodes and measures the time taken for its creation. This function helps in understanding the overhead of network setup.

```python
replenishment_policies = [scm.SSReplenishment, scm.RQReplenishment, scm.PeriodicReplenishment]
selection_policies = [scm.SelectAvailable, scm.SelectCheapest, scm.SelectFirst, scm.SelectFastest]
selection_mode = ["fixed","dynamic"]

def generate_supply_chain(n: int, simtime: int, logging: bool = False) -> float:
    """
    Generate a supply chain network with n nodes and measure execution time.

    Node Ratios (Generalized for Balanced Networks):
    - Suppliers to Manufacturers: 3–10 suppliers per manufacturer
    - Manufacturers to Warehouses/Distributors: 1–3 per manufacturer
    - Warehouses/Distributors to Retailers: 1–10 per warehouse/distributor
    """
    env = simpy.Environment()
    supplynet = {"env": env, "nodes": {}, "links": {}, "demands": {}}

    if n < 4:
        print("Cannot create a network with fewer than 4 nodes!")
        return

    # Determine node counts
    num_suppliers = max(1, n // 5)
    num_manufacturers = max(1, n // 10)
    num_distributors = max(1, n // 7)
    num_retailers = n - num_suppliers - num_manufacturers - num_distributors

    #print(f"num_suppliers={num_suppliers}, num_manufacturers={num_manufacturers}, num_distributors={num_distributors}, num_retailers={num_retailers}")

    # Create product and raw material
    rawmat = scm.RawMaterial(ID="rm1", name="raw_material", extraction_time=1,
                             extraction_quantity=100, mining_cost=0.1, cost=1)
    product = scm.Product(ID="p1", name="product", manufacturing_cost=1, manufacturing_time=1,
                          raw_materials=[(rawmat, 1)], sell_price=10, batch_size=100)

    # Helper function for generating random attributes
    def rand_attrs(init_range, hold_range, s_range, buy_range=None, sell_range=None):
        attrs = {
            "initial_level": random.randint(*init_range),
            "inventory_holding_cost": random.uniform(*hold_range),
            "s": random.randint(*s_range)
        }
        if buy_range: attrs["buy"] = random.randint(*buy_range)
        if sell_range: attrs["sell"] = random.randint(*sell_range)
        return attrs

    # Create suppliers
    for i in range(1, num_suppliers + 1):
        ID = f"S{i}"
        supplynet["nodes"][ID] = scm.Supplier(env, ID=ID, name=f"Supplier {i}",
                                              node_type="infinite_supplier", raw_material=rawmat)

    max_dem = int(DemandDist().mean*(DemandDist().mean+DemandDist().var))
    min_dem = int(DemandDist().mean*(DemandDist().mean-DemandDist().var))

    dmax_dem = (num_retailers//num_distributors)*max_dem
    dmin_dem = (num_retailers//num_distributors)*min_dem
    
    mmax_dem = (num_distributors//num_manufacturers)*dmax_dem
    mmin_dem = (num_distributors//num_manufacturers)*dmin_dem

    #print(f"max_dem={max_dem}, min_dem={min_dem}, dmax_dem={dmax_dem}, dmin_dem={dmin_dem}, mmax_dem={mmax_dem}, mmin_dem={mmin_dem}")

    # Create manufacturers
    for i in range(1, num_manufacturers + 1):
        ID = f"M{i}"
        attrs = rand_attrs((mmin_dem, mmax_dem), (0.2, 0.5), (mmin_dem, mmax_dem), sell_range=(product.sell_price, product.sell_price+1))
        supplynet["nodes"][ID] = scm.Manufacturer(env, ID=ID, name=f"Manufacturer {i}",
                                                   capacity=mmax_dem,
                                                   initial_level=attrs["initial_level"],

```

--------------------------------

### Build Network with Classmethod Constructor

Source: https://context7.com/supplychainsimulation/supplynetpy/llms.txt

Constructs a supply network using the Network.build classmethod, defining nodes, links, and demands. The network is then simulated.

```python
import SupplyNetPy.Components as scm

net = scm.Network.build(
    nodes=[
        {'ID': 'S1', 'name': 'Supplier', 'node_type': 'infinite_supplier'},
        {'ID': 'D1', 'name': 'Distributor', 'node_type': 'distributor',
         'capacity': 200, 'initial_level': 80, 'inventory_holding_cost': 0.1,
         'replenishment_policy': scm.RQReplenishment,
         'policy_param': {'R': 50, 'Q': 100},
         'product_buy_price': 50, 'product_sell_price': 60},
    ],
    links=[{'ID': 'L1', 'source': 'S1', 'sink': 'D1', 'cost': 3, 'lead_time': lambda: 1}],
    demands=[{'ID': 'd1', 'name': 'Demand', 'order_arrival_model': lambda: 2,
              'order_quantity_model': lambda: 15, 'demand_node': 'D1'}]
)
net.simulate(sim_time=100, logging=False)

# Typed accessors
print(net.node_count)           # 2
print(net.link_count)           # 1
print(net.node('D1').stats.inventory_level)

# Post-run KPIs via .results
r = net.results
print(r['profit'], r['shortage'], r['inventory_carry_cost'])
```

--------------------------------

### Run Simulation with Replenishment and Demand

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/examples/notebooks/different_replenish_policies_anylogistix.ipynb

This snippet sets up and runs a discrete-event simulation. It defines replenishment and demand processes and executes the simulation until a specified time. Ensure 'env', 'inventory', 'replenish', and 'demand' are properly initialized before running.

```python
print(f"{env.now}:A: Shipment received. Inventory replenished to {inventory.level}")
        else:
            yield inv_drop

replenish_event = env.process(replenish(env, inventory))
demand_event = env.process(demand(env, inventory))

env.run(until=10)
print(f"Inventory lvl: {inventory.level}")
```

--------------------------------

### Fix Inventory Expiry Event Handling in SupplyNetPy

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/REVIEW.md

This fix ensures that the SimPy 'get' event is yielded when removing expired items, maintaining consistency between container levels and on-hand counts. It resolves issues with inaccurate holding cost calculations.

```python
if qty > 0:
    get_event, _ = self.get(qty)
    yield get_event
```

--------------------------------

### Initialize Supplier Node with Direct API

Source: https://context7.com/supplychainsimulation/supplynetpy/llms.txt

Initializes an infinite supplier node using the direct API with a simpy environment. Supports disruption modeling parameters like failure probability and recovery time.

```python
import simpy
import SupplyNetPy.Components as scm

env = simpy.Environment()
scm.set_seed(42)  # reproducible disruptions

# Infinite supplier (unlimited stock)
sup = scm.Supplier(env=env, ID='S1', name='Supplier', node_type='infinite_supplier')
```

--------------------------------

### Import SupplyNetPy and SimPy

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/validation/README.md

Import the SupplyNetPy library as 'scm' and the simpy library for simulation.

```python
import SupplyNetPy as scm
import simpy
```

--------------------------------

### Updating pyproject.toml Dependencies and Python Version

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/REVIEW.md

Updates pyproject.toml to require Python >=3.9, drops support for Python 3.8, adds support for Python 3.12, and explicitly lists networkx and matplotlib as dependencies. This ensures the library installs correctly and avoids reliance on incidentally present packages.

```toml
[project]
requires-python = ">=3.9"
classifiers = [
    "Programming Language :: Python :: 3.9",
    "Programming Language :: Python :: 3.10",
    "Programming Language :: Python :: 3.11",
    "Programming Language :: Python :: 3.12",
]
dependencies = [
    "networkx",
    "matplotlib",
]
```

--------------------------------

### Initialize and Run Simulation for Expected Costs

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/examples/notebooks/case_study_pharma.ipynb

Initializes and runs a simulation to calculate expected costs per day for a given range of reorder points. The results are stored in a NumPy array.

```python
exp_cost_per_day = np.array([[1300, 7.077822120396403, 15.375530317761504, 0.48621696037098827], [1400, 8.072049149524776, 8.944250976240237, 0.2828420504910372],
                              [1500, 8.177269862608554, 8.759889885683231, 0.27701204091031023],[1600, 7.855598168510199, 8.654408519286562, 0.273676427225108],
                              [1700, 7.877377475166987, 8.572385582297002, 0.27108263421247314],[1800, 8.310096514871837, 8.127115493237646, 0.2570019576587373],
                              [1900, 8.391168946106205, 7.832646240299199, 0.24769002225700004]])
```

```python
exp_cost_per_day5 = np.array([[100, 25.30862172992034, 15.375530317761504, 0.48621696037098827], [200, 18.16593400246117, 16.986714360773185, 0.5371670734273444],
                              [300, 17.650956809395268, 16.973452926426557, 0.5367477100515831], [400, 15.589053570872546, 16.870657435971335, 0.533497031221257],
                              [500, 15.498871274512553, 15.421650748015102, 0.48767541643367135], [600, 13.898840987447143, 15.368269057506792, 0.48598733916010683],
                              [700, 13.78142778173988, 15.215801669376146, 0.4811658970062092], [800, 13.20616981550624, 15.448069084740641, 0.48851083759413116],
                              [900, 11.804738360182338, 13.481785962414833, 0.4263315056811608]])
```

--------------------------------

### Print and Get Node-wise Performance Metrics in SupplyNetPy

Source: https://context7.com/supplychainsimulation/supplynetpy/llms.txt

Use `print_node_wise_performance` to display KPIs as a text table or `get_node_wise_performance` to retrieve them as structured data for analysis. The code requires importing SupplyNetPy components and simulating a network first. Individual node statistics can also be accessed directly from the node object.

```python
import SupplyNetPy.Components as scm

# Build and simulate
net = scm.create_sc_net(
    nodes=[
        {'ID': 'S1', 'name': 'Supplier',    'node_type': 'infinite_supplier'},
        {'ID': 'D1', 'name': 'Distributor', 'node_type': 'distributor',
         'capacity': 200, 'initial_level': 100, 'inventory_holding_cost': 0.2,
         'replenishment_policy': scm.SSReplenishment, 'policy_param': {'s': 60, 'S': 200},
         'product_buy_price': 10, 'product_sell_price': 14},
    ],
    links=[{'ID': 'L1', 'source': 'S1', 'sink': 'D1', 'cost': 2, 'lead_time': lambda: 1}],
    demands=[{'ID': 'd1', 'name': 'Demand', 'order_arrival_model': lambda: 1,
              'order_quantity_model': lambda: 8, 'demand_node': 'D1'}],
)
scm.simulate_sc_net(net, sim_time=50, logging=False)

node_list = list(net['nodes'].values())
# Print table to stdout
scm.print_node_wise_performance(node_list)

# Get structured data for further analysis
rows = scm.get_node_wise_performance(node_list)
# Each row: {'Performance Metric': 'profit', 'Distributor': 1234.5, ...}
import pandas as pd
df = pd.DataFrame.from_records(rows)
print(df.to_string(index=False))

# Or access a single node's stats directly
d1 = net['nodes']['D1']
stats = d1.stats.get_statistics()
# stats keys: name, demand_placed, fulfillment_received, demand_received,
#             demand_fulfilled, shortage, backorder, inventory_level,
#             inventory_waste, inventory_carry_cost, inventory_spend_cost,
#             transportation_cost, destroyed_qty, destroyed_value,
#             node_cost, revenue, profit
print(f"D1 profit: {stats['profit']}, shortage: {stats['shortage']}")
```

--------------------------------

### Build Network with Dictionary Wrapper

Source: https://context7.com/supplychainsimulation/supplynetpy/llms.txt

Creates a supply network by wrapping an existing dictionary structure using scm.create_sc_net and then initializing a Network object. The legacy dictionary remains in sync.

```python
import SupplyNetPy.Components as scm

# Style B: wrap existing dict
sc = scm.create_sc_net(nodes=[...], links=[...], demands=[...])
net2 = scm.Network(sc)
net2.simulate(200)
# Legacy dict still in sync:
print(net2.as_dict()['profit'])
```

--------------------------------

### Simulate and Calculate EOQ with SupplyNetPy

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/docs/EOQ_est.md

This script simulates inventory management to find the Economic Order Quantity (EOQ). It iterates through different lot sizes, calculates total daily costs (ordering + holding), and identifies the lot size that minimizes these costs. The simulation uses `simpy` for discrete-event simulation and `SupplyNetPy` components for inventory and supplier nodes. It also visualizes the cost per lot size and highlights the calculated EOQ.

```python
import simpy
import numpy as np
import matplotlib.pyplot as plt
import SupplyNetPy.Components as scm

"""
 Demand for the Deskpro computer at Best Buy is 1,000 units per month. Best Buy incurs a fixed order placement, 
 transportation, and receiving cost of $4,000 each time an order is placed. Each computer costs Best Buy $500 
 and the retailer has a holding cost of 20 percent. Evaluate the number of computers that the store manager 
 should order in each replenishment lot. 

 Analysis:
 In this case, the store manager has the following inputs:
 - Annual demand, D = 1,000 * 12 = 12,000 units (approx 34 units per day)
 - Order cost per lot, S = 4,000 
 - Unit cost per computer, C = 500
 - Holding cost per year as a fraction of unit cost, h = 0.2 (500*0.2 = 100 per year => 100/365 = 0.273 per day)

 Assumptions:
 - Demand is constant and deterministic
 - Lead time is zero

Optimum Economic Order Quantity (EOQ) is determined to minimize the total cost.
Total cost = Annual material cost + Annual ordering cost + Annual holding cost
This is same as -> Total cost = total transportation cost + inventory cost (we'll ignore material cost since it is constant)
"""

D = 12000 # annual demand
d = 34 # daily demand
order_cost = 4000 # order cost
unit_cost = 500 # unit cost
holding_cost = 0.273 # holding cost per day
lead_time = 0 # lead time

simlen = 3650 # simulation length in days

total_cost_arr = []
unsat_arr = []
print(f"lot size \t Inv holding cost \t Order cost \t Average cost(per day) \t Unmet demand")
for lot_size in range(800,1600,10):

    order_interval = 365*lot_size/D
    
    env = simpy.Environment()
    
    hp_supplier = scm.Supplier(env=env, ID="S1", name="HPComputers", node_type="infinite_supplier")

    bestbuy = scm.InventoryNode(env=env, ID="D1", name="Best Buy", node_type="distributor",
                                    capacity=lot_size, initial_level=lot_size, inventory_holding_cost=holding_cost,
                                    replenishment_policy=scm.PeriodicReplenishment, product_buy_price=450,
                                    policy_param={'T':order_interval,'Q':lot_size}, product_sell_price=unit_cost)

    link1 = scm.Link(env=env,ID="l1", source=hp_supplier, sink=bestbuy, cost=order_cost, lead_time=lambda: lead_time)

    demand1 = scm.Demand(env=env,ID="d1", name="demand_d1", order_arrival_model=lambda: 1, 
                        order_quantity_model=lambda: d, demand_node=bestbuy, consume_available=True)
    scm.global_logger.disable_logging() # disable logging for all components
    env.run(until=simlen)

    bb_invlevels = np.array(bestbuy.inventory.instantaneous_levels)
    hp_sup_transportation_cost = bestbuy.stats.transportation_cost

    total_cost = bestbuy.stats.inventory_carry_cost + bestbuy.stats.transportation_cost
    total_cost_arr.append([lot_size, total_cost/simlen])
    
    unsat_demand = demand1.stats.demand_placed[1]-demand1.stats.fulfillment_received[1]
    unsat_arr.append([lot_size,unsat_demand])
    print(f"{lot_size} \t\t {bestbuy.stats.inventory_carry_cost:.2f}\t\t{bestbuy.stats.transportation_cost}\t\t{total_cost/simlen:.2f}\t\t{unsat_demand:.2f}")

total_cost_arr = np.array(total_cost_arr)
unsat_arr = np.array(unsat_arr)
EOQ = np.argmin(total_cost_arr[:,1])

plt.figure()
plt.plot(total_cost_arr[:,0], total_cost_arr[:,1],marker='.',linestyle='-')
plt.plot(total_cost_arr[EOQ,0], total_cost_arr[EOQ,1],marker='o',color='red',label=f'EOQ = {total_cost_arr[EOQ,0]:.2f} with cost = {total_cost_arr[EOQ,1]:.2f}')
plt.xlabel("lot size")
plt.ylabel("Average cost per day")
plt.title("Average cost vs lot size")
plt.legend()
plt.grid()

plt.show()

```

--------------------------------

### Switching to nx.multipartite_layout for Visualization

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/REVIEW.md

Implements nx.multipartite_layout keyed by a new _TIER_INDEX for improved visualization. This arranges nodes left-to-right (suppliers to demand) and ensures arrows render correctly with nx.DiGraph.

```python
nx.multipartite_layout
```

--------------------------------

### Create and Simulate Supply Chain Network

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/docs/ten_min.md

Use `create_sc_net` to instantiate and assemble supply chain nodes, adding metadata. Then, use `simulate_sc_net` to run the simulation over a specified period and log performance metrics.

```python
from supplychainpy import create_sc_net, simulate_sc_net

# Create and simulate the supply chain network
supplychainnet = create_sc_net(name='my_supply_chain', json_file='scipy_example.json')
log = simulate_sc_net(supplychainnet, 100)

```

--------------------------------

### Configure Retailer Nodes and Demand in SupplyNet

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/examples/notebooks/performance_ana.ipynb

Sets up retailer nodes with capacities and various replenishment policies. Demand is modeled using exponential arrival and uniform quantity distributions. Links are created from distributors to retailers.

```python
# Create retailers and demand
    for i in range(1, num_retailers + 1):
        ID = f"R{i}"
        attrs = rand_attrs((min_dem, max_dem), (1, 1.5), (min_dem, max_dem), buy_range=(product.sell_price, product.sell_price+2), sell_range=(product.sell_price+2, product.sell_price+3))
        supplynet["nodes"][ID] = scm.InventoryNode(env, ID=ID, name=f"Retailer {i}", node_type="retailer",
                                                   capacity=max_dem,
                                                   initial_level=attrs["initial_level"],
                                                   inventory_holding_cost=attrs["inventory_holding_cost"],
                                                   replenishment_policy=random.choice(replenishment_policies),
                                                   policy_param={'s': attrs["s"], 'S': max_dem, 'R':attrs["s"], 'Q': min_dem, 'T': 1},
                                                   product_buy_price=attrs["buy"], product_sell_price=attrs["sell"],
                                                   supplier_selection_policy=scm.SelectAvailable,
                                                   supplier_selection_mode="dynamic")
        # Demand
        demand_id = f"demand_{ID}"
        supplynet["demands"][demand_id] = scm.Demand(env, ID=demand_id, name=f"Demand {i}",
                                                     order_arrival_model=DemandDist().exponential, # around 10 orders per day
                                                     order_quantity_model=DemandDist().uniform, # around 10 units per order
                                                     demand_node=supplynet["nodes"], ID])
        # Links from distributors to retailer
        for j in range(1, num_distributors + 1):
            link_id = f"Ld{j}r{i}"
            supplynet["links"][link_id] = scm.Link(env, ID=link_id,
                                                   source=supplynet["nodes"]["D{j}"],
                                                   sink=supplynet["nodes"], ID],
                                                   cost=random.randint(1, 3),

```

--------------------------------

### Build Distribution Package

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/CLAUDE.md

Use hatchling to build the distribution package for the project.

```bash
python -m build
```

--------------------------------

### Replenishment Before Demand Simulation

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/examples/notebooks/different_replenish_policies_anylogistix.ipynb

This simulation demonstrates a scenario where replenishment orders are placed before demand arrives. Observe how inventory is replenished before demand is processed, ensuring demand fulfillment.

```text
Process A: Replenishment is created.
Process B: Demand is created.
0:B: Demand for 1 
0:B: Fulfilled, Inventory: 0.0
0:A: Ordering replenishment for 1 units
2.0:B: Demand for 1 
2.0:B: not fulfilled at, Inventory: 0.0
2.0:A: Shipment received. Inventory replenished to 1.0
4.0:B: Demand for 1 
4.0:B: Fulfilled, Inventory: 0.0
4.0:A: Ordering replenishment for 1 units
6.0:B: Demand for 1 
6.0:B: not fulfilled at, Inventory: 0.0
6.0:A: Shipment received. Inventory replenished to 1.0
8.0:B: Demand for 1 
8.0:B: Fulfilled, Inventory: 0.0
8.0:A: Ordering replenishment for 1 units
Inventory lvl: 0.0
```

--------------------------------

### Run Single Simulation Instance

Source: https://github.com/supplychainsimulation/supplynetpy/blob/main/docs/case_study_pharma.md

Executes a single simulation run with specified parameters and returns the normalized cost. Includes initial warm-up period.

```python
def single_sim_run(S, s, ini_level, logging=True):
    """Run a single simulation instance and return expected cost."""
    env = simpy.Environment()
    st = Distributions(mu=1, lam=dt)
    disrupt_time = Distributions(p=yt_p)
    recovery_time = Distributions(p=yt_r)

    supplier, distributor, demand, link = setup_simulation(env, s, S, ini_level, st, disrupt_time, recovery_time)
    
    pharma_chain = scm.create_sc_net(env=env, nodes=[supplier, distributor], links=[link], demands=[demand])
    pharma_chain = scm.simulate_sc_net(pharma_chain,sim_time=30,logging=logging)
    supplier.stats.reset()
    distributor.stats.reset()
    demand.stats.reset()
    pharma_chain = scm.simulate_sc_net(pharma_chain,sim_time=T,logging=logging)

    shortage = distributor.stats.shortage[1]
    waste = distributor.stats.inventory_waste
    holding = distributor.stats.inventory_carry_cost
    transport = distributor.stats.transportation_cost

    total_cost = (shortage * b + waste * z + holding + transport)
    norm_cost = total_cost / ((T - 30) * (b + z + h + o)) * price

    if logging:
        print("Shortage cost:", shortage * b)
        print("Waste cost:", waste * z)
        print("Holding cost:", holding)
        print("Transportation cost:", transport)
    
    return norm_cost
```
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