# `ExVrp.NeighbourhoodParams`
[🔗](https://github.com/sephianl/ex_vrp/blob/v0.4.2/lib/ex_vrp/neighbourhood_params.ex#L1)

Configuration for calculating a granular neighbourhood.

## Attributes

- `weight_wait_time` - Penalty weight given to the minimum wait time aspect
  of the proximity calculation. A large wait time indicates the clients are
  far apart in duration/time.
- `weight_time_warp` - Penalty weight given to the minimum time warp aspect
  of the proximity calculation. A large time warp indicates the clients are
  far apart in duration/time.
- `num_neighbours` - Number of other clients that are in each client's
  granular neighbourhood. This parameter determines the size of the overall
  neighbourhood.
- `symmetric_proximity` - Whether to calculate a symmetric proximity matrix.
  This ensures edge (i, j) is given the same weight as (j, i).
- `symmetric_neighbours` - Whether to symmetrise the neighbourhood structure.
  This ensures that when edge (i, j) is in, then so is (j, i). Note that
  this is *not* the same as `symmetric_proximity`.

## Example

    iex> params = ExVrp.NeighbourhoodParams.new()
    iex> params.weight_wait_time
    0.2
    iex> params.num_neighbours
    60

    iex> params = ExVrp.NeighbourhoodParams.new(num_neighbours: 40)
    iex> params.num_neighbours
    40

# `t`

```elixir
@type t() :: %ExVrp.NeighbourhoodParams{
  num_neighbours: pos_integer(),
  symmetric_neighbours: boolean(),
  symmetric_proximity: boolean(),
  weight_time_warp: float(),
  weight_wait_time: float()
}
```

# `new`

```elixir
@spec new(keyword()) :: t()
```

Creates a new NeighbourhoodParams with the given options.

## Options

- `:weight_wait_time` - Penalty weight for wait time (default: 0.2)
- `:weight_time_warp` - Penalty weight for time warp (default: 1.0)
- `:num_neighbours` - Number of neighbours per client (default: 60)
- `:symmetric_proximity` - Symmetrize proximity matrix (default: true)
- `:symmetric_neighbours` - Symmetrize neighbourhood structure (default: false)

## Raises

- `ArgumentError` when `num_neighbours` is non-positive.

## Examples

    iex> ExVrp.NeighbourhoodParams.new()
    %ExVrp.NeighbourhoodParams{
      weight_wait_time: 0.2,
      weight_time_warp: 1.0,
      num_neighbours: 60,
      symmetric_proximity: true,
      symmetric_neighbours: false
    }

    iex> ExVrp.NeighbourhoodParams.new(num_neighbours: 40, symmetric_neighbours: true)
    %ExVrp.NeighbourhoodParams{
      weight_wait_time: 0.2,
      weight_time_warp: 1.0,
      num_neighbours: 40,
      symmetric_proximity: true,
      symmetric_neighbours: true
    }

---

*Consult [api-reference.md](api-reference.md) for complete listing*