Types of networks

One feature of EcologicalNetwork which makes the rest of the package works is the type system to represent networks. This is not the most enthralling reading, but this pacge will walk you through the different options, and discuss how and when to use them.

Network representation

All networks types have a field A to store the adjacency matrix, and fields S, or T and B, for species in unipartite and bipartite networks respectively. A is always a two-dimensional array (see below for more information), where interactions go from the rows, to the columns. Network types are mutable. Operations that will modify the network end with a !, as is the julian convention.

Fields S, T, and B are one-dimensional arrays of AllowedSpeciesTypes -- they currently can be String or Symbol, and represent the species/nodes names. Future allowed types will be added in later releases.

You should never have to manipulate the network by calling its fields directly. The species function will give you access to the species, and the network slicing operations (see later sections) will let you access subset of the network / individual interactions / set of neighbours.

Network types are currently not iterable, but this may be built into a next release.

Partiteness

In unipartite networks, the adjancency matrix A is square, and has as many rows/columns as there are elements in S. This is always checked and enforced upon construction of the object, so you cannot have a mismatch.

In bipartite networks, the matrix A is not necessarily square, and has dimensions equal to the lengths of T (rows) and B (columns). This too is checked upon construction.

All elements in S must be unique (no duplicate node names). In addition, all names in the union of T and B must be unique too (so that when a bipartite network is cast to a unipartite one, the constraint on unique names in S is respected).

Type of information

At all points, you can have a look at the types of the interactions and the species objects -- the next entries in this documentation give additional information about the types allowed.

```@docs eltype

## Union types

All networks are grouped upon the `AbstractEcologicalNetwork` type:

```@docs
AbstractEcologicalNetwork

All allowed types for nodes are part of the AllowedSpeciesTypes type:

```@docs AllowedSpeciesTypes

### By partiteness

```@docs
AbstractBipartiteNetwork
AbstractUnipartiteNetwork

By interaction type

```@docs BinaryNetwork QuantitativeNetwork ProbabilisticNetwork DeterministicNetwork

## List of available types

These are the types that you *actually* declare and use. They are presented last
because it is easier to understand what they are when you get a sense for the
different union types.

```@docs
UnipartiteNetwork
BipartiteNetwork
UnipartiteQuantitativeNetwork
BipartiteQuantitativeNetwork
UnipartiteProbabilisticNetwork
BipartiteProbabilisticNetwork