The Network module implements the Ulanowicz et al for efficiency, reliability, and sustainability of networks. The module has been written using Elm 0.19 and will have to be tested for 0.18. Minor changes may be required.
The code is in src/Network.elm. A network is described
by nodes and edges. Here are the type definitions:
type Node =
Node String
type Edge =
Edge Node Node Float
type Network =
Network (List Node) (List Edge)
As an example, we create a small network by hand:
u1 = createNode "U1"
u2 = createNode "U2"
u3 = createNode "U3"
u4 = createNode "U4"
e14 = createEdge u1 u4 30
e12 = createEdge u1 u2 90.4
e43 = createEdge u4 u3 22
e23 = createEdge u2 u3 31.4
net = buildNetwork [u1, u2, u3, u4] [e14, e12, e43, e23 ]
These definitions can be found in tests/Example.elm.
Thus we can make various computations as follows.
$ elm repl
> import Examples exposing(..)
> import Network expsoing(..)
> import Flow exposing(..)
> listNodes net
["U1","U2","U3","U4"]
> listEdges net
["U1->U4","U1->U2","U4->U3","U2->U3"]
> listEdgesWithFlow net
["U1->U4: 30","U1->U2: 90.4","U4->U3: 22","U2->U3: 31.4"]
> efficiency net
154.677
> resilience net
149.719 : Float
> alpha net
0.5081441618940449 : Float
> sustainabilityPercentage net
96.99 : Float
To see the structure of net, do this:
> net
Network [Node "U1",Node "U2",Node "U3",Node "U4"] [Edge (Node "U1") (Node "U4") 30,Edge (Node "U1") (Node "U2") 90.4,Edge (Node "U4") (Node "U3") 22,Edge (Node "U2") (Node "U3") 31.4]
: Network
There are facilities for editing a given network in order to experiment with changes in it.
> net2 = insertEdge "U1" "U3" 20 net
> sustainabilityPercentage net2
81.11 : Float
Note that inserting this edge decreased the sustainability.
To delete an edge, use this syntax
deleteEdge name1 name2 network
Here is another experiment:
> net2 = deleteEdge "U1" "U4" net
> sustainabilityPercentage net2
73.02 : Float
> net2 = replaceEdge "U1" "U4" 10 net
> sustainabilityPercentage net2
91.54 : Float
Below is a JSON representation of network we have been working with.
netAsJson = """
{
"nodes": [
{"name": "U1" },
{"name": "U2" },
{"name": "U3" },
{"name": "U4" }
],
"edges": [
{
"from": "U1",
"to": "U4",
"amount": 30
},
{
"from": "U1",
"to": "U2",
"amount": 90.4
},
{
"from": "U4",
"to": "U3",
"amount": 22
},
{
"from": "U2",
"to": "U3",
"amount": 31.4
}
]
}
"""
We can use it as follows:
> import Strings exposing(..) -- netAsJson is defined here
> import Decoder exposing(..) -- For: netWorkFromJson : String -> Network
> net = networkFromJson netAsJson
You an chadk that this is the same net that was defined before.