hep: go-hep.org/x/hep/fwk/utils/tarjan

## package tarjan

`import "go-hep.org/x/hep/fwk/utils/tarjan"`

package tarjan implements a graph loop detection algorithm called Tarjan's algorithm.

The algorithm takes a input graph and produces a slice where each item is a slice of strongly connected vertices. The input graph is in form of a map where the key is a graph vertex and the value is the edges in for of a slice of vertices.

Algorithm description: http://en.wikipedia.org/wiki/Tarjan’s_strongly_connected_components_algorithm

Based on an implementation by Gustavo Niemeyer (in mgo/txn): http://bazaar.launchpad.net/+branch/mgo/v2/view/head:/txn/tarjan.go

### func Connections¶Uses

`func Connections(graph map[interface{}][]interface{}) [][]interface{}`

Connections creates a slice where each item is a slice of strongly connected vertices.

If a slice item contains only one vertex there are no loops. A loop on the vertex itself is also a connected group.

The example shows the same graph as in the Wikipedia article.

Code:

```graph := make(map[interface{}][]interface{})
graph["1"] = []interface{}{"2"}
graph["2"] = []interface{}{"3"}
graph["3"] = []interface{}{"1"}
graph["4"] = []interface{}{"2", "3", "5"}
graph["5"] = []interface{}{"4", "6"}
graph["6"] = []interface{}{"3", "7"}
graph["7"] = []interface{}{"6"}
graph["8"] = []interface{}{"5", "7", "8"}

o := Connections(graph)
output := sortConnections(o)
fmt.Println(output)```

Output:

```[[1 2 3] [6 7] [4 5] ]
```

Package tarjan is imported by 1 packages. Updated 2019-05-31. Refresh now. Tools for package owners.