is_connected {autoharp} | R Documentation |

## Checks if a graph is connected.

### Description

A tree is a graph that is connected but does not have any cycles. This function checks if a provided adjacency list is connected.

### Usage

```
is_connected(adj_list, root = 1)
```

### Arguments

`adj_list` |
The adjacency list of the tree. |

`root` |
The root node to start checking from. This defaults to the first node in the adjacency list. |

### Details

This function is used as one of the validity checks within the definition of the TreeHarp class. It is a low-level function, not really meant for the general user of the package. Hence it is not exported.

The nodes are traversed in a BFS order. The function could actually be combined with is_cyclic_r, but it is kept separate for modularity reasons.

An alternative was to convert the list to an adjacency matrix and check for a row and column of zeros.

### Value

The function returns a TRUE if the graph is connected and FALSE otherwise.

*autoharp*version 0.0.10 Index]