Central vertices of a graph

The center of a graph is the set of its vertices with minimal eccentricity.

graph_center(graph, ..., weights = NULL, mode = c("all", "out", "in", "total"))

Arguments

graph: The input graph, it can be directed or undirected.
...: These dots are for future extensions and must be empty.
weights: Possibly a numeric vector giving edge weights. If this is NULL and the graph has a weight edge attribute, then the attribute is used. If this is NA then no weights are used (even if the graph has a weight attribute). In a weighted graph, the length of a path is the sum of the weights of its constituent edges.
mode: Character constant, gives whether the shortest paths to or from the given vertices should be calculated for directed graphs. If out then the shortest paths from the vertex, if in then to it will be considered. If all, the default, then the graph is treated as undirected, i.e. edge directions are not taken into account. This argument is ignored for undirected graphs.

Value

The vertex IDs of the central vertices.

Examples

tree <- make_tree(100, 7)
graph_center(tree)
#> + 2/100 vertices, from d1c8716:
#> [1] 1 2
graph_center(tree, mode = "in")
#> + 1/100 vertex, from d1c8716:
#> [1] 1
graph_center(tree, mode = "out")
#> + 85/100 vertices, from d1c8716:
#>  [1]  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34
#> [20]  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53
#> [39]  54  55  56  57  58  59  60  61  62  63  64  65  66  67  68  69  70  71  72
#> [58]  73  74  75  76  77  78  79  80  81  82  83  84  85  86  87  88  89  90  91
#> [77]  92  93  94  95  96  97  98  99 100

# Without and with weights
ring <- make_ring(10)
graph_center(ring)
#> + 10/10 vertices, from 6e713ad:
#>  [1]  1  2  3  4  5  6  7  8  9 10
# Add weights
E(ring)$weight <- seq_len(ecount(ring))
graph_center(ring)
#> + 1/10 vertex, from 6e713ad:
#> [1] 7

Arguments

Value

See also

Related documentation in the C library

Examples