# checkGraph: Checks if the graph contains at least one tree or one... In optrees: Optimal Trees in Weighted Graphs

## Description

The checkGraph function checks if it is possible to find at least one tree (or arborescence, if it is the case) in the graph. It only happens when the graph is connected and it is posible to find a walk from the source to any other node.

## Usage

 1 checkGraph(nodes, arcs, source.node = 1, directed = TRUE)

## Arguments

 nodes vector containing the nodes of the graph, identified by a number that goes from 1 to the order of the graph. arcs matrix with the list of arcs of the graph. Each row represents one arc. The first two columns contain the two endpoints of each arc and the third column contains their weights. source.node number pointing the source node of the graph. directed logical value indicating whether the graph is directed (TRUE) or not (FALSE).

## Value

checkGraph returns the value TRUE if the graph meets the requirements and FALSE otherwise. If the graph is not acceptable this functions also prints the reason.

## Examples

 1 2 3 4 5 6 # Graph nodes <- 1:4 arcs <- matrix(c(1,2,2, 1,3,15, 2,3,1, 2,4,9, 3,4,1), byrow = TRUE, ncol = 3) # Check graph checkGraph(nodes, arcs)

optrees documentation built on May 29, 2017, 9:40 p.m.