morphers function

Functions to generate alternate representations of graphs

These functions are meant to be passed into morph() to create a temporary alternate representation of the input graph. They are thus not meant to be called directly. See below for detail of each morpher.

to_linegraph(graph)

to_subgraph(graph, ..., subset_by = NULL)

to_subcomponent(graph, node)

to_split(graph, ..., split_by = NULL)

to_components(graph, type = "weak", min_order = 1)

to_largest_component(graph, type = "weak")

to_complement(graph, loops = FALSE)

to_local_neighborhood(graph, node, order = 1, mode = "all")

to_dominator_tree(graph, root, mode = "out")

to_minimum_spanning_tree(graph, weights = NULL)

to_random_spanning_tree(graph)

to_shortest_path(graph, from, to, mode = "out", weights = NULL)

to_bfs_tree(graph, root, mode = "out", unreachable = FALSE)

to_dfs_tree(graph, root, mode = "out", unreachable = FALSE)

to_simple(graph, remove_multiples = TRUE, remove_loops = TRUE)

to_contracted(graph, ..., simplify = TRUE)

to_unfolded_tree(graph, root, mode = "out")

to_directed(graph)

to_undirected(graph)

to_hierarchical_clusters(graph, method = "walktrap", weights = NULL, ...)

Arguments

• graph: A tbl_graph
• ...: Arguments to pass on to filter(), group_by(), or the cluster algorithm (see igraph::cluster_walktrap(), igraph::cluster_leading_eigen(), and igraph::cluster_edge_betweenness())
• subset_by, split_by: Whether to create subgraphs based on nodes or edges
• node: The center of the neighborhood for to_local_neighborhood() and the node to that should be included in the component for to_subcomponent()
• type: The type of component to split into. Either 'weak' or 'strong'
• min_order: The minimum order (number of vertices) of the component. Components below this will not be created
• loops: Should loops be included. Defaults to FALSE
• order: The radius of the neighborhood
• mode: How should edges be followed? 'out' only follows outbound edges, 'in' only follows inbound edges, and 'all' follows all edges. This parameter is ignored for undirected graphs.
• root: The root of the tree
• weights: Optional edge weights for the calculations
• from, to: The start and end node of the path
• unreachable: Should the search jump to a node in a new component when stuck.
• remove_multiples: Should edges that run between the same nodes be reduced to one
• remove_loops: Should edges that start and end at the same node be removed
• simplify: Should edges in the contracted graph be simplified? Defaults to TRUE
• method: The clustering method to use. Either 'walktrap', 'leading_eigen', or 'edge_betweenness'

Returns

A list of tbl_graphs

Functions

• to_linegraph(): Convert a graph to its line graph. When unmorphing node data will be merged back into the original edge data. Edge data will be ignored.

• to_subgraph(): Convert a graph to a single subgraph. ... is evaluated in the same manner as filter. When unmorphing all data in the subgraph will get merged back.

• to_subcomponent(): Convert a graph to a single component containing the specified node

• to_split(): Convert a graph into a list of separate subgraphs. ...

  is evaluated in the same manner as group_by. When unmorphing all data in the subgraphs will get merged back, but in the case of split_by = 'edges'

  only the first instance of node data will be used (as the same node can be present in multiple subgraphs).

• to_components(): Split a graph into its separate components. When unmorphing all data in the subgraphs will get merged back.

• to_largest_component(): Create a new graph only consisting of it's largest component. If multiple largest components exists, the one with containing the node with the lowest index is chosen.

• to_complement(): Convert a graph into its complement. When unmorphing only node data will get merged back.

• to_local_neighborhood(): Convert a graph into the local neighborhood around a single node. When unmorphing all data will be merged back.

• to_dominator_tree(): Convert a graph into its dominator tree based on a specific root. When unmorphing only node data will get merged back.

• to_minimum_spanning_tree(): Convert a graph into its minimum spanning tree/forest. When unmorphing all data will get merged back.

• to_random_spanning_tree(): Convert a graph into a random spanning tree/forest. When unmorphing all data will get merged back

• to_shortest_path(): Limit a graph to the shortest path between two nodes. When unmorphing all data is merged back.

• to_bfs_tree(): Convert a graph into a breath-first search tree based on a specific root. When unmorphing only node data is merged back.

• to_dfs_tree(): Convert a graph into a depth-first search tree based on a specific root. When unmorphing only node data is merged back.

• to_simple(): Collapse parallel edges and remove loops in a graph. When unmorphing all data will get merged back

• to_contracted(): Combine multiple nodes into one. ...

  is evaluated in the same manner as group_by. When unmorphing all data will get merged back.

• to_unfolded_tree(): Unfold a graph to a tree or forest starting from multiple roots (or one), potentially duplicating nodes and edges.

• to_directed(): Make a graph directed in the direction given by from and to

• to_undirected(): Make a graph undirected

• to_hierarchical_clusters(): Convert a graph into a hierarchical clustering based on a grouping

Examples

# Compute only on a subgraph of every even node
create_notable('meredith') %>%
  morph(to_subgraph, seq_len(graph_order()) %% 2 == 0) %>%
  mutate(neighbour_count = centrality_degree()) %>%
  unmorph()