# morphers

##### 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.

##### Usage

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

to_subcomponent(graph, node)

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

to_components(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_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)

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 = NA, ...)

##### 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'`

- 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.

- 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'`

##### Value

A list of `tbl_graph`

s

##### 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_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_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

```
# NOT RUN {
# 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()
# }
```

*Documentation reproduced from package tidygraph, version 1.1.2, License: MIT + file LICENSE*