ggraph: Create a ggraph plot

Description

This function is the equivalent of ggplot2::ggplot() in ggplot2. It takes care of setting up the plot object along with creating the layout for the plot based on the graph and the specification passed in. Alternatively a layout can be prepared in advance using create_layout and passed as the data argument. See Details for a description of all available layouts.

Usage

ggraph(graph, layout = "auto", ...)
create_layout(graph, layout, circular, ...)
# S3 method for default
create_layout(graph, layout, ...)
# S3 method for layout_ggraph
create_layout(graph, ...)
# S3 method for tbl_graph
create_layout(graph, layout, circular = FALSE, ...)

Arguments

graph

The object containing the graph. See Details for a list of supported classes. Or a layout_ggraph object as returned from create_layout in which case all subsequent arguments is ignored.

layout

The type of layout to create. Either a valid string, a function, a matrix, or a data.frame (see Details)

...

Arguments passed on to the layout function.

circular

Should the layout be transformed into a radial representation. Only possible for some layouts. Defaults to FALSE

Value

For ggraph() an object of class gg onto which layers, scales, etc. can be added. For create_layout() an object inheriting from layout_ggraph. layout_ggraph itself inherits from data.frame and can be considered as such. The data.frame contains the node positions in the x and y column along with additional columns generated by the specific layout, as well as node parameters inherited from the graph. Additional information is stored as attributes to the data.frame. The original graph object is stored in the graph attribute and the circular attribute contains a logical indicating whether the layout has been transformed to a circular representation.

Details

Following is a short description of the different layout types available in ggraph. Each layout is further described in its own help pages. Any type of regular graph/network data can be represented as a tbl_graph object. Because of this the different layouts that can be applied to tbl_graph objects are quite diverse, but not all layouts makes sense to all types of graphs. It is up to the user to understand their data and choose an appropriate layout. For standard node-edge diagrams igraph defines a long range of different layout functions that are all available through the igraph layout where the specific layout is specified using the algorithm argument. In order to minimize typing all igraph algorithms can also be passed directly into the layout argument.

Any object that has an appropriate as_tbl_graph method can be passed into ggraph() and will automatically be converted underneath.

auto: The default layout. See layout_tbl_graph_auto() for further details
igraph: Use one of the internal igraph layout algorithms. The algorithm is specified using the algorithm argument. All strings accepted by the algorithm argument can also be supplied directly into layout. See layout_tbl_graph_igraph() for further details
dendrogram: Lays out the nodes in a tree-like graph as a dendrogram with leaves set at 0 and parents 1 unit above its tallest child. See layout_tbl_graph_dendrogram() for further details
manual: Lets the user manually specify the location of each node. See layout_tbl_graph_manual() for further details
linear: Arranges the nodes linearly or circularly in order to make an arc diagram. See layout_tbl_graph_linear() for further details
matrix: Arranges nodes on a diagonal thus preparing it for use with geom_edge_point() to make a matrix plot. See layout_tbl_graph_matrix() for further details
treemap: Creates a treemap from the graph, that is, a space-filing subdivision of rectangles showing a weighted hierarchy. See layout_tbl_graph_treemap() for further details
circlepack: Creates a layout showing a hierarchy as circles within circles. Conceptually equal to treemaps. See layout_tbl_graph_circlepack() for further details
partition: Create icicle or sunburst charts, where each layer subdivides the division given by the preceding layer. See layout_tbl_graph_partition() for further details
hive: Positions nodes on axes spreading out from the center based on node attributes. See layout_tbl_graph_hive() for further details

Alternatively a matrix or a data.frame can be provided to the layout argument. In the former case the first column will be used as x coordinates and the second column will by used as y coordinates, further columns are dropped. In the latter case the data.frame is used as the layout table and must thus contain a numeric x and y column.

Lastly a function can be provided to the layout argument. It will be called with the graph object as its first argument and any additional argument passed into ggraph()/create_layout(). The function must return either a data.frame or an object coercible to one and have an x and y column, or an object coercible to a tbl_graph. In the latter case the node data is extracted and used as layout (and must thus contain an x and y column) and the graph will be added as the graph attribute.

Examples

Run this code

# NOT RUN {
require(tidygraph)
gr <- create_notable('bull')
layout <- create_layout(gr, layout = 'igraph', algorithm = 'kk')
# }