igraph (version 0.2.1)

layout: Generate coordinates for plotting graphs

Description

Some simple and not so simple functions determining the placement of the vertices for drawing a graph.

Usage

layout.random(graph, params, dim=2)
layout.circle(graph, params)
layout.sphere(graph, params)
layout.fruchterman.reingold(graph, ..., dim=2,
      verbose=igraph.par("verbose"), params)
layout.kamada.kawai(graph, ..., dim=2,
      verbose=igraph.par("verbose"), params)
layout.spring(graph, ..., params)
layout.reingold.tilford(graph, ..., params)
layout.fruchterman.reingold.grid(graph, ...,
      verbose=igraph.par("verbose"), params)
layout.lgl(graph, ..., params)

Arguments

graph

The graph to place.

params

The list of function dependent parameters.

dim

Numeric constant, either 2 or 3. Some functions are able to generate 2d and 3d layouts as well, supply this argument to change the default behavior.

...

Function dependent parameters, this is an alternative notation to the params argument.

verbose

Logial constant, whether to show a progress bar while calculating the layout.

Value

• All these functions return a numeric matrix with at least two columns and the same number of lines as the number of vertices.

code

area

itemize

• maxiter

item

• sigma
• initemp
• coolexp
• kkconst
• equil
• k
• repeqdis
• kfr
• repulse
• maxdelta
• area
• coolexp
• repulserad
• cellsize
• maxdelta
• area
• coolexp
• repulserad
• cellsize
• root

sQuote

• quasi-kilograms
• quasi-meters
• quasi-Newtons per quasi-meter
• quasi-meters
• quasi-Newton quasi-kilograms

url

http://bioinformatics.icmb.utexas.edu/lgl

Details

These functions calculate the coordinates of the vertices for a graph usually based on some optimality criterion.

layout.random simply places the vertices randomly on a square. It has no parameters.

layout.circle places the vertices on a unit circle equidistantly. It has no paramaters.

layout.sphere places the vertices (approximately) uniformly on the surface of a sphere, this is thus a 3d layout. It is not clear however what uniformly on a sphere means. layout.fruchterman.reingold uses a force-based algorithm proposed by Fruchterman and Reingold, see references. Parameters and their default values:

• niter

{Numeric, the number of iterations to perform (500).} coolexp{Numeric, the cooling exponent for the simulated annealing (3).} maxdelta{Maximum change (vcount(graph)).} area{Area parameter (vcount(graph)^2).} repulserad{Cancellation radius (area*vcount(graph)).}

References

Fruchterman, T.M.J. and Reingold, E.M. (1991). Graph Drawing by Force-directed Placement. Software - Practice and Experience, 21(11):1129-1164.

Kamada, T. and Kawai, S. (1989). An Algorithm for Drawing General Undirected Graphs. Information Processing Letters, 31(1):7-15.

Reingold, E and Tilford, J (1981). Tidier drawing of trees. IEEE Trans. on Softw. Eng., SE-7(2):223--228.

See Also

plot.igraph, tkplot

Examples

g <- graph.ring(10)
layout.random(g)
layout.kamada.kawai(g)