R: multilevel layout

layout_multilevel {graphlayouts} | R Documentation

## multilevel layout

### Description

Layout algorithm to visualize multilevel networks

### Usage

    layout_as_multilevel(
      g,
      type = "all",
      FUN1,
      FUN2,
      params1 = NULL,
      params2 = NULL,
      ignore_iso = TRUE,
      project2D = TRUE,
      alpha = 35,
      beta = 45
    )

    layout_igraph_multilevel(
      g,
      type = "all",
      FUN1,
      FUN2,
      params1 = NULL,
      params2 = NULL,
      ignore_iso = TRUE,
      alpha = 35,
      beta = 45,
      circular
    )

### Arguments

`g` | igraph object. Must have a vertex attribute "lvl" which is 1 or 2.
`type` | one of "all", "separate","fix1" or "fix2". see details
`FUN1` | if type="separate", the layout function to be used for level 1
`FUN2` | if type="separate", the layout function to be used for level 2
`params1` | named list of parameters for FUN1
`params2` | named list of parameters for FUN2
`ignore_iso` | treatment of isolates within levels. see details
`project2D` | logical. Defaults to TRUE (project to 2D).
`alpha` | angle for isometric projection between 0 and 90
`beta` | angle for isometric projection between 0 and 90
`circular` | not used

### Details

The algorithm internally computes a 3D layout where each level is in a separate y-plane. The layout is then projected into 2D via an isometric mapping, controlled by the parameters `alpha` and `beta`. It may take some adjusting to `alpha` and `beta` to find a good perspective.

If type="all", the layout is computed at once for the complete network. For type="separate", two user specified layout algorithms (`FUN1` and `FUN2`) are used for the levels. The named lists `param1` and `param2` can be used to set parameters for `FUN1` and `FUN2`. This option helpful for situations where different structural features of the levels should be emphasized.

For type="fix1" and type="fix2" only one of the level layouts is fixed. The other one is calculated by optimizing the inter level ties, such that they are drawn (almost) vertical.

The `ignore_iso` parameter controls the handling of isolates. If TRUE, nodes without inter level edges are ignored during the layout process and added at the end. If FALSE they are left unchanged

The layout_igraph_* function should not be used directly. It is only used as an argument for plotting with 'igraph'.

### Value

matrix of xy coordinates

### Examples

    library(igraph)
    data("multilvl_ex")

    # compute a layout for the whole network
    xy <- layout_as_multilevel(multilvl_ex,type = "all", alpha = 25, beta = 45)

    #compute a layout for each level separately and combine them
    xy <- layout_as_multilevel(multilvl_ex,type = "separate",
                               FUN1 = layout_as_backbone,
                               FUN2 = layout_with_stress,
                               alpha = 25, beta = 45)

[Package graphlayouts version 0.8.0 Index]