These algorithms assign each node to a layer, which becomes one axis,
and a position within that layer, which becomes the other.
They are recommended for use with graphr() or {ggraph},
and suit two-mode networks and directed acyclic networks.
The four layouts are one engine drawn four ways, and differ only in which axis carries the layers and in how each layer is spread out:
| Layers stacked flat | Layers standing up | |
alignment = "straight" | "layered" | "lineage" |
alignment = "rungs" | "railway" | "ladder" |
That is, the "layered" layout places the first node set along the bottom and the second node set along the top, sequenced and spaced as necessary to minimise tie overlap. The "lineage" layout is the same layout with the axes exchanged, so that successive layers run left to right rather than bottom to top. The "railway" and "ladder" layouts are "layered" and "lineage" with every layer given the same spacing, so that the nodes line up across the layers like the rails and rungs the names describe.
Usage
layout_layered(
.data,
center = NULL,
ranks = c("tight", "generation", "compact"),
alignment = c("straight", "rungs"),
circular = FALSE,
times = 1000
)
layout_tbl_graph_layered(
.data,
center = NULL,
ranks = c("tight", "generation", "compact"),
alignment = c("straight", "rungs"),
circular = FALSE,
times = 1000
)
layout_lineage(
.data,
ranks = c("tight", "generation", "compact"),
alignment = c("straight", "rungs"),
circular = FALSE,
times = 1000,
rank = NULL
)
layout_tbl_graph_lineage(
.data,
ranks = c("tight", "generation", "compact"),
alignment = c("straight", "rungs"),
circular = FALSE,
times = 1000,
rank = NULL
)
layout_railway(
.data,
ranks = c("tight", "generation", "compact"),
circular = FALSE,
times = 1000
)
layout_tbl_graph_railway(
.data,
ranks = c("tight", "generation", "compact"),
circular = FALSE,
times = 1000
)
layout_ladder(
.data,
ranks = c("tight", "generation", "compact"),
circular = FALSE,
times = 1000
)
layout_tbl_graph_ladder(
.data,
ranks = c("tight", "generation", "compact"),
circular = FALSE,
times = 1000
)Arguments
- .data
Some
{manynet}compatible network data.- center
Further split a "layered" layout by declaring the "center" argument as the "events", "actors", or by declaring a node name. Defaults to NULL.
- ranks
How the layers are assigned: "tight" (the default) chooses the layers that make the total tie length as short as possible, while still pointing every tie down at least one layer; "generation" ranks each node by its distance from a root, so that a layer is a generation, at the cost of some longer ties; "compact" asks
igraph::layout_with_sugiyama()for the layers. The first two need an acyclic network, and fall back to "compact" where the network is not. Ignored for a two-mode network, whose layers are its modes.A node attribute can be given here instead, either as the name of a numeric node attribute or as a numeric vector as long as the network has nodes. Then the layers are those values, and nodes are placed along that axis in proportion to them rather than at even steps, so that a network of dated nodes is drawn as a timeline. The values run in the same direction as the layers the engine works out: down the page in a "layered" or "railway" layout, and left to right in a "lineage" or "ladder" layout, so that the smallest value comes first.
- alignment
How each layer is spread out: "straight" (the default) draws the ties as close to straight as the ordering allows, which groups the nodes that belong together; "rungs" gives every layer the same integer spacing, so that the nodes line up across the layers.
- circular
Should the layout be transformed into a radial representation. Only possible for some layouts. Defaults to FALSE. Required for
{ggraph}compatibility.- times
Maximum number of iterations, where appropriate. Required for
{ggraph}compatibility, and ignored by the layouts that do not iterate.- rank
Deprecated. Use
ranksinstead, which now takes a node attribute as well as a method.