proximity.timeline: Plot a chart of a networkDynamic object in which vertices...

In ndtv: Network Dynamic Temporal Visualizations

Plot a chart of a networkDynamic object in which vertices trace out paths in time, positioned vertically so that their proximity corresponds to their relative geodesic distance at the sampled time points.

Description

This a DRAFT version of the function, parameters are likely to change. Creates a 'phase plot' chart of vertex geodesic distance proximities overtime time, with the ability to size and color the lines corresponding to each vertex with arguments similar to plot.network

Usage

proximity.timeline(nd,  start = NULL, end = NULL, time.increment = NULL,
  onsets = NULL, termini = NULL, rule='earliest', default.dist = NULL, 
  vertex.col = "#55555555", label = network.vertex.names(nd), 
  labels.at = NULL, label.cex = 1,
  vertex.cex = 2, splines = -0.2, render.edges=FALSE, grid=!render.edges, 
  edge.col='#00000055', edge.lwd=4,
  mode=c('isoMDS','sammon','cmdscale','gvNeato','MDSJ'),
  coords=NULL,
  draw.inactive=NULL, 
  spline.style=c('default','inactive.ghost','inactive.gaps',
                'inactive.ignore','color.attribute'),
  chain.direction=c('forward','reverse'),
  verbose=TRUE, ...)

Arguments

nd	a networkDynamic object to be plotted.
start	optional numeric value giving the time to start the network sampling to be passed to link{get.networks}
end	optional numeric value giving the time to end the network sampling to be passed to link{get.networks}
time.increment	optional numeric value to increment network sampling to be passed to link{get.networks}
onsets	optional numeric vector of sampling onset time points to be passed to link{get.networks}
termini	optional numeric vector of sampling terminus time points to be passed to link{get.networks}
rule	attribute aggregation rule (default 'earliest') to be passed to network.collapse
default.dist	numeric default distance parameter to space apart isolates and disconnected components. Usually defaults to square root of network size (see layout.distance)
vertex.col	either a character color value, a vector of values of length equal to the size of the network, or the name of a vertex attribute containing color values to be used to color each of the vertices splines. Note that partially transparent colors work much better than opaque colors, as it is easier to see when lines overlap. When used with spline.style='color.attribute', vertex.col can be a function with a special limited set of arguments (see Details of render.animation) which will be evaluated at the onset of each segment.
labels.at	numeric value or vector of values specifying the time(s) at which vertex labels should be plotted on the splines. If NULL (default), labels will not be drawn.
label	character vector of labels for vertices or name of vertex attribute to be expanded. Default is network.vertex.names. Labels only drawn if labels.at argument has a value.
label.cex	numeric character expansion factor for vertex labels
vertex.cex	either a numeric value, a vector of values of length equal to the size of the network, or the name of a vertex attribute containing numeric values to be used to scale the width of the lines (lwd) for each vertex.
splines	numeric. value controls how tightly the splines meet their control points. A value of 0 draws straight lines and sharp corners, values less than zero cause the spline to pass through the control point, values greater than zero will approximate the point. See the shape argument of xspline.
render.edges	logical (default FALSE). Should overlapping virtical lines corresponding to the edges be drawn between the the splines corresponding to the vertices at the time points of edge onsets?
edge.col	color value or edge attribute name to be used for the edge lines if render.edges=TRUE
edge.lwd	numeric line width value or edge attribute name to be used for the width of the edge lines if render.edges=TRUE
grid	logical. if TRUE, vertical lines in the background color will be drawn at the beginning of each time slice to make it easier to determine where on the splines the positions are actually set. Usually this is not used with render.edges
mode	name of MDS algorithm to be used. Currently one of isoMDS,sammon,cmdscale
coords	optional numeric matrix of pre-computed coordinates to be used instead of the algorithm in mode. The number of matrix rows must be equal to the network size and columns equal to number of time bins implied by other arguments)
draw.inactive	DEPRECATED. see spline.style
spline.style	options to control how vertices with inactive spells or changing attribute values should be drawn: 'inactive.ignore' ignores activity spells and draws an unbroken spline for each vertex (fastest). 'inactive.gaps' leaves gaps in the splines when vertices are inactive 'inactive.ghost' draws faint gray dotted lines under the spline so they appear in the gaps 'default' does 'inactive.ignore' if there are no gaps in encountered, otherwise 'inactive.ghost' 'color.attribute' uses the activity spells of the vertex color TEA (indicated by the vertex.col argument) to break the splines in to color segments – ignoring the the vertices activity spells
chain.direction	value of 'forward' means that the slice layouts should be computed in temporal order, with each layout initialized with the coordinates from the previous. A value of 'reverse' causes layouts to be computed in reverse temporal order (for some layouts, this will cause less spline crossing as vertices will tend to be closer to their final state).
verbose	logical, default is TRUE, in which case status messages about the computations are printed to the console, at some speed cost
...	arguments to be passed to network.collapse (via get.networks) to control how the network should be aggregated during slicing

Details

The passed network dynamic object is sliced up into a series of networks. It loops over the networks, converting each to a distance matrix based on geodesic path distance with layout.distance. The distances are fed into an MDS algorithm (specified by mode) that lays them out in one dimension: essentially trying to position them along a vertical line. The sequence of 1D layouts are arranged along a timeline, and a spline is drawn for each vertex connecting its positions at each time point. The idea is that closely-linked clusters form bands of lines that move together through the plot.

Currently,

• mode='sammon' tends to produce much equally spaced lines, making it easier to follow individual vertices, but harder to see clusters

• mode='isoMDS' does a better job with clusters, but in some layouts converges too soon and just produces straight lines,

• mode='cmdscale' does a great job with clusters, but is highly unstable (coordinates will reshuffle dramatically on nearly identical networks).

• mode='gvNeato' tries to do a 1D Graphviz neato layout (experimental) network.layout.animate.Graphviz.

• mode='MDSJ' tries a 1D network.layout.animate.MDSJ layout.

For most of the layouts it is necessary to manually adjust the default dist parameter to find a value that sufficently groups together linked clusters and spaces out isolates.

Note for RStudio users: the spline rendering seems to be much slower on RStudio's graphics device than on other graphics devices such as x11().

Value

Produces a plot with horizontal splines corresponding the vertices of the network and vertical proximities approximately proportional to geodesic distance. Invisibly returns a numeric matrix of coordinates corresponding to computed positions of each vertex at each time bin. This can be passed in via the coords argument.

Note

This is still very much a work in progress, the 1D optimization are not very stable, especially for cmdscale

Author(s)

[e-mail]

References

Some inspirational examples here: http://skyeome.net/wordpress/?p=604

See Also

See also timeline for plotting spells of vertices and edges without proximity positioning.

Examples

# use the classroom interaction dataset
data(McFarland_cls33_10_16_96)

# divide the first 20 minutes of time into
# overlapping 2.5 minute bins
# and make the lines for the instructors much larger
proximity.timeline(cls33_10_16_96,
   onsets=seq(0,20,0.5),
   termini=seq(2.5,22.5,0.5),
   vertex.cex=(cls33_10_16_96%v%'type'=='instructor')*4+1,
   labels.at=16)

# load the infection sim dataset
data(toy_epi_sim)
# render a timeline with vertices colored by infection status
# show only the first 5 timesteps
proximity.timeline(toy_epi_sim,vertex.col = 'ndtvcol',
                  spline.style='color.attribute',
                  mode='sammon',default.dist=20,
                  chain.direction='reverse',
                  start=1,end=5)

ndtv documentation built on July 4, 2024, 5:08 p.m.