The below help worked like a charm and now I've been asked for an ellipse.
No problem, I thought to myself, except for some reason my outer ring
remains a circle regardless of what I do. Inner ring is fine. Here's what
I've done.
I hope there's something stupid I forgot, but I just can't find it.
ellip.layout <- function(a,b, theta) {
cbind(a*cos(theta), -b*sin(theta))
}
males <- which(V(g)$gender == "M")
females <- which(V(g)$gender == "F")
a<- ifelse(V(g)$gender == "M",4,5)
b<- ifelse(V(V(g)$gender == "M",0.5,1)
theta <- rep.int(0, vcount(g)) #creates a blank vector
theta[males] <- (1:length(males)-1) * 2 * pi / length(males)
theta[females] <- (1:length(females)-1) * 2 * pi / length(females)
layout<- ellip.layout(a,b,theta)
plot.igraph(g, layout=layout)
I thought maybe it was squishing it so I tried different values for a and b
but that didn't help.
Thank you for your patience!
Christina
On Thu, Mar 5, 2015 at 12:00 PM, <[email protected]> wrote:
>
> Message: 1
> Date: Thu, 5 Mar 2015 12:18:11 +0100
> From: Tamas Nepusz <[email protected]>
> To: Help for igraph users <[email protected]>
> Subject: Re: [igraph] Graphing in a "polar" layout
> Message-ID: <[email protected]>
> Content-Type: text/plain; charset=us-ascii
>
> Hi Christina,
>
> igraph layouts are simply matrices with 2 columns and one row for each
> vertex,
> so the easiest is probably if you generate such a matrix yourself. If you
> want
> to place a vertex at radius r from the center with an angle of alpha (in
> radians), then you have to use the following formulae to figure out the X
> and
> Y coordinates:
>
> X = r * cos(alpha)
> Y = -r * sin(alpha)
>
> where the Y coordinate is negated only because the Y axis of the coordinate
> system of the screen is oriented from top to bottom.
>
> You haven't mentioned whether you are using igraph from R or Python and I'm
> more familar with Python, so I'll add an example in Python here:
>
> from igraph import Layout
> from math import sin, cos
>
> def polar_layout(radii, angles):
> return Layout([(r*cos(angle), -r*sin(angle)) for r, angle in
> zip(radii, angles)])
>
> The "polar_layout" function has to be called with two lists: one that
> specifies
> the radius of each vertex and one that specifies the angle of each vertex.
> It
> will then return a Layout object that can be passed to plot() as follows:
>
> layout = polar_layout(..., ...)
> plot(graph, layout=layout)
>
> All the best,
> Tamas
>
> On 02/04, Christina Pikas wrote:
> > I've got ~100 nodes assigned to various categories. I would like to end
> up
> > with nodes of one category in the center and all the other categories
> > spaced along a ring outside - like this NodeXL polar graph:
> >
> http://www.connectedaction.net/2013/03/03/how-to-plot-a-network-in-a-polar-layout-using-nodexl/
> >
> > I know about star layouts (just one node in the center?) and ring or
> circle
> > layouts.
> >
> > My plan was to find the layout coordinates for subgraphs for each group
> and
> > then copy them all over, but this is proving to be even more of a hassle
> > than I had originally thought.
> >
> > Is there an easier way?
> >
> > Thanks in advance,
> > Christina
>
> > _______________________________________________
> > igraph-help mailing list
> > [email protected]
> > https://lists.nongnu.org/mailman/listinfo/igraph-help
>
_______________________________________________
igraph-help mailing list
[email protected]
https://lists.nongnu.org/mailman/listinfo/igraph-help
