Re: [igraph] [Ask] Pie chart

[Gábor Csárdi]

You can do something like this. Most is this coming from the pie()
code, and the "circle" vertex shape in igraph:

mypie <- function(x, y, values, radius, edges=200, col=NULL, angle=45,
                  density=NULL, border=NULL, lty=NULL, init.angle=90, ...) {
  values <- c(0, cumsum(values)/sum(values))
  dx <- diff(values)
  nx <- length(dx)
  twopi <- 2 * pi
  if (is.null(col))
    col <- if (is.null(density))
      c("white", "lightblue", "mistyrose", "lightcyan",
        "lavender", "cornsilk")
    else par("fg")
  col <- rep(col, length.out = nx)
  border <- rep(border, length.out = nx)
  lty <- rep(lty, length.out = nx)
  angle <- rep(angle, length.out = nx)
  density <- rep(density, length.out = nx)
  t2xy <- function(t) {
    t2p <- twopi * t + init.angle * pi/180
    list(x = radius * cos(t2p), y = radius * sin(t2p))
  }
  for (i in 1:nx) {
    n <- max(2, floor(edges * dx[i]))
    P <- t2xy(seq.int(values[i], values[i + 1], length.out = n))
    polygon(x+c(P$x, 0), y+c(P$y, 0), density = density[i], angle = angle[i],
            border = border[i], col = col[i], lty = lty[i], ...)
  }
}

.igraph.shape.pie <- function(coords, el=NULL, v=NULL, mode=c("clip", "plot"),
                                 params, end=c("both", "from", "to")) {

  mode=match.arg(mode)
  end =match.arg(end)

  #####################################################################
  ## clipping mode, this is the same as for circle

  if (mode=="clip") {
    if (length(coords)==0) { return (coords) }

    vertex.size <- 1/200 * params("vertex", "size")

    if (end=="from") {
      phi <- atan2(coords[,4] - coords[,2], coords[,3] - coords[,1])
      vsize.from <- if (length(vertex.size)==1) {
        vertex.size
      } else {
        vertex.size[ el[,1] ]
      }
      res <- cbind(coords[,1] + vsize.from*cos(phi),
                   coords[,2] + vsize.from*sin(phi) )
    } else if (end=="to") {
      phi <- atan2(coords[,4] - coords[,2], coords[,3] - coords[,1])
      r <- sqrt( (coords[,3] - coords[,1])^2 + (coords[,4] - coords[,2])^2 )
      vsize.to <- if (length(vertex.size)==1) {
        vertex.size
      } else {
        vertex.size[ el[,2] ]
      }
      res <- cbind(coords[,1] + (r-vsize.to)*cos(phi),
                   coords[,2] + (r-vsize.to)*sin(phi) )
    } else if (end=="both") {
      phi <- atan2(coords[,4] - coords[,2], coords[,3] - coords[,1])
      r <- sqrt( (coords[,3] - coords[,1])^2 + (coords[,4] - coords[,2])^2 )
      vsize.from <- if (length(vertex.size)==1) {
        vertex.size
      } else {
        vertex.size[ el[,1] ]
      }
      vsize.to <- if (length(vertex.size)==1) {
        vertex.size
      } else {
        vertex.size[ el[,2] ]
      }
      res <- cbind(coords[,1] + vsize.from*cos(phi),
                   coords[,2] + vsize.from*sin(phi),
                   coords[,1] + (r-vsize.to)*cos(phi),
                   coords[,2] + (r-vsize.to)*sin(phi) )
    }

    res

  #####################################################################
  ## plotting mode

  } else if (mode=="plot") {
    getparam <- function(pname) {
      p <- params("vertex", pname)
      if (length(p) != 1 && !is.null(v)) {
        p <- p[v]
      }
      p
    }
    vertex.color       <- getparam("color")
    vertex.frame.color <- getparam("frame.color")
    vertex.size        <- rep(1/200 * getparam("size"), length=nrow(coords))
    vertex.pie         <- getparam("pie")
    vertex.pie.color   <- getparam("pie.color")
    vertex.pie.angle   <- getparam("pie.angle")
    vertex.pie.density <- getparam("pie.density")
    vertex.pie.lty     <- getparam("pie.lty")

    for (i in seq_len(nrow(coords))) {
      pie <- if(length(vertex.pie)==1) {
        vertex.pie
      } else {
        vertex.pie[[i]]
      }
      col <- if (length(vertex.pie.color)==1) {
        vertex.pie.color[[1]]
      } else {
        vertex.pie.color[[i]]
      }
      mypie(x=coords[i,1], y=coords[i,2], pie,
            radius=vertex.size[i], edges=200, col=col,
            angle=na.omit(vertex.pie.angle[c(i,1)])[1],
            density=na.omit(vertex.pie.density[c(i,1)])[1],
            border=na.omit(vertex.frame.color[c(i,1)])[1],
            lty=na.omit(vertex.pie.lty[c(i,1)])[1])
    }
  }
}

###########

library(igraph)
unlockBinding(".igraph.shapes", asNamespace("igraph"))
unlockBinding("i.default.values", asNamespace("igraph"))

shapes <- igraph:::.igraph.shapes
defaults <- igraph:::i.default.values

shapes[["pie"]] <- .igraph.shape.pie
defaults$vertex[["pie"]] <- 1
defaults$vertex[["pie.color"]] <- list(c("white", "lightblue", "mistyrose",
                                         "lightcyan", "lavender", "cornsilk"))
defaults$vertex[["pie.angle"]] <- 45
defaults$vertex[["pie.density"]] <- -1
defaults$vertex[["pie.lty"]] <- 1

assign(".igraph.shapes", shapes, asNamespace("igraph"))
assign("i.default.values", defaults, asNamespace("igraph"))

############

An then you can use it as

g <- graph.ring(10)
pie <- lapply(1:10, function(x) sample(1:10,3))
plot(g, vertex.shape="pie", vertex.pie=pie, vertex.frame.color="white",
     vertex.label=NA, vertex.pie.color=list(heat.colors(5)),
     vertex.size=seq(10,30,length=10))

Gabor

On Fri, Oct 15, 2010 at 10:08 PM, Choi <address@hidden> wrote:
> Thanks for replying.
> Right. I need to replace vertices with pies in the graph plotting.
> Since my network data (with known communities) will be divided into lots of
> partitions with different algorithms, I need an automatic way to plot these
> partitions.
> How can I define pie-chart as the vertex in plot(graph)?
>
> On Sat, Oct 16, 2010 at 3:44 AM, Gábor Csárdi <address@hidden> wrote:
>>
>> You can draw pie charts in R of course, see e.g.
>> http://www.statmethods.net/graphs/pie.html
>>
>> But what does this have to do with communities? The pie charts in the
>> PDF are based on external information as I understand. You can do such
>> a plot, either with R igraph and defining new vertex shapes, or just
>> using the pie and segments R functions directly, without using the
>> igraph plotting at all.
>>
>> Gabor
>>
>> On Fri, Oct 15, 2010 at 9:17 PM, Choi <address@hidden> wrote:
>> > Is there any (easy) way to plot those pie charts for community
>> > detection?
>> >
>> > Example of pie chart, see
>> > http://people.maths.ox.ac.uk/~porterm/papers/congposter.pdf
>> >
>> > _______________________________________________
>> > igraph-help mailing list
>> > address@hidden
>> > http://lists.nongnu.org/mailman/listinfo/igraph-help
>> >
>> >
>>
>>
>>
>> --
>> Gabor Csardi <address@hidden>     UNIL DGM
>>
>> _______________________________________________
>> igraph-help mailing list
>> address@hidden
>> http://lists.nongnu.org/mailman/listinfo/igraph-help
>
>
> _______________________________________________
> igraph-help mailing list
> address@hidden
> http://lists.nongnu.org/mailman/listinfo/igraph-help
>
>



-- 
Gabor Csardi <address@hidden>     UNIL DGM