renderGraph            package:Rgraphviz            R Documentation

_R_e_n_d_e_r _a _l_a_i_d _o_u_t _g_r_a_p_h _o_b_j_e_c_t

_D_e_s_c_r_i_p_t_i_o_n:

     This method uses the 'renderInfo' slot of a graph object to render
     it on a plotting device. The graph must have been laid out using
     the 'layoutGraph' function before.

_U_s_a_g_e:

     ## S4 method for signature 'graph':
     renderGraph(x, drawNodes, drawEdges, graph.pars)

_A_r_g_u_m_e_n_t_s:

       x: An object derived from class 'graph'

drawNodes: A function that is used for the node rendering. The details
          of its API are still undecided, so far the input to the
          function is the (laid out) graph object. Defaults to
          'renderNodes', which is not exported in the name space (type
          'Rgraphviz:::renderNodes' to see the function definition).
          This default function knows how to draw node shapes of type
          'box', 'rectangle', 'ellipse', 'plaintext', 'circle' and
          'triangle'. In addition, an arbitrary user-defined function
          can be passed on to draw the node. This function needs to be
          able to deal with the following arguments: a two-by-two
          matrix of the bounding box for the respective node, and
          'labelX', 'labelY', 'fill', 'col', 'lwd', 'lty', 'textCol',
          'style', 'label' and 'fontsize', which are all defined by the
          layout algorithm or are graphical 'nodeRenderInfo'
          parameters. 

drawEdges: A function that is used for the edge rendering. Defaults to
          'renderEdges'. Currently, this function can draw different
          types of arrowheads: 'open', 'normal', 'dot', 'odot', 'box',
          'obox', 'tee', 'diamond', 'odiamond' and 'none'. In addition,
          a user-defined function can be passed as 'arrowhead' or
          'arrowtail' parameters which needs to be able to deal with 4
          arguments: A list of xy coordinates for the center of the
          arrowhead, and the graphical parameters 'col', 'lwd' and
          'lty'. 

graph.pars: A list of rendering parameters to use as defaults.
          Parameters that have been explicitely set using
          'nodeRenderInfo', 'edgeRenderInfo' or 'graphRenderInfo' take
          precendence. If not explicitely supplied, the value of a call
          to 'graph.par' is used. This design allows to set
          session-wide defaults. 

     ...: further arguments

_D_e_t_a_i_l_s:

     This method can render graph objects that have previously been
     laid out using the function 'layoutGraph'. The details for user
     defined node drawing remain to be decided.

_V_a_l_u_e:

     An object derived from class 'graph' with information about the
     coordinates of the nodes in the coordinate system of the plotting
     device added to the 'renderInfo' slot.

_A_u_t_h_o_r(_s):

     Florian Hahne

_S_e_e _A_l_s_o:

     'layoutGraph', 'link[graph]{nodeRenderInfo}',
     'link[graph]{edgeRenderInfo}', 'link[graph]{graphRenderInfo}',

_E_x_a_m_p_l_e_s:

     library(graph)
     set.seed(123)
     V <- letters[1:5]
     M <- 1:2
     g1 <- randomGraph(V, M, 0.5)
     edgemode(g1) <- "directed"
     x <- layoutGraph(g1)
     renderGraph(x)

     ## one of Graphviz's additional layout algorithms
     x <- layoutGraph(g1, layoutType="neato")
     renderGraph(x)

     ## some tweaks to Graphviz's node and edge attributes,
     ## including a user-defined arrowhead and node shape functions.
     myArrows <- function(x, ...)
     {
     for(i in 1:4)
     points(x,cex=i)
     }

     myNode <- function(x, col, fill, ...)
     symbols(x=mean(x[,1]), y=mean(x[,2]), thermometers=cbind(.5, 1,
     runif(1)), inches=0.5,
     fg=col, bg=fill, add=TRUE)

     eAtt <- list(arrowhead=c("a~b"=myArrows, "b~d"="odiamond", "d~e"="tee"))
     nAtt <- list(shape=c(d="box", c="ellipse", a=myNode))
     edgemode(g1) <- "directed"
     x <- layoutGraph(g1, edgeAttrs=eAtt, nodeAttrs=nAtt, layoutType="neato")
     renderGraph(x)

