plotPieNet: Plot a graph with pie chart associated with each node
In Albluca/ElPiGraph.R: Elastic principal graph construction

Plot a graph with pie chart associated with each node

plotPieNet(X, TargetPG, GroupsLab = NULL, Nodes = NULL, Partition = NULL,
  TrimmingRadius = Inf, Graph = NULL, LayOut = "nicely",
  LayoutIter = 500, TreeRoot = numeric(), RootLevel = numeric(),
  distMeth = "manhattan", Main = "", ScaleFunction = sqrt,
  NodeSizeMult = 1, ColCat = NULL, Leg.cex = 1, Leg.pos = "bottom",
  Leg.horiz = TRUE, Arrow.size = 1, NodeLabels = NULL, LabSize = 1)

`X`	numerical 2D matrix, the n-by-m matrix with the position of n m-dimensional points
`TargetPG`	the main principal graph to plot
`GroupsLab`	string factor, a vector indicating the category of each data point
`Nodes`	integer, the vector of nodes to plot. If NULL, all the nodes will be plotted.
`Partition`	A vector associating each point to a node of the ElPiGraph. If NULL (the default), this will be computed
`TrimmingRadius`	numeric, the trimming radius to use when associting points to nodes when Partition = NULL
`Graph`	a igraph object of the ElPiGraph, if NULL (the default) it will be computed by the function
`LayOut`	the global layout of yhe final network. It can be 'tree', a tree 'circle', a closed circle 'circle_line', a line arranged as a circle 'kk', a topology generated by the Kamada-Kawai layout algorithm 'mds', a topology generated by multidimensional scaling on the node positions 'fr', a topology generated by the Fruchterman-Reingold layout algorithm 'nicely', the topology will be inferred by igraph
`LayoutIter`	numeric, the number of interation of the layout algorithm
`TreeRoot`	the id of the node to use as the root of the tree when LayOut = 'tree', multiple nodes are allowed.
`RootLevel`	numeric, the level of the root(s)
`distMeth`	the matric used to compute the distance if LayOut = 'mds'
`Main`	string, the title of the plot
`ScaleFunction`	function, a function used to scale the nuumber of points (sqrt by default)
`NodeSizeMult`	integer, an adjustment factor to control the size of the pies
`ColCat`	string vector, a vector of colors to associate to each category
`Leg.cex`	numeric, a value to adjust the size of the legend
`Leg.pos`	character, the position of the legend (see the help of the legend function)
`Leg.horiz`	boolean, should the legend be plotted in horizontal
`Arrow.size`	numeric, the size of the arrow
`NodeLabels`	character vector, the names of the nodes
`LabSize`	numeric, the size of the node labels