gtable structure element description
ggplot2, gtable, r
Solution
A few components are described in this wiki page. Basically,
grobs: list of graphical elements associated with the gtable, and to be drawn in the cells defined by the layout
layout: data.frame describing the position of each grob in a tabular layout
widths, heights: size of the rows and columns
respect: parameter indicating whether dimensions are linked (fixed aspect ratio)
colnames, name: for identification of the rows/columns
gp: global set of grid parameters, from which the grobs may inherit
vp: viewport defining where to draw the gtable on a device
Problem
If I create a gtable and look at some of the elements, I see for instance: ``` test<-data.frame(x=1:20, y=21:40, facet.a=rep(c(1,2),10), facet.b=rep(c(1,2), each=20)) p <- qplot(data=test, x=x, y=y, facets=facet.b~facet.a) # get gtable object z <- ggplot_gtable(ggplot_build(p)) > names(z) [1] "grobs" "layout" "widths" "heights" "respect" "colnames" "name" [8] "gp" "vp" > z$widths [1] 0.5lines 1grobwidth+0.5lines 0.620416666666666cm [4] 1null 0.25lines 1null [7] 0.545041666666667cm 1lines ``` Is there any detailed documentation of what the values of these elements mean with respect to the created plot? The gtable documentation only documents the functions in creating and amending gtables. The data came from a post made on July 5.