Change thickness of a marker in ggplot2

Question

I am using the following code to make a map with proportional points to an outter characteristic (Total), but i would like to change the width of the marker.

Answer 1

Is it the thickness of the boundary of a hollow point that you want to change? It can be done with grid.edit from the grid package.

library(ggplot2)
library(grid)

ggplot(data = data.frame(x = 1:10, y = 1:10), aes(x=x, y=y)) + 
   geom_point(size = 10, shape = 1)

grid.force()  # To make the grobs visible to grid editing tools

grid.edit("geom_point.points", grep = TRUE, gp = gpar(lwd = seq(1, 5.5, .5)))

EDIT To get legend keys to match the points

library(ggplot2)
library(grid)
library(gtable)

p = ggplot(data = data.frame(x = 1:10, y = 1:10, c = c(rep("a", 5), rep("b", 5))), 
   aes(x=x, y=y, colour = c)) + 
   geom_point(shape = 1, size = 10)

lwd = 8   # Set line width

g = ggplotGrob(p); dev.off()  # Get the plot grob

# Get the indices for the legend: t = top, r = right, ...
indices <- c(subset(g$layout, name == "guide-box", select = t:r))

# Get the row number of the legend in the layout
rn <- which(g$layout$name == "guide-box")

# Extract the legend
legend <- g$grobs[[rn]]

# Get the legend keys
pointGrobs = which(grepl("points", legend$grobs[[1]]$grobs))

# Check them out - no line width set
# for (i in pointGrobs) str(legend$grobs[[1]]$grobs[[i]])

# Set line width
for (i in pointGrobs) legend$grobs[[1]]$grobs[[i]]$gp$lwd = lwd

# Check them out - line width set
# for (i in pointGrobs) str(legend$grobs[[1]]$grobs[[i]])

# Put the modified legend back into the plot grob
g = gtable_add_grob(g, legend, t=indices$t, l=indices$l)

# g$grobs[[4]]$children[[2]]$gp$lwd = lwd  # Alternative for setting lwd for points in the plot

grid.newpage()
grid.draw(g)

grid.force()  # To make the grobs visible to grid editing tools

grid.edit("geom_point.points", grep = TRUE, gp = gpar(lwd = lwd))