Create a rectangle filled with text - r

Question

I'd like to create a filled rectangle in R, with white text centered in the middle, and export it to png. I know the rect() function can probably do this, but every example I've seen the rectangle is printed on a plot. Is there a way to do this without the plot?
For reference, I'm building a blogdown() site and trying to create a square that looks pretty much identical to those in the Hugrid theme.

Answer 1

You can use geom_rect() to create rectangles and geom_text() to paste text into them. Modifying rectangle look (color, line size or type) in ggplot2 is easy. All you have to do is to remove default ggplot2 look with theme_classsic() and element_blank().
# Generate dummy dataset
foo <- data.frame(x1 = 1, x2 = 2, y1 = 1, y2 = 2,
text = paste(letters[1:3], letters[1:3], collapse = "\n"))
# Plot rectangle with text
library(ggplot2)
ggplot(foo) +
geom_rect(aes(xmin = x1, xmax = x2, ymin = y1, ymax = y2),
color = "black", size = 2, fill = "lightblue") +
geom_text(aes(x = x1 + (x2 - x1) / 2, y = y1 + (y2 - y1) / 2,
label = text),
size = 20) +
theme_classic() +
theme(axis.line = element_blank(),
axis.ticks = element_blank(),
axis.text = element_blank(),
axis.title = element_blank())

Answer 2

Here's a lightweight solution,
rects <- data.frame(fill = RColorBrewer::brewer.pal(5, "Pastel1"),
colour = RColorBrewer::brewer.pal(5, "Set1"),
label = paste("text", 1:5), stringsAsFactors = FALSE)
library(gridExtra)
gl <- mapply(function(f,l,c) grobTree(rectGrob(gp=gpar(fill=f, col="white",lwd=2)),
textGrob(l, gp=gpar(col=c))),
f = rects$fill, l = rects$label, c = rects$colour,
SIMPLIFY = FALSE)
grid.arrange(grobs=gl)

Answer 3

It's not quite clear from your question what exactly the sticking point is. Do you need to generate the rectangles from R (instead of, say, manually in Illustrator)? And no plot window must be shown?
All of this can be achieved. I prefer to draw with ggplot2, and the specific geoms you'd need here are geom_tile() for the rectangles and geom_text() for the text. And you can save to png without generating a plot by using ggsave().
rects <- data.frame(x = 1:4,
colors = c("red", "green", "blue", "magenta"),
text = paste("text", 1:4))
library(ggplot2)
p <- ggplot(rects, aes(x, y = 0, fill = colors, label = text)) +
geom_tile(width = .9, height = .9) + # make square tiles
geom_text(color = "white") + # add white text in the middle
scale_fill_identity(guide = "none") + # color the tiles with the colors in the data frame
coord_fixed() + # make sure tiles are square
theme_void() # remove any axis markings
ggsave("test.png", p, width = 4.5, height = 1.5)
I made four rectangles in this example. If you need only one you can just make an input data frame with only one row.