In R graphics, what is the different between plotting characters (pch) 16 and 19?

Question

I can\'t find any documentation other than mentions of \"filled\" vs \"solid\".

library(graphics)
plot.new()
points(.48, .5, pch=19)
points(.52, .5, pch=16)
         


        

Answer 1

From Hadley's new book R for Data Science: Note that there are some seeming duplicates: 0, 15, and 22 are all squares. The difference comes from the interaction of the colour and fill aesthetics. The hollow shapes (0–14) have a border determined by colour; the solid shapes (15–18) are filled with colour; the filled shapes (21–24) have a border of colour and are filled with fill.

Answer 2

This may help:

Values of pch are stored internally as integers. The interpretation is

NA_integer_: no symbol.

0:18: S-compatible vector symbols.

19:25: further R vector symbols.

26:31: unused (and ignored).

32:127: ASCII characters.

128:255 native characters only in a single-byte locale and for the symbol font. (128:159 are only used on Windows.)

-32 ... Unicode code point (where supported).

The full text is here

Answer 3

I used your code, and saving the image as svg.

When opening in Inkscape, the different is that 19 has a "stroke", that is a border. 16 does not.

Note that this is not a separate shape, but within the same shape.