tremmel_shape_pal(overlap = FALSE, n3alt = TRUE)n == 2.TRUE then use a solid circle, plus sign and
empty triangle, else use a solid circle, empty circle, and empty
triangle.If three symbols, then use a solid circle, empty circle, and an empty triangle. However, that set of symbols does not satisfy the requirement that each symbol should differ from the other symbols in the same feature dimension. A set of three symbols that satisfies this is a circle (curvature), plus sign (number of terminators), triangle (line orientation).
If more than three groups of data, then separate the groups into different plots.
circlefill_shape_pal,
cleveland_shape_pal,
scale_shape_circlefill,
scale_shape_cleveland,
scale_shape_tremmel