[R] how to specify point symbols in the key on a lattice dotplot

[Christopher W. Ryan]

I am making a dotplot with lattice, as follows:

dd %>% dotplot( segment ~ transit_time, groups = impact,  data = .,
               as.table = TRUE,
                pch = 16:17,
                cex = 1.8,
                scales = list(cex = 1.4),
               auto.key = TRUE)

impact is a factor with two levels.

They key shows 2 open circles, one of each color of my two
plotting symbols, one for each group. I would like the
symbols in the key to match the plotting characters in the graph: 16
(filled circle) for one group and 17 (filled triangle) for the second
group.  How would I do that? I have not had any success with supplying
arguments to auto.key, simpleKey, or key. Guess I'm not understanding
the syntax.

Thanks.

--Chris Ryan

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