creates a new UpSet set structure
name of the set
the elements of the set
the cardinality of the set, default to length(elems)
the color of the set
the set object
asSet("a", c(1, 2, 3))
#> $name
#> [1] "a"
#>
#> $type
#> [1] "set"
#>
#> $elems
#> [1] 1 2 3
#>
#> $cardinality
#> [1] 3
#>
#> $color
#> NULL
#>
#> attr(,"class")
#> [1] "upsetjs_set"