Identify points in a plot, similarly to the `identify`

function
in base graphics.

```
identify3d(x, y = NULL, z = NULL, labels = seq_along(x), n = length(x),
plot = TRUE, adj = c(-0.1, 0.5), tolerance = 20,
buttons = c("right", "middle"))
```

## Arguments

- x, y, z
coordinates of points in a scatter plot. Alternatively, any
object which defines coordinates (see `xyz.coords`

)
can be given as `x`

, and `y`

and `z`

left missing.

- labels
an optional character vector giving labels for the
points. Will be coerced using `as.character`

, and
recycled if necessary to the length of `x`

.

- n
the maximum number of points to be identified.

- plot
logical: if `plot`

is `TRUE`

, the labels are
printed near the points and if `FALSE`

they are omitted.

- adj
numeric vector to use as `adj`

parameter to
`text3d`

when plotting the labels.

- tolerance
the maximal distance (in pixels)
for the pointer to be ‘close enough’ to a point.

- buttons
a length 1 or 2 character vector giving the buttons
to use for selection and quitting.

## Details

If `buttons`

is length 1, the user can quit by reaching `n`

selections, or by hitting the
escape key, but the result will be lost if escape is used.

## Value

A vector of selected indices.