[R] using identify() together with plot () and pixmap()
Friedrich.Leisch at ci.tuwien.ac.at
Tue Sep 30 11:38:34 CEST 2003
>>>>> On Tue, 30 Sep 2003 09:38:31 +0100,
>>>>> Barry Rowlingson (BR) wrote:
> Christoph Lehmann wrote:
>> warning: no point with 0.25 inches
>> pressing the right mouse button I get:
>> what is the problem here and how can I solve it?
> The problem is that there is no method for identifying points on a
> pixmap (and anyway, you are feeding identify() a matrix).
> You'll need to write an "identify.pixmapGrey" function. This would do
> something like use the 'locator()' function to get clicks on the screen,
> and then it would compute which grid cell the coordinates of those
> clicks were in. pixmap objects store enough information for you to work
> this out from the attributes - look at the 'bbox' attribute for example.
> It would make a nice addition to the pixmap library. Although one
> thing that just suprised me was that the different flavours of pixmap -
> pixmapGrey, pixmapIndexed, pixmapRGB - dont all inherit from a 'pixmap'
But they do, and class "pixmap" has the necessary geometry
information, i.e., size, bounding box and resolution of the image.
> which might make it easier to write a single identify function
> for all the types.
yes, shouldn't bbe too hard (all contributions welcome).
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