Dear Almut,
I've done this with raster data, but not points as you are describing.
If you convert to a factor and then cut the data, it is possible to
create a KML as you are describing. Towards the end of a script that I
put together for the Manila R User Group there's some code that may help.
https://github.com/adamhsparks/Philippine_R_User_Group/tree/master
On Wed, Jul 29, 2015 at 11:12 PM, Almut Schlaich - Werkgroep Grauwe
Kiekendief <almut.schlaich at grauwekiekendief.nl
<mailto:almut.schlaich at grauwekiekendief.nl>> wrote:
Dear Dr. Hengl,
First of all, I would like to thank you and your colleagues for
the great package plotKML that I really enjoy using.
This was indeed a missing link to visualize data, in our case
tracking data, in Google Earth to easily explore them visually.
I would like to ask you a question about the possibilities to
color the points according to a variable.
In my data table I have a column with classification category
"phase" (e.g. migration, stopover, breeding, wintering etc.).
Using e.g.:
kml_layer(data,colour=phase,colour_scale=worldgrids_pal[[4]]), I
get tracks nicely colored depending on category.
But the difficulty arises when one bird has less levels of the
category than another (e.g. one bird making no stopover).
In this case the same colors are used, but for different values of
the category, just in the order of first appearance.
To easily compare tracks between individuals I would like to color
the same category always in the same color. I tried to
define the colors for each category and give the column with a
color value per point to the kml_layer function, but this
didn't work. Is it possible to determine the color of each point?
At the moment I just use the combination of kml_open, kml_layer
and kml_close to produce the output.
Unfortuntely, the much more beautiful and handy plotKML for
Space-time Trajectory Data Frames doesn't work for the
tracks since they have too many points. Could you tell me what is
the limit for this? And might it be possible for more
points in near future?
Thank you in advance for your help!
Kind regards,
Almut Schlaich
--
Almut Schlaich
Werkgroep Grauwe Kiekendief
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