[R-sig-Geo] Overlaying SpatialLines by SpatialPolygons

[Roger Bivand]

On Wed, 8 Jun 2011, Mathieu Rajerison wrote:

> Hi,
>
>
> First, thanks to all. It's the first time I use rgeos.
>
> I finally managed to get a layer of roads (routes.bdc object) that are the
> result of the intersection between roads and cities (bdc object).
>
> But the problem now is that some intersected roads are not considered being
> contained in any of the cities, although they should be, as the result of an
> intersection. I put two images of them as attached files (city contours in
> light orange, roads in blue, and some selected roads in yellow)
>
> http://hpics.li/750b6bf
> http://hpics.li/578ab3d

What is needed is a reproducible example, so that the classes of the 
output objects become evident. Can you provide such an example with 
publically available data, or put a relevant data subset on a link?

Roger

>
> Here is the code, for the moment:
> ####
> library(rgeos)
>
> pls <- slot(bdc, "polygons")
> pls1 <- lapply(pls, checkPolygonsHoles)
> slot(bdc, "polygons") <- pls1
>
> routes.bdc = gIntersection(routes, bdc)
>
> routes.bdc = slot(routes.bdc, "lineobj")
>
> bdc.contains = gContains(bdc, routes.bdc, byid=TRUE)
>
> nbdc = apply(bdc.contains, 1, function(x) as.numeric(which(x)))
>
> apply(bdc.contains, 1, function(x) any(x))
> ###
>
> apply(bdc.contains, 1, function(x) any(x))
> mentions many FALSE values which indicate that some roads are not contained
> in any city...(?)
>
>
> Any help would be greatly appreciated!
>
> Thanks again
>
> 2011/6/7 Roger Bivand <Roger.Bivand at nhh.no>
>
>> On Tue, 7 Jun 2011, Mathieu Rajerison wrote:
>>
>>  Thanks for the answer!
>>>
>>> I think I surely have to use gIntersection then gLength for this purpose
>>>
>>> I've tried gIntersection like this:
>>> routes2 = gIntersection(routes, bdc)
>>>
>>> But I get the following message:
>>> Erreur dans createPolygonsComment(p) :
>>>  rgeos_PolyCreateComment: orphaned hole, cannot find containing polygon
>>> for
>>> hole at index 1
>>>
>>> Do you have an idea why I get this message and how to correct it?
>>>
>>
>> The polygon object is malformed, and at least one polygon claims only to be
>> an interior ring, which is impossible. You need to look at how you are
>> creating your SpatialPolygons object, and possibly use checkPolygonsHoles()
>> in maptools to repair damaged objects. Typically running:
>>
>> library(maptools)
>> pls <- slot(bdc, "polygons")
>> pls1 <- lapply(pls, checkPolygonsHoles)
>> slot(bdc, "polygons") <- pls1
>>
>> may help. As Colin says, posting a link to the polygons object, and to code
>> used to create it, may be helpful.
>>
>> Roger
>>
>>
>>>
>>>
>>> 2011/6/7 Roman Lu??trik <roman.lustrik at gmail.com>
>>>
>>>  Package rgeos has all sorts of functions that might come handy.
>>>>
>>>> Cheers,
>>>> Roman
>>>>
>>>>
>>>>
>>>> On Tue, Jun 7, 2011 at 6:13 PM, Mathieu Rajerison <
>>>> mathieu.rajerison at gmail.com> wrote:
>>>>
>>>>  Hi,
>>>>>
>>>>>
>>>>> I have a SpatialLines object representing roads and a SpatialPolygons
>>>>> object
>>>>> containing cities.
>>>>>
>>>>> I'd like to know how to overlay a SpatialLines object by
>>>>> aSpatialPolygons
>>>>> object.
>>>>>
>>>>> I'd like to know the total distance of roads that cover each of my
>>>>> cities.
>>>>>
>>>>> Is it possible?
>>>>>
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Mathieu
>>>>>
>>>>>       [[alternative HTML version deleted]]
>>>>>
>>>>> _______________________________________________
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>>>>> R-sig-Geo at r-project.org
>>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> In God we trust, all others bring data.
>>>>
>>>>
>>>        [[alternative HTML version deleted]]
>>>
>>>
>>>
>> --
>> Roger Bivand
>> Economic Geography Section, Department of Economics, Norwegian School of
>> Economics and Business Administration, Helleveien 30, N-5045 Bergen,
>> Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
>> e-mail: Roger.Bivand at nhh.no
>>
>>
>
> 	[[alternative HTML version deleted]]
>
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no