[R-sig-Geo] Can you query points with a polygon?
Christoph Hofer
christoph.hofer at env.ethz.ch
Wed Dec 13 13:22:43 CET 2006
Hello Kenneth
In the sp package you find the function "point.in.polygon".
Christoph
Am 13.12.2006 um 06:24 schrieb Mulholland, Tom:
> Yes there is more than one. I can't remember when I made the
> decision but I recall doing some speed tests and I picked
> inside.owin in the spatstat package. I think splancs and spatial
> might have their own versions as well. The overlay function in sp
> works. I think I found this too slow for what I was doing at the
> time. I haven't revisited this recently so it may be worth your
> while checking out the variations.
>
> Tom
>
>> -----Original Message-----
>> From: r-sig-geo-bounces at stat.math.ethz.ch
>> [mailto:r-sig-geo-bounces at stat.math.ethz.ch]On Behalf Of Pierce, Ken
>> Sent: Wednesday, 13 December 2006 1:56 PM
>> To: r-sig-geo at stat.math.ethz.ch
>> Subject: [R-sig-Geo] Can you query points with a polygon?
>>
>>
>> If I have a set of points from a shapefile (or generated in R) and a
>> polygon from a shapefile, can I use the polygon to select the points
>> that fall within it? One of the many packages must do it but I can't
>> seem to figure which one.
>>
>> Thanks,
>>
>> Kenneth B. Pierce Jr.
>> Research Ecologist
>> Landscape Ecology, Modeling, Mapping and Analysis Team
>> PNW Research Station - USDA-FS
>> 3200 SW Jefferson Way, Corvallis, OR 97331
>> ken.pierce at oregonstate.edu
>> 541 750-7393
>> http://www.fsl.orst.edu/lemma/gnnfire
>>
>>
>>
>>
>>
>> -----Original Message-----
>> From: r-sig-geo-bounces at stat.math.ethz.ch
>> [mailto:r-sig-geo-bounces at stat.math.ethz.ch] On Behalf Of
>> r-sig-geo-request at stat.math.ethz.ch
>> Sent: Monday, December 11, 2006 3:00 AM
>> To: r-sig-geo at stat.math.ethz.ch
>> Subject: R-sig-Geo Digest, Vol 40, Issue 9
>>
>> Send R-sig-Geo mailing list submissions to
>> r-sig-geo at stat.math.ethz.ch
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>> or, via email, send a message with subject or body 'help' to
>> r-sig-geo-request at stat.math.ethz.ch
>>
>> You can reach the person managing the list at
>> r-sig-geo-owner at stat.math.ethz.ch
>>
>> When replying, please edit your Subject line so it is more
>> specific than
>> "Re: Contents of R-sig-Geo digest..."
>>
>>
>> Today's Topics:
>>
>> 1. Re: project the lat./long. to x/y (zhijie zhang)
>>
>>
>> ---------------------------------------------------------------------
>> -
>>
>> Message: 1
>> Date: Mon, 11 Dec 2006 09:05:44 +0800
>> From: "zhijie zhang" <epistat at gmail.com>
>> Subject: Re: [R-sig-Geo] project the lat./long. to x/y
>> To: Roger.Bivand at nhh.no
>> Cc: r-sig-geo at stat.math.ethz.ch
>> Message-ID:
>> <2fc17e30612101705k1c06bef5of751d5764dd1d360 at mail.gmail.com>
>> Content-Type: text/plain
>>
>> *Dear Roger Bivand* ,
>> Your suggestions are very good, which gives me a general
>> method to do
>> projections.
>> Thanks.
>>
>>
>> On 12/6/06, Roger Bivand <Roger.Bivand at nhh.no> wrote:
>>>
>>> On Wed, 6 Dec 2006, zhijie zhang wrote:
>>>
>>>> Dear friends,
>>>> I had a point pattern dataset, whose locations was defined
>>> by lat./long..
>>>> In the past, I used ARCGIS to specify its coordinate
>> system and the
>>>> projection method, now i want to do it in R. I don't know
>> how to do
>>>> it, because it needs me to specify the *Geographic
>> Coordinate System
>>
>>>> and the Projected Coordinate System.* Maybe i mistake the
>>>> information in ARCGIS
>>> and
>>>> only the projection method need to be specified because of my poor
>>> knwledge
>>>> on coordiante systems.
>>>
>>> Coordinate systems are unusually difficult to understand for
>> everybody!
>>>
>>> In rgdal:
>>>
>>> EPSG <- make_EPSG()
>>> EPSG[grep("Xian", EPSG$note), 1:2]
>>>
>>> gives a list of the known projections including "Xian",
>>>
>>> among which:
>>>
>>> CRS("+init=epsg:2384")
>>>
>>> looks promising. The a= and b= specify the ellipsoid used,
>> but I have
>>> not been able to find an authority to confirm that it is
>> D_Xian_1980.
>>> One way to check would be to take a long/lat value in WGS84
>> (for known
>>
>>> datum) and convert it to the target projection in both
>> ArcGIS and with
>>
>>> spTransform() in rgdal, and see how far they differ. I do not see
>>> anything helpful in http://www.asprs.org/resources/GRIDS -
>> referenced
>>> on the make_EPSG help page, which is often a good authority, so you
>>> may need to double-check with local sources.
>>>
>>> The way to go would be to make your (point?) data set into
>> a Spatial*
>>> object with a projection argument like CRS("+proj=longlat
>>> +ellps=WGS84") if the ellipsoid is correct, and use
>> spTransform to get
>>
>>> to the Gauss_Kruger Xian datum representation.
>>>
>>> Roger
>>>
>>> PS. Yes, the Windows binary of the rgdal version you give below was
>>> built on R 2.4.0 (you are on Windows?). You need to
>> download a Windows
>>
>>> binary package manually from
>>> http://cran.r-project.org/bin/windows/contrib/
>>> (there is a 0.4-12 version for R 2.3); the same may apply to other
>>> packages.
>>>
>>>>
>>>> ---------------------------------------------------The
>> information
>>>> in
>>> ARCGIS
>>>> after projecting the dataset-------
>>>> Geometry Type: Point
>>>>
>>>> *Geographic Coordinate System:* #specify the coordinate system
>>>> GCS_Xian_1980
>>>> Datum: D_Xian_1980
>>>> Prime Meridian: 0
>>>>
>>>> *Projected Coordinate System:* Xian_1980_3_Degree_GK_CM_117E
>> #specify
>>> the
>>>> projection method
>>>> Projection: Gauss_Kruger
>>>> False_Easting: 500000.00000000
>>>> False_Northing: 0.00000000
>>>> Central_Meridian: 117.00000000
>>>> Scale_Factor: 1.00000000
>>>> Latitude_Of_Origin: 0.00000000
>>>> Linear Unit: Meter (1.000000)
>>>>
>>>
>> ---------------------------------------------------------------------
>> -
>>> ------------------------------------------------------
>>>> mapproject(x, y, projection="", parameters=NULL,
>>> orientation=NULL) *#only
>>>> allows us to define the projected coordinate system Anybody knows
>>>> how to finish it in R? Maybe rgdal() can it, but it's a
>>> liitle
>>>> difficult for me*.
>>>>
>>>> *Example of my dataset:*
>>>>
>>>> ID CLASS SOILTEM AIRTEM GHEIGHT H *LAT LONG*
>>>> 1 1 19 20 50 30.61688 117.4140
>>>> 2 1 19 21 65 30.61686 117.4140
>>>> 3 2 20 22 55 30.61680 117.4139
>>>> 4 3 20 26 10 30.61675 117.4139
>>>> 5 4 20 23 75 30.61679 117.4140
>>>> 6 1 21 21 55 30.61685 117.4141
>>>>
>>>> BTW, when i load the package rgdal, the following errors
>>>> appear,*where
>>> is
>>>> the wrong*? Does it mean i need to use the R2.4.0 version?
>>>> error in load(dataFile, ns) : ReadItem
>> uncorrect：no class 25
>>>> Warning message:
>>>> package'rgdal'is build with R2.4.0
>>>> error: package'rgdal' R's input code fail
>>>> error: 'rgdal'package/name space load fail，
>>>> -------------------------------package information
>>>> ----------------------------
>>>> R : Version 2.3.1 (2006-06-01)
>>>> rgdal_0.5-1
>>>> ---------------------------------------------
>>>>
>>>>
>>>
>>> --
>>> 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
>>>
>>>
>>
>>
>> --
>> With Kind Regards,
>>
>> oooO:::::::::
>> (..):::::::::
>> :\.(:::Oooo::
>> ::\_)::(..)::
>> :::::::)./:::
>> ::::::(_/::::
>> :::::::::::::
>> [*************************************************************
>> **********
>> ]
>> Zhi Jie,Zhang ,PHD
>> Tel:86-21-54237149 epistat at gmail.com
>> Dept. of Epidemiology,school of public health,Fudan University
>> Address:No. 138 Yi Xue Yuan Road,Shanghai,China
>> Postcode:200032
>> [*************************************************************
>> **********
>> ]
>> oooO:::::::::
>> (..):::::::::
>> :\.(:::Oooo::
>> ::\_)::(..)::
>> :::::::)./:::
>> ::::::(_/::::
>> :::::::::::::
>>
>> [[alternative HTML version deleted]]
>>
>>
>>
>> ------------------------------
>>
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo at stat.math.ethz.ch
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>
>>
>> End of R-sig-Geo Digest, Vol 40, Issue 9
>>
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo at stat.math.ethz.ch
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>
>
> _______________________________________________
> R-sig-Geo mailing list
> R-sig-Geo at stat.math.ethz.ch
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
More information about the R-sig-Geo
mailing list