[R-sig-Geo] For each point, distance to nearest point in second dataset

[Christopher W Ryan]

See also the spatstat package, and its nncross function.

--Chris Ryan

On Thu, May 19, 2016 at 6:48 PM, Nick Eubank <nickeubank at gmail.com> wrote:
> Last note for future searchers: also suggested was the SearchTree library:
> http://stackoverflow.com/questions/37333747/for-each-point-distance-to-nearest-point-in-second-dataset-in-r
>
>
>
> On Thu, May 19, 2016 at 3:38 PM Nick Eubank <nickeubank at gmail.com> wrote:
>
>> For other's reference, that was almost right:
>>
>> To get distance from each voter to closest polling place, the syntax was:
>>
>> knn.results = knn(data=coordinates(polling.places),
>> query=coordinates(voters), k=1)
>>
>>
>>
>> On Thu, May 19, 2016 at 3:03 PM Nick Eubank <nickeubank at gmail.com> wrote:
>>
>>> Thanks Michael!
>>>
>>> Super easy context: two SpatialPointsDataFrames ("voters",
>>> "polling.places"). Each has coordinate columns "x" and "y".
>>>
>>> Is it just:
>>>
>>> library(nabor)
>>> knn(voters, query = polling.places, k=1)
>>>
>>> ?
>>>
>>> On Thu, May 19, 2016 at 2:59 PM Michael Sumner <mdsumner at gmail.com>
>>> wrote:
>>>
>>>> Use nabor package, it takes a little to learn but is crazy fast.
>>>>
>>>> Happy to show if you make a relevant example.
>>>> Mike
>>>>
>>>> On Fri, May 20, 2016, 06:42 Nick Eubank <nickeubank at gmail.com> wrote:
>>>>
>>>>> Hi All,
>>>>>
>>>>> Trying to an equivalent to the "nearest" tool in ArcGIS for two
>>>>> SpatialPointDataFrames. I can do the naive implementation by calculating
>>>>> all pairwise distances using gDistance and taking the min, but I have
>>>>> some
>>>>> huge datasets and was looking for something more efficient. (For
>>>>> example,
>>>>> here's a trick with knearneigh for points in same dataset (
>>>>>
>>>>> http://gis.stackexchange.com/questions/132384/distance-to-nearest-point-for-every-point-same-spatialpointsdataframe-in-r
>>>>> )).
>>>>>
>>>>> Any suggestions?
>>>>>
>>>>> Thanks!
>>>>>
>>>>> Nick
>>>>>
>>>>>         [[alternative HTML version deleted]]
>>>>>
>>>>> _______________________________________________
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>>>>> R-sig-Geo at r-project.org
>>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>>>
>>>> --
>>>> Dr. Michael Sumner
>>>> Software and Database Engineer
>>>> Australian Antarctic Division
>>>> 203 Channel Highway
>>>> Kingston Tasmania 7050 Australia
>>>>
>>>>
>
>         [[alternative HTML version deleted]]
>
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