CODEWITHSUNDEEP
rpolygongeospatialspatial
hubert_farnsworth
hubert_farnsworth

Reputation: 797

Can R merge latitude and longitude points to areas in spatial polygon?

I have two data frames. One is a Spatial Polygon and the other is a Spatial Points dataframe. Unfortunately I can't reproduce the entire example here but the Spatial Polygon looks like this: 

     head(electorate)
     ELECT_DIV STATE NUMCCDS ACTUAL PROJECTED POPULATION OVER_18  AREA_SQKM SORTNAME
     Adelaide    SA     318      0         0          0       0    76.0074 Adelaide
        Aston   VIC     191      0         0          0       0    99.0122    Aston
     Ballarat   VIC     274      0         0          0       0  4651.5400 Ballarat
        Banks   NSW     229      0         0          0       0    49.3189    Banks
       Barker    SA     343      0         0          0       0 63885.7100   Barker
       Barton   NSW     234      0         0          0       0    44.1112   Barton

As you can see it's the spatial polygon for the Australian electorate. The second data frame is a Spatial points dataframe with longitude and latitude for polling places. It looks like this - 

  head(ppData)
  State PollingPlaceID    PollingPlaceNm Latitude Longitude
1   ACT           8829            Barton -35.3151   149.135
2   ACT          11877          Bonython -35.4318   149.083
3   ACT          11452           Calwell -35.4406   149.116
4   ACT           8794 Canberra Hospital -35.3453   149.099
5   ACT           8761           Chapman -35.3564   149.042
6   ACT           8763          Chisholm -35.4189   149.123

My goal is to try and match each polling place (PollingPlaceID) to the appropriate electoral division (ELECT_DIV). There will be many polling places within each division. It's no problem to plot them over each other. It seems only natural that R will also let me add a new vector to my polling place data frame (ppData) which assigns each polling place the electorate (ELECT_DIV) it falls within.

I know I can extract the coordinates for each ELECT_DIV from electorate with coordinates(electorate) but I'm not sure that actually helps. Any advice?

Upvotes: 4

Views: 3460

Answers (1)

Simon O'Hanlon
Simon O'Hanlon

Reputation: 59970

You need over from sp and you can use it like this:

require( sp )
ID <- over( SpatialPoints( ppData ) , electorate )
ppData@data <- cbind( ppData@data , ID )

This returns a data.frame where each row relates to the first argument (each of your polling points) and is the data from the polygon that the point fell in. You can just cbind them afterwards and you now have the polygon data that relates to each point.

Upvotes: 3

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