[R] [EXT] Re: Linestring values to vector

[David Stevens]

The way I did this recently is to look into the .dbf file that comes 
with the shapefile group from ESRI or your feature site, and search the 
feature names for the one I want. This gives you an index to use to 
search for the feature in the actual shapefile. Then, once the shapefile 
is loaded into R using the shapefiles package, you can get the vectors 
of polygon vertices by

lr <- shapefiles::read.shapefile(myFile) # lr is the shapefile object

sfs <- lr$shp[myIndex] #sfs will be a list and the first element is the 
geometry
sfp <- sfs[[1]]$points #sfp is the set of X and Y vertices

lines(sfp$X],sfp$Y,col='red',lwd=2)

David

David K Stevens, PhD, PE, Professor
Civil and Environmental Engineering
Utah Water Research Laboratory
Utah State University
8200 Old Main Hill
Logan, UT 84322-8200
david.stevens using usu.edu
(435) 797-3229 (office)

On 10/21/2022 12:01 PM, Jeff Newmiller wrote:
> As the Posting Guide would have warned you, you will probably have better luck asking this kind of question on the R-sig-geo mailing list.
>
> On October 21, 2022 10:45:30 AM PDT, Nick Wray <nickmwray using gmail.com> wrote:
>> Hello I have downloaded a large shapefile dataset of UK rivers and I want
>> to isolate (as an ordinary R string) the LINESTRING values for particular
>> lines, corresponding to rivers
>> Looking at the first line I can isolate the geometry by
>>
>> Hello I have downloaded a large shapefile dataset of UK rivers and I want
>> to isolate (as an ordinary R string) the LINESTRING values for particular
>> lines, corresponding to rivers
>>
>> Looking at the first line I can isolate the geometry by
>>
>>
>>
>> st_geometry(rivers[1,8])
>>
>>
>>
>> Geometry set for 1 feature
>> Geometry type: LINESTRING
>> Dimension:     XYZ
>> Bounding box:  xmin: 462010.6 ymin: 1213039 xmax: 462306.5 ymax: 1213199
>> z_range:       zmin: 0 zmax: 0
>> Projected CRS: OSGB 1936 / British National Grid
>>
>> LINESTRING Z (462306.5 1213048 0, 462275.4 1213...
>>
>>
>> What I need is all the values in the LINESTRING as a common or garden R
>> vector, but I cannot find a way to do this.
>>
>> Does anyone know how?  Thanks, Nick Wray
>>
>>        [[alternative HTML version deleted]]
>>
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> --
> Sent from my phone. Please excuse my brevity.
>
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