Add polygon search

[AugustT]

The API has a polygon field that I don't currently make use of. I cannot remember why but I should look into it again.

First the user should be able to submit the polygon as a WKT string

"POLYGON ((-0.11450148172820968 54.130864525842412, -0.11446068409490597 54.131762784280212, -0.11293115900887428 54.131738814327306, -0.11297198969343905 54.130840556676205, -0.11450148172820968 54.130864525842412))"

Second the user should be able to give a point and buffer, something like:

dt1 <- getOccurrences(tvks = "NBNSYS0000002987",
    datasets = "GA000373", 
    startYear = "1990",
    endYear = "1991",
    latlong = c(-0.1145, 54.1308),
    radius = 5000)

This can use this code internally:

createWKT <- function(latitude, longitude, radius = 5000) {

  library(sp)
  library(rgdal)
  library(rgeos)

  p <- SpatialPointsDataFrame(coords = data.frame(lon = longitude, lat = latitude),
                              data.frame(ID = 1),
                              proj4string = CRS("+proj=longlat +ellps=WGS84 +datum=WGS84"))
  stopifnot(length(p) == 1)
  cust <- sprintf("+proj=tmerc +lat_0=%s +lon_0=%s +k=1 +x_0=0 +y_0=0 +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs", 
                  p@coords[[2]], p@coords[[1]])
  projected <- spTransform(p, CRS(cust))
  buffered <- gBuffer(projected, width = radius, byid = TRUE)
  bufferedOrg <- spTransform(buffered, p@proj4string)
  writeWKT(bufferedOrg)

}

[AugustT]

The URL should look like this:

https://data.nbn.org.uk/api/taxonObservations/?polygon=POLYGON%20((-0.11450148172820968%2054.130864525842412,
%20-0.11446068409490597%2054.131762784280212,
%20-0.11293115900887428%2054.131738814327306,
%20-0.11297198969343905%2054.130840556676205,
%20-0.11450148172820968%2054.130864525842412))

Remember to use gsub to convert ' ' to a '%20'

[AugustT]

#14