Dear Frede and Ted,
What an absolutely crackerjack for somebody who was begging for such a
solution. It worked and worked awfully well.
I am grateful!
Eliza
> From: fr...@vestas.com
> To: eliza_bo...@hotmail.com; r-help@r-project.org
> Date: Mon, 24 Mar 2014 08:09:26 +0100
> Subject: RE: [R] points with-in boundaries of a map
>
> Hi Eliza
>
> I think this comes close to what you want (escaping manual work).
>
>
> library("maps")
> library("sp") ## has a point.in.polygon function
>
> ireland <- map("world", "ireland")
> map.axes()
>
> xr <- range(ireland$x, na.rm = TRUE)
> yr <- range(ireland$y, na.rm = TRUE)
> xseq <- seq(xr[1], xr[2], by = 0.1)
> yseq <- seq(yr[1], yr[2], by = 0.1)
> xy <- expand.grid(longitude = xseq, latitude = yseq)
>
> ## grid lines
> abline(v = xseq, col = "grey80", lty = 3)
> abline(h = yseq, col = "grey80", lty = 3)
>
> ## grid points
> ireland <- map("world", "ireland")
> map.axes()
> points(xy, pch = ".")
>
> ## get ireland map as polygon, only for main island
> ## map.poly not exported so use maps:::map.poly
> ## use exact to leave out Achill Island and only get main island
> ie.polygon <- maps:::map.poly("world", "Ireland", exact = TRUE, as.polygon =
> TRUE)
> ## x[1] and y[1] added to close polygon
> index <- point.in.polygon(xy$longitude, xy$latitude, c(ie.polygon$x,
> ie.polygon$x[1]), c(ie.polygon$y, ie.polygon$y[1]))
> table(index)
>
> ireland <- map("world", "Ireland", exact = TRUE) # leaving out Achill
> points(xy, pch = ".", cex = 1)
> map.axes()
> ## index: 0: outside, 1: border, 3: inside
> points(xy[index > 0,], pch = 1, col = "red", cex = 0.9)
>
> ## If you need Achill Island as well then do the same for this region also
> print(regionNames <- map("world", "ireland", plot = FALSE, namesonly = TRUE))
>
> ireland <- map("world", "Ireland:Achill Island", exact = TRUE, xlim = xr,
> ylim = yr)
>
> Yours sincerely / Med venlig hilsen
>
>
> Frede Aakmann Tøgersen
> Specialist, M.Sc., Ph.D.
> Plant Performance & Modeling
>
> Technology & Service Solutions
> T +45 9730 5135
> M +45 2547 6050
> fr...@vestas.com
> http://www.vestas.com
>
> Company reg. name: Vestas Wind Systems A/S
> This e-mail is subject to our e-mail disclaimer statement.
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>
>
> > -----Original Message-----
> > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org]
> > On Behalf Of eliza botto
> > Sent: 23. marts 2014 03:02
> > To: r-help@r-project.org
> > Subject: [R] points with-in boundaries of a map
> >
> > Dear UseRs,
> > I have a question regarding reading the coordinates within a country' map. I
> > drew map of ireland by using the following commands
> > library("maps")
> > library("mapproj")
> > map("world", "ireland")
> > map.axes()
> > You can clearly see the axis labelled. What is want to do is to draw lines
> > (both
> > vertically and horizontally ) at an interval of 0.5. Which means if x-axis
> > starts
> > from -10 then the first be on -10 and second on -9.5 and so on. Similar has
> > to
> > be the case with y-axis.
> > Afterwards I only want to read the coordinates of the point falling with in
> > the
> > boundary of ireland. I spent quite sometime while going through the
> > previous posts but couldnt find the answer.
> > Thankyou very much in advance,
> > Elisa
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide http://www.R-project.org/posting-
> > guide.html
> > and provide commented, minimal, self-contained, reproducible code.
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