I'd love to see a separate, dedicated package bringing spatial
functionalities to ggplot2 - this is such a great tool. However, it
seems to me that a significant problem when using ggplot2 is the lack
of geom dedicated to raster data.
My experience is you can't really deal with big rasters using
geom_tile, it takes too much memory. I guess the development of a
geom_raster is necessary to fully mimic spplot() functionalities - no
idea how demanding an effort would that be.
Pierre
2010/12/15 Roger Bivand <roger.biv...@nhh.no>:
> On Wed, 15 Dec 2010, Paul Hiemstra wrote:
>
>> Hi people,
>>
>> I posted a similar question to the ggplot2 mailing list and with their
>> help and a lot of tinkering I got a well working function to add a scalebar
>> to a ggplot plot. I could add the function to automap, but is there another
>> package which would be more appropraite, e.g. sp (Roger?)?
>
> Paul,
>
> If it was added to sp, sp would depend on ggplot2 and its dependencies,
> which are quite extensive, and include a circularity, because ggplot2
> suggests maptools, which in turn depends on sp. Consequently, sp is not a
> good idea. It might even make sense to split sp into sp with just classes
> and methods, and spViz for vizualisation methods, but changing things now is
> a bit late!
>
> It will be cleaner to try to establish the mapping functionality that uses
> ggplot2 and sp as a separate package. Maybe Hadley would see this as a
> sensible development. There are already two supplements to ggplot2 on
> R-forge, but both moribund, I think, which suggests that this needs thinking
> through.
>
> Roger
>
>>
>> cheers,
>> Paul
>>
>> ps: new version of code here:
>>
>> makeNiceNumber = function(num, num.pretty = 1) {
>> # Rounding provided by code from Maarten Plieger
>> return((round(num/10^(round(log10(num))-1))*(10^(round(log10(num))-1))))
>> }
>>
>> createBoxPolygon = function(llcorner, width, height) {
>> relativeCoords = data.frame(c(0, 0, width, width, 0), c(0, height,
>> height, 0, 0))
>> names(relativeCoords) = names(llcorner)
>> return(t(apply(relativeCoords, 1, function(x) llcorner + x)))
>> }
>>
>> addScaleBar = function(ggplot_obj, spatial_obj, attribute, addParams =
>> list()) {
>> addParamsDefaults = list(noBins = 5, xname = "x", yname = "y", unit =
>> "m", placement = "bottomright",
>> sbLengthPct = 0.3, sbHeightvsWidth = 1/14)
>> addParams = modifyList(addParamsDefaults, addParams)
>>
>> range_x = max(spatial_obj[[addParams[["xname"]]]]) -
>> min(spatial_obj[[addParams[["xname"]]]])
>> range_y = max(spatial_obj[[addParams[["yname"]]]]) -
>> min(spatial_obj[[addParams[["yname"]]]])
>> lengthScalebar = addParams[["sbLengthPct"]] * range_x
>> ## OPTION: use pretty() instead
>> widthBin = makeNiceNumber(lengthScalebar / addParams[["noBins"]])
>> heightBin = lengthScalebar * addParams[["sbHeightvsWidth"]]
>> lowerLeftCornerScaleBar = c(x = max(spatial_obj[[addParams[["xname"]]]])
>> - (widthBin * addParams[["noBins"]]),
>> y = min(spatial_obj[[addParams[["yname"]]]]))
>>
>> scaleBarPolygon = do.call("rbind", lapply(0:(addParams[["noBins"]] - 1),
>> function(n) {
>> dum = data.frame(createBoxPolygon(lowerLeftCornerScaleBar + c((n *
>> widthBin), 0), widthBin, heightBin))
>> if(!(n + 1) %% 2 == 0) dum$cat = "odd" else dum$cat = "even"
>> return(dum)
>> }))
>> scaleBarPolygon[[attribute]] = min(spatial_obj[[attribute]])
>> textScaleBar = data.frame(x =
>> lowerLeftCornerScaleBar[[addParams[["xname"]]]] +
>> (c(0:(addParams[["noBins"]])) * widthBin),
>> y =
>> lowerLeftCornerScaleBar[[addParams[["yname"]]]],
>> label = as.character(0:(addParams[["noBins"]]) *
>> widthBin))
>> textScaleBar[[attribute]] = min(spatial_obj[[attribute]])
>>
>> return(ggplot_obj +
>> geom_polygon(data = subset(scaleBarPolygon, cat == "odd"), fill =
>> "black", color = "black", legend = FALSE) +
>> geom_polygon(data = subset(scaleBarPolygon, cat == "even"), fill =
>> "white", color = "black", legend = FALSE) +
>> geom_text(aes(label = label), color = "black", size = 6, data =
>> textScaleBar, hjust = 0.5, vjust = 1.2, legend = FALSE))
>> }
>>
>> library(ggplot2)
>> library(sp)
>>
>> data(meuse)
>> data(meuse.grid)
>> ggobj = ggplot(aes(x = x, y = y, color = zinc), data = meuse) +
>> geom_point()
>> # Make sure to increase the graphic device a bit
>> addScaleBar(ggobj, meuse, "zinc", addParams = list(noBins = 5))
>>
>>
>> On 11/18/2010 09:12 PM, Paul Hiemstra wrote:
>>>
>>> Dear list,
>>>
>>> A common addition to any spatial plot are a north arrow and a scale bar.
>>> I've searched online for a straightforward way to add those to a ggplot
>>> plot. I then decided to give a go myself. A crude first attempt for an
>>> automatic scalebar addition function is listed below. The example works for
>>> the meuse dataset, but a second with a different dataset did yield good
>>> results.
>>>
>>> My question to you is: is there anyone who has some good tips / example
>>> code to add a north arrow and a scalebar to a ggplot image. Any expansions
>>> on the code below are also welcome.
>>>
>>> cheers,
>>> Paul
>>>
>>> ps Some info on my system is listed at the very bottom
>>>
>>> library(sp)
>>> library(ggplot2)
>>>
>>> data(meuse)
>>> data(meuse.grid)
>>>
>>> string.length = function(s) {
>>> # browser()
>>> if(!is.character(s)) s = as.character(s)
>>> length(strsplit(s, "")[[1]])
>>> }
>>>
>>> makeNiceNumber = function(num, num.pretty = 1) {
>>> noNumbers = string.length(as.character(round(num)))
>>> return(round(num / 10^(noNumbers - num.pretty)) * 10^(noNumbers -
>>> num.pretty))
>>> }
>>>
>>> makeScaleBar = function(obj, plotname, xname = "x", yname = "y", unit =
>>> "m", placement = "bottomright") {
>>> # browser()
>>> range_x = max(obj[[xname]]) - min(obj[[xname]])
>>> range_y = max(obj[[yname]]) - min(obj[[yname]])
>>> if(placement == "bottomright") {
>>> xcoor.max = makeNiceNumber(max(obj[[xname]]) - (0.05 *range_x ),
>>> string.length(round(max(obj[[xname]]))) - string.length(round(0.3 *
>>> range_x)))
>>> xcoor.min = makeNiceNumber(max(obj[[xname]]) - (0.5 *range_x ),
>>> string.length(round(max(obj[[xname]]))) - string.length(round(0.3 *
>>> range_x)))
>>> ycoor = min(obj[[yname]]) + (0.05 * range_y)
>>> } else {
>>> xcoor.min = makeNiceNumber(max(obj[[xname]]) - (0.95 *range_x ),
>>> string.length(round(max(obj[[xname]]))) - string.length(round(0.3 *
>>> range_x)))
>>> xcoor.max = makeNiceNumber(max(obj[[xname]]) - (0.5 *range_x ),
>>> string.length(round(max(obj[[xname]]))) - string.length(round(0.3 *
>>> range_x)))
>>> ycoor = min(obj[[yname]]) + (0.95 * range_y)
>>> }
>>> scalebar.data = data.frame(x = c(xcoor.max, xcoor.min), y = ycoor, lbl =
>>> c(paste(xcoor.max - xcoor.min, unit), 0))
>>> scalebar.data[[plotname]] = min(obj[[plotname]])
>>> return(list(geom_path(aes(x = x, y = y), data = scalebar.data, lwd = 2,
>>> color = "black"),
>>> geom_text(aes(x = x, y = y, label = lbl), data = scalebar.data,
>>> vjust = 1.3)))
>>> }
>>>
>>> sb = makeScaleBar(meuse.grid, "dist", placement = "topright")
>>> ggplot(aes(x = x, y = y, fill = dist), data = meuse.grid) + geom_tile()
>>> + sb[[1]] + sb[[2]]
>>>
>>> R version 2.12.0 (2010-10-15)
>>> Platform: i486-pc-linux-gnu (32-bit)
>>>
>>> locale:
>>> [1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C
>>> [3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8
>>> [5] LC_MONETARY=C LC_MESSAGES=en_US.UTF-8
>>> [7] LC_PAPER=en_US.UTF-8 LC_NAME=C
>>> [9] LC_ADDRESS=C LC_TELEPHONE=C
>>> [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
>>>
>>> attached base packages:
>>> [1] grid stats graphics grDevices utils datasets methods
>>> [8] base
>>>
>>> other attached packages:
>>> [1] ggplot2_0.8.7 digest_0.4.2 reshape_0.8.3 plyr_0.1.9 proto_0.3-8
>>> [6] sp_0.9-62
>>>
>>> loaded via a namespace (and not attached):
>>> [1] lattice_0.19-13
>>>
>>> hiems...@fg-113:~$ uname -a
>>> Linux fg-113 2.6.32-21-generic #32-Ubuntu SMP Fri Apr 16 08:10:02 UTC
>>> 2010 i686 GNU/Linux
>>>
>>
>>
>>
>
> --
> Roger Bivand
> Economic Geography Section, Department of Economics, Norwegian School of
> Economics and Business Administration, Helleveien 30, N-5045 Bergen,
> Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
> e-mail: roger.biv...@nhh.no
>
> _______________________________________________
> R-sig-Geo mailing list
> R-sig-Geo@r-project.org
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>
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