Thanks. This has been very helpful and I am very appreciative. A few more
queries I have though, if you don't mind.
Is there an easy to way to plot axes onto the png? I am trying to make an
'atlas' of an area to create a printable map that is gridded by the
lat/longs. I basically have an area of interest that I want to zoom in on,
split it into several parts and then have an axes for the lat/long on the
edges.
On Mon, Jan 18, 2010 at 8:31 AM, Markus Loecher <mar...@sensenetworks.com>wrote:
> sorry, I was not at a computer that could run R last night when I came up
> with the code, it needs some modification:
>
> shp=importShapefile(shpFile,projection="LL");
> bb <- qbbox(lat = shp[,"Y"], lon = shp[,"X"]);
> MyMap <- GetMap.bbox(bb$lonR, bb$latR, destfile = "DC.jpg");
> PlotPolysOnStaticMap(MyMap, shp, lwd=.5, col = rgb(0.25,0.25,0.25,0.025),
> add = F);
>
> and for an example that color codes the polygons individually
>
> #North Carolina SIDS data set:
> shpFile <- system.file("shapes/sids.shp", package="maptools");
> bb <- qbbox(lat = shp[,"Y"], lon = shp[,"X"]);
> MyMap <- GetMap.bbox(bb$lonR, bb$latR, destfile = "SIDS.jpg");
> #compute regularized SID rate
> sid <- 100*attr(shp, "PolyData")$SID74/(attr(shp, "PolyData")$BIR74+500)
> b <- as.integer(cut(sid, quantile(sid, seq(0,1,length=8)) ));
> b[is.na(b)] <- 1;
> opal <- col2rgb(grey.colors(7), alpha=TRUE)/255; opal["alpha",] <- 0.2;
> shp[,"col"] <- rgb(0.1,0.1,0.1,0.2);
> for (i in 1:length(b)) shp[shp[,"PID"] == i,"col"] <-
> rgb(opal[1,b[i]],opal[2,b[i]],opal[3,b[i]],opal[4,b[i]]);
> PlotPolysOnStaticMap(MyMap, shp, lwd=.5, col = shp[,"col"], add = F);
>
> Markus
>
>
> On Sun, Jan 17, 2010 at 9:13 PM, Markus Loecher
> <mar...@sensenetworks.com>wrote:
>
>> Good question, I should have added a proper example to the
>> PlotPolysOnStaticMap() function, which I wrote for that exact purpose.
>>
>> One way of overlaying, e.g. Census polygons on a Google static map would
>> be the following:
>>
>> require(PBSmapping);
>> shp=importShapefile('bg11_d00.shp');
>> bb <- qbbox(shp[,"X"], shp[,"Y"]);
>> MyMap <- GetMap.bbox(bb$lonR, bb$latR, destfile = "DC.png");
>> PlotPolysOnStaticMap(MyMap, shp, lwd=.25, col = 'lightgray', add = T);
>>
>> Here, I use the package PBSmapping to read the shapefile into a convenient
>> data frame format.
>> The shapefile bg11_d00.shp happens to be the census shapefile for
>> Washington DC (you'll also need the corresponding .dbf and .shx in the same
>> directory); I am planning to include a small shapefile in the library in the
>> future.
>> PlotPolysOnStaticMap() overlays the corresponding polygons on the map.
>>
>> Let me know if this works for you,
>>
>> Markus
>>
>>
>>
>>
>>
>> On Sat, Jan 16, 2010 at 8:35 PM, Patrick Crutcher <pcrutc...@gmail.com>wrote:
>>
>>> I have some shapefiles I want to plot over Google Maps tiles. I have
>>> polygons, lines and point data. What's the most efficient way to do this?
>>> One path might be to use the pkg RgoogleMaps, however, it is still unclear
>>> to me how to do this. I assume using PlotonStaticMap with some combination
>>> of reformatting the shapefile data. Thanks.
>>>
>>> P.
>>>
>>
>>
>
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