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copied!<p>Since you are using geographical data, maybe the <code>raster</code> package is useful for you. For example, let's display the altitude of France (download this <a href="http://diva-gis.org/data/alt/FRA_alt.zip" rel="nofollow"><code>zip</code></a> file or use the <code>raster::getData</code> function). After you <code>unzip</code> the file:</p> <pre><code>library(raster) fraAlt <- raster('FRA_alt') plot(fraAlt) ## Not only France is displayed... </code></pre> <p>If you want to display only the altitude of France, you need the information of the boundaries: download this <a href="http://gadm.org/data/rda/FRA_adm0.RData" rel="nofollow"><code>RData</code></a> file (or use the <code>raster::getData</code> function). This <code>RData</code> contains a <code>SpatialPolygonsDataFrame</code> (named <code>gadm</code>) which can be converted to a <code>Raster</code> with:</p> <pre><code> mk <- rasterize(gadm, fraAlt) </code></pre> <p>Now you can mask the altitude raster with the boundaries:</p> <pre><code> fraAltMask <- mask(fraAlt, x) plot(fraAltMask) ##Now only France is displayed </code></pre> <p>Finally, if you want to use <code>lattice</code> methods you need the <code>rasterVis</code> package:</p> <pre><code> library(rasterVis) levelplot(fraAlt) levelplot(fraAltMask) </code></pre> <p>Now, all together with the boundaries superimposed:</p> <pre><code> s <- stack(fraAlt, fraAltMask) layerNames(s) <- c('Alt', 'AltMask') boundaries <- as(gadm, 'SpatialLines') levelplot(s) + layer(sp.lines(boundaries)) </code></pre>

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