(This article was first published on

**Omnia sunt Communia! » R-english**, and kindly contributed to R-bloggers)The function `slopeAspect`

from `raster`

provides the vector field (gradient) from a scalar field stored in a `RasterLayer`

object. The magnitude (slope) and direction (aspect) of the vector field is usually displayed with a set of arrows (e.g. `quiver`

in Matlab). `rasterVis`

includes now a method, `vectorplot`

, to calculate and display this vector field

df <- expand.grid(x=seq(-2, 2, .1), y=seq(-2, 2, .1)) df$z <- with(df, (3*x^2 + y)*exp(-x^2-y^2)) r <- rasterFromXYZ(df) projection(r) <- CRS("+proj=longlat +datum=WGS84")vectorplot(r, par.settings=RdBuTheme)

To

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