smoothLayer {cartography} R Documentation

## Smooth Layer

### Description

Plot a layer of smoothed data. It can also compute a ratio of potentials.

This function is a wrapper around the quickStewart function in SpatialPosition package.

The SpatialPosition package also provides:

• vignettes to explain the computation of potentials;

• more customizable inputs and outputs (custom distance matrix, raster output...);

• other functions related to spatial interactions (Reilly and Huff catchment areas).

### Usage

smoothLayer(
x,
spdf,
df,
spdfid = NULL,
dfid = NULL,
var,
var2 = NULL,
typefct = "exponential",
span,
beta,
resolution = NULL,
nclass = 8,
breaks = NULL,
col = NULL,
border = "grey20",
lwd = 1,
legend.pos = "bottomleft",
legend.title.txt = "Potential",
legend.title.cex = 0.8,
legend.values.cex = 0.6,
legend.values.rnd = 0,
legend.frame = FALSE,
)


### Arguments

 x an sf object, a simple feature collection. spdf a SpatialPolygonsDataFrame. df a data frame that contains the values to compute If df is missing spdf@data is used instead. spdfid name of the identifier variable in spdf, default to the first column of the spdf data frame. (optional) dfid name of the identifier variable in df, default to the first column of df. (optional) var name of the numeric variable used to compute potentials. var2 name of the numeric variable used to compute potentials. This variable is used for ratio computation (see Details). typefct character; spatial interaction function. Options are "pareto" (means power law) or "exponential". If "pareto" the interaction is defined as: (1 + alpha * mDistance) ^ (-beta). If "exponential" the interaction is defined as: exp(- alpha * mDistance ^ beta). The alpha parameter is computed from parameters given by the user (beta and span). span numeric; distance where the density of probability of the spatial interaction function equals 0.5. beta numeric; impedance factor for the spatial interaction function. resolution numeric; resolution of the output SpatialPointsDataFrame (in map units). mask sf object or SpatialPolygonsDataFrame; mask used to clip contours of potentials. nclass numeric; a targeted number of classes (default to 8). Not used if breaks is set. breaks numeric; a vector of values used to discretize the potentials. col a vector of colors. Note that if breaks is specified there must be one less colors specified than the number of break. border color of the polygons borders. lwd borders width. legend.pos position of the legend, one of "topleft", "top", "topright", "right", "bottomright", "bottom", "bottomleft", "left" or a vector of two coordinates in map units (c(x, y)). If legend.pos is "n" then the legend is not plotted. legend.title.txt title of the legend. legend.title.cex size of the legend title. legend.values.cex size of the values in the legend. legend.values.rnd number of decimal places of the values in the legend. legend.frame whether to add a frame to the legend (TRUE) or not (FALSE). add whether to add the layer to an existing plot (TRUE) or not (FALSE).

### Details

If var2 is provided the ratio between the potentials of var (numerator) and var2 (denominator) is computed.

### Value

An invisible sf object (MULTIPOLYGONs) is returned (see quickStewart).

### Examples

library(sf)