This function extracts the graph of an inla.mesh object and uses `geom_line`

to visualize
the graph's edges. Alternatively, if the `color`

argument is provided, interpolates the colors
across for a set of SpatialPixels covering the mesh area and calls `gg.SpatialPixelsDataFrame()`

to plot the interpolation.
Requires the `ggplot2`

package.

## Usage

```
# S3 method for inla.mesh
gg(
data,
color = NULL,
alpha = NULL,
edge.color = "grey",
edge.linewidth = 0.25,
interior = TRUE,
int.color = "blue",
int.linewidth = 0.5,
exterior = TRUE,
ext.color = "black",
ext.linewidth = 1,
crs = NULL,
mask = NULL,
nx = 500,
ny = 500,
...
)
```

## Arguments

- data
An

`inla.mesh`

object.- color
A vector of scalar values to fill the mesh with colors. The length of the vector mus correspond to the number of mesh vertices. The alternative name

`colour`

is also recognised.- alpha
A vector of scalar values setting the alpha value of the colors provided.

- edge.color
Color of the regular mesh edges.

- edge.linewidth
Line width for the regular mesh edges. Default 0.25

- interior
If TRUE, plot the interior boundaries of the mesh.

- int.color
Color used to plot the interior constraint edges.

- int.linewidth
Line width for the interior constraint edges. Default 0.5

- exterior
If TRUE, plot the exterior boundaries of the mesh.

- ext.color
Color used to plot the exterior boundary edges.

- ext.linewidth
Line width for the exterior boundary edges. Default 1

- crs
A CRS object supported by

`fm_transform()`

defining the coordinate system to project the mesh to before plotting.- mask
A SpatialPolygon defining the region that is plotted.

- nx
Number of pixels in x direction (when plotting using the color parameter).

- ny
Number of pixels in y direction (when plotting using the color parameter).

- ...
ignored arguments (S3 generic compatibility).

## Value

`geom_line`

return values or, if the color argument is used, the
values of `gg.SpatialPixelsDataFrame()`

.

## See also

Other geomes for meshes:
`gg.inla.mesh.1d()`

,
`gg()`

,
`gm()`

## Examples

```
# \donttest{
if (bru_safe_inla() &&
require(ggplot2, quietly = TRUE)) {
# Load Gorilla data
data("gorillas", package = "inlabru")
# Plot mesh using default edge colors
ggplot() +
gg(gorillas$mesh)
# Don't show interior and exterior boundaries
ggplot() +
gg(gorillas$mesh, interior = FALSE, exterior = FALSE)
# Change the edge colors
ggplot() +
gg(gorillas$mesh,
edge.color = "green",
int.color = "black",
ext.color = "blue"
)
# Use the x-coordinate of the vertices to colorize the triangles and
# mask the plotted area by the survey boundary, i.e. only plot the inside
xcoord <- gorillas$mesh$loc[, 1]
ggplot() +
gg(gorillas$mesh, color = (xcoord - 580), mask = gorillas$boundary) +
gg(gorillas$boundary)
}
# }
```