This set of geom, stat, and coord are used to visualise simple feature (sf)
objects. For simple plots, you will only need geom_sf() as it
uses stat_sf() and adds coord_sf() for you. geom_sf() is
an unusual geom because it will draw different geometric objects depending
on what simple features are present in the data: you can get points, lines,
or polygons.
For text and labels, you can use geom_sf_text() and geom_sf_label().
stat_sf(mapping = NULL, data = NULL, geom = "rect",
position = "identity", na.rm = FALSE, show.legend = NA,
inherit.aes = TRUE, ...)geom_sf(mapping = aes(), data = NULL, stat = "sf",
position = "identity", na.rm = FALSE, show.legend = NA,
inherit.aes = TRUE, ...)
geom_sf_label(mapping = aes(), data = NULL, stat = "sf_coordinates",
position = "identity", ..., parse = FALSE, nudge_x = 0,
nudge_y = 0, label.padding = unit(0.25, "lines"),
label.r = unit(0.15, "lines"), label.size = 0.25, na.rm = FALSE,
show.legend = NA, inherit.aes = TRUE, fun.geometry = NULL)
geom_sf_text(mapping = aes(), data = NULL, stat = "sf_coordinates",
position = "identity", ..., parse = FALSE, nudge_x = 0,
nudge_y = 0, check_overlap = FALSE, na.rm = FALSE,
show.legend = NA, inherit.aes = TRUE, fun.geometry = NULL)
coord_sf(xlim = NULL, ylim = NULL, expand = TRUE, crs = NULL,
datum = sf::st_crs(4326), label_graticule = waiver(),
label_axes = waiver(), ndiscr = 100, default = FALSE,
clip = "on")
The data to be displayed in this layer. There are three options:
If NULL, the default, the data is inherited from the plot
data as specified in the call to ggplot().
A data.frame, or other object, will override the plot
data. All objects will be fortified to produce a data frame. See
fortify() for which variables will be created.
A function will be called with a single argument,
the plot data. The return value must be a data.frame, and
will be used as the layer data.
The geometric object to use display the data
Position adjustment, either as a string, or the result of a call to a position adjustment function.
If FALSE, the default, missing values are removed with
a warning. If TRUE, missing values are silently removed.
logical. Should this layer be included in the legends?
NA, the default, includes if any aesthetics are mapped.
FALSE never includes, and TRUE always includes.
You can also set this to one of "polygon", "line", and "point" to override the default legend.
If FALSE, overrides the default aesthetics,
rather than combining with them. This is most useful for helper functions
that define both data and aesthetics and shouldn't inherit behaviour from
the default plot specification, e.g. borders().
Other arguments passed on to layer(). These are
often aesthetics, used to set an aesthetic to a fixed value, like
colour = "red" or size = 3. They may also be parameters
to the paired geom/stat.
The statistical transformation to use on the data for this layer, as a string.
If TRUE, the labels will be parsed into expressions and
displayed as described in ?plotmath.
Horizontal and vertical adjustment to nudge labels by. Useful for offsetting text from points, particularly on discrete scales.
Horizontal and vertical adjustment to nudge labels by. Useful for offsetting text from points, particularly on discrete scales.
Amount of padding around label. Defaults to 0.25 lines.
Radius of rounded corners. Defaults to 0.15 lines.
Size of label border, in mm.
A function that takes a sfc object and returns a sfc_POINT with the
same length as the input. If NULL, function(x) sf::st_point_on_surface(sf::st_zm(x))
will be used. Note that the function may warn about the incorrectness of
the result if the data is not projected, but you can ignore this except
when you really care about the exact locations.
If TRUE, text that overlaps previous text in the
same layer will not be plotted.
Limits for the x and y axes.
Limits for the x and y axes.
If TRUE, the default, adds a small expansion factor to
the limits to ensure that data and axes don't overlap. If FALSE,
limits are taken exactly from the data or xlim/ylim.
Use this to select a specific coordinate reference system (CRS). If not specified, will use the CRS defined in the first layer.
CRS that provides datum to use when generating graticules
Character vector indicating which graticule lines should be labeled
where. Meridians run north-south, and the letters "N" and "S" indicate that
they should be labeled on their north or south end points, respectively.
Parallels run east-west, and the letters "E" and "W" indicate that they
should be labeled on their east or west end points, respectively. Thus,
label_graticule = "SW" would label meridians at their south end and parallels at
their west end, whereas label_graticule = "EW" would label parallels at both
ends and meridians not at all. Because meridians and parallels can in general
intersect with any side of the plot panel, for any choice of label_graticule labels
are not guaranteed to reside on only one particular side of the plot panel.
This parameter can be used alone or in combination with label_axes.
Character vector or named list of character values
specifying which graticule lines (meridians or parallels) should be labeled on
which side of the plot. Meridians are indicated by "E" (for East) and
parallels by "N" (for North). Default is "--EN", which specifies
(clockwise from the top) no labels on the top, none on the right, meridians
on the bottom, and parallels on the left. Alternatively, this setting could have been
specified with list(bottom = "E", left = "N").
This parameter can be used alone or in combination with label_graticule.
number of segments to use for discretising graticule lines; try increasing this when graticules look unexpected
Is this the default coordinate system? If FALSE (the default),
then replacing this coordinate system with another one creates a message alerting
the user that the coordinate system is being replaced. If TRUE, that warning
is suppressed.
Should drawing be clipped to the extent of the plot panel? A
setting of "on" (the default) means yes, and a setting of "off"
means no. In most cases, the default of "on" should not be changed,
as setting clip = "off" can cause unexpected results. It allows
drawing of data points anywhere on the plot, including in the plot margins. If
limits are set via xlim and ylim and some data points fall outside those
limits, then those data points may show up in places such as the axes, the
legend, the plot title, or the plot margins.
geom_sf() uses a unique aesthetic: geometry, giving an
column of class sfc containing simple features data. There
are three ways to supply the geometry aesthetic:
Do nothing: by default geom_sf() assumes it is stored in
the geometry column.
Explicitly pass an sf object to the data argument.
This will use the primary geometry column, no matter what it's called.
Supply your own using aes(geometry = my_column)
Unlike other aesthetics, geometry will never be inherited from
the plot.
coord_sf() ensures that all layers use a common CRS. You can
either specify it using the CRS param, or coord_sf() will
take it from the first layer that defines a CRS.
# NOT RUN {
if (requireNamespace("sf", quietly = TRUE)) {
nc <- sf::st_read(system.file("shape/nc.shp", package = "sf"), quiet = TRUE)
ggplot(nc) +
geom_sf(aes(fill = AREA))
# If not supplied, coord_sf() will take the CRS from the first layer
# and automatically transform all other layers to use that CRS. This
# ensures that all data will correctly line up
nc_3857 <- sf::st_transform(nc, "+init=epsg:3857")
ggplot() +
geom_sf(data = nc) +
geom_sf(data = nc_3857, colour = "red", fill = NA)
# Unfortunately if you plot other types of feature you'll need to use
# show.legend to tell ggplot2 what type of legend to use
nc_3857$mid <- sf::st_centroid(nc_3857$geometry)
ggplot(nc_3857) +
geom_sf(colour = "white") +
geom_sf(aes(geometry = mid, size = AREA), show.legend = "point")
# You can also use layers with x and y aesthetics: these are
# assumed to already be in the common CRS.
ggplot(nc) +
geom_sf() +
annotate("point", x = -80, y = 35, colour = "red", size = 4)
# Thanks to the power of sf, a geom_sf nicely handles varying projections
# setting the aspect ratio correctly.
library(maps)
world1 <- sf::st_as_sf(map('world', plot = FALSE, fill = TRUE))
ggplot() + geom_sf(data = world1)
world2 <- sf::st_transform(
world1,
"+proj=laea +y_0=0 +lon_0=155 +lat_0=-90 +ellps=WGS84 +no_defs"
)
ggplot() + geom_sf(data = world2)
# To add labels, use geom_sf_label().
ggplot(nc_3857[1:3, ]) +
geom_sf(aes(fill = AREA)) +
geom_sf_label(aes(label = NAME))
}
# }
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