coord_proj | R Documentation |
'coord_proj' is a wrapper around ggplot2::coord_sf()
.
It simplifies specifying map limits ('xlim', 'ylim') in longitude and latitude (WGS84 CRS)
and automatically transforms them into the specified CRS for accurate projections.
This function extends the functionality of coord_sf()
to seamlessly handle user-specified
geographic boundaries in any projection, ensuring accurate mapping.
coord_proj(
crs = NULL,
xlim = NULL,
ylim = NULL,
expand = TRUE,
default_crs = "EPSG:4326",
...
)
crs |
A character string specifying the coordinate reference system (CRS) for the projection (e.g., '"EPSG:4326"' or custom projections like '"+proj=merc"'). |
xlim |
Longitude range (in degrees) to display, as a numeric vector of length 2. |
ylim |
Latitude range (in degrees) to display, as a numeric vector of length 2. |
expand |
Logical, whether to expand the plot limits. Default is 'TRUE'. |
default_crs |
A character string specifying the CRS of the input 'xlim' and 'ylim'. Default is '"EPSG:4326"'. |
... |
Additional arguments passed to |
A ggplot2 coord_sf
object with the transformed limits.
ggplot2::coord_sf
, geom_world
# World map with default projection and limits
ggplot() +
geom_world() +
coord_proj(
crs = "+proj=longlat +datum=WGS84",
xlim = c(-180, 180),
ylim = c(-90, 90),
expand=FALSE
) +
theme_minimal()
# Focused view with Azimuthal Equidistant projection
china_proj <- "+proj=aeqd +lat_0=35 +lon_0=105 +ellps=WGS84 +units=m +no_defs"
ggplot() +
geom_world(fill = "lightblue") +
coord_proj(
crs = china_proj,
xlim = c(60, 140),
ylim = c(-10, 50)
) +
theme_minimal()
# Display a small map of the South China Sea Islands with a custom projection
ggplot() +
geom_boundary_cn() +
theme_bw() +
coord_proj(
crs = china_proj,
expand = FALSE,
xlim = c(105, 123),
ylim = c(2, 23)
)
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