These functions visualise geofield
data as contours in 2D. They are built
on top of geom_contour
and
geom_contour_filled
.
They require data frames with a column containing
geofield
s. This would normally be a
geolist
column, but a standard list column containing
geofields will also work.
Smoothing can be achieved by upscaling the data before plotting. This can only be done using an integer scale factor and the methods can be any function that summarises a vector into a single value, for example "mean", "median", "min", "max", or "downsample". Downsampling is simply sampling a pixel within the upscaled pixel - by default this is the centre.
Usage
geom_geocontour(
mapping = NULL,
data = NULL,
position = "identity",
...,
bins = NULL,
binwidth = NULL,
breaks = NULL,
lineend = "butt",
linejoin = "round",
linemitre = 10,
upscale_factor = 1,
upscale_method = "mean",
downsample_location = "centre",
na.rm = FALSE,
show.legend = NA,
inherit.aes = TRUE
)
geom_geocontour_filled(
mapping = NULL,
data = NULL,
position = "identity",
...,
bins = NULL,
binwidth = NULL,
breaks = NULL,
upscale_factor = 1,
upscale_method = "mean",
downsample_location = "centre",
na.rm = FALSE,
show.legend = NA,
inherit.aes = TRUE
)
Arguments
- mapping
Set of aesthetic mappings created by
aes()
. If specified andinherit.aes = TRUE
(the default), it is combined with the default mapping at the top level of the plot. You must supplymapping
if there is no plot mapping.- data
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 toggplot()
.A
data.frame
, or other object, will override the plot data. All objects will be fortified to produce a data frame. Seefortify()
for which variables will be created.A
function
will be called with a single argument, the plot data. The return value must be adata.frame
, and will be used as the layer data. Afunction
can be created from aformula
(e.g.~ head(.x, 10)
).- position
Position adjustment, either as a string naming the adjustment (e.g.
"jitter"
to useposition_jitter
), or the result of a call to a position adjustment function. Use the latter if you need to change the settings of the adjustment.- ...
Other arguments passed on to
layer()
. These are often aesthetics, used to set an aesthetic to a fixed value, likecolour = "red"
orsize = 3
. They may also be parameters to the paired geom/stat.- bins
Number of contour bins. Overridden by
breaks
.- binwidth
The width of the contour bins. Overridden by
bins
.- breaks
One of:
Numeric vector to set the contour breaks
A function that takes the range of the data and binwidth as input and returns breaks as output. A function can be created from a formula (e.g. ~ fullseq(.x, .y)).
Overrides
binwidth
andbins
. By default, this is a vector of length ten withpretty()
breaks.- lineend
Line end style (round, butt, square).
- linejoin
Line join style (round, mitre, bevel).
- linemitre
Line mitre limit (number greater than 1).
- upscale_factor
An integer by which to upscale the data before computing the contours. For example if this is 2, the upscaled grid will have 2 pixels in each direction from the grid before upscaling.
- upscale_method
The method used for upscaling. See
geo_upscale
for more details.- downsample_location
When "downsample" is the chosen method, each pixel in the upscaled field is sampled from a pixel from the original field that is inside the upscaled pixel. The location of that pixel can be one of "bottom_left", "bottom_centre", "bottom_right", "left_centre", "centre", "right_centre", "top_right", "top_centre", "top_left" or "random".
- na.rm
If
FALSE
, the default, missing values are removed with a warning. IfTRUE
, missing values are silently removed.- show.legend
logical. Should this layer be included in the legends?
NA
, the default, includes if any aesthetics are mapped.FALSE
never includes, andTRUE
always includes. It can also be a named logical vector to finely select the aesthetics to display.- inherit.aes
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()
.
Aesthetics
geom_geocontour()
understands the following aesthetics
(required aesthetics are in bold):
geofield
colour
alpha
group
linetype
linewidth
weight
geom_geocontour_filled()
understands the following aesthetics (required
aesthetics are in bold):
geofield
colour
fill
alpha
group
linetype
linewidth
weight
Computed variables
These are calculated by the 'stat' part of layers and can be accessed with delayed evaluation. The computed variables differ somewhat for contour lines (compbuted by stat_contour()
) and contour bands (filled contours, computed by stat_contour_filled()
). The variables nlevel
and piece
are available for both, whereas level_low
, level_high
, and level_mid
are only available for bands. The variable level
is a numeric or a factor depending on whether lines or bands are calculated.
after_stat(level)
Height of contour. For contour lines, this is a numeric vector that represents bin boundaries. For contour bands, this is an ordered factor that represents bin ranges.after_stat(level_low)
,after_stat(level_high)
,after_stat(level_mid)
(contour bands only) Lower and upper bin boundaries for each band, as well as the mid point between boundaries.after_stat(nlevel)
Height of contour, scaled to a maximum of 1.after_stat(piece)
Contour piece (an integer).