The annulusMap()
function creates a map using polar annulus plots as
markers. Any number of pollutants can be specified using the pollutant
argument, and multiple layers of markers can be created using type
. By
default, these maps are dynamic and can be panned, zoomed, and otherwise
interacted with. Using the static
argument allows for static images to be
produced instead.
Usage
annulusMap(
data,
pollutant = NULL,
period = "hour",
limits = "free",
latitude = NULL,
longitude = NULL,
crs = 4326,
type = NULL,
popup = NULL,
label = NULL,
provider = "OpenStreetMap",
cols = "turbo",
alpha = 1,
key = FALSE,
legend = TRUE,
legend.position = NULL,
legend.title = NULL,
legend.title.autotext = TRUE,
control.collapsed = FALSE,
control.position = "topright",
control.autotext = TRUE,
d.icon = 200,
d.fig = 3.5,
static = FALSE,
static.nrow = NULL,
progress = TRUE,
n.core = 1L,
...,
control = NULL
)
Arguments
- data
Input data table with pollutant, wind, and geo-spatial information.
required | scope: dynamic & static
A data frame. The data frame must contain the data to plot the directional analysis marker, which includes wind speed (
ws
), wind direction (wd
), and the column representing the concentration of a pollutant. In addition,data
must include a decimal latitude and longitude (or X/Y coordinate used in conjunction withcrs
).- pollutant
Pollutant name(s).
required | scope: dynamic & static
The column name(s) of the pollutant(s) to plot. If multiple pollutants are specified and a non-pairwise statistic is supplied, the
type
argument will no longer be able to be used and:Dynamic: The pollutants can be toggled between using a "layer control" menu.
Static:: The pollutants will each appear in a different panel.
Multiple
pollutants
prohibit the use of thetype
argument for non-pairwise statistics.- period
Temporal period for radial axis.
default:
"hour"
| scope: dynamic & staticOptions are "hour" (the default, to plot diurnal variations), "season" to plot variation throughout the year, "weekday" to plot day of the week variation and "trend" to plot the trend by wind direction.
- limits
Specifier for the plot colour scale bounds.
default:
"free"
| scope: dynamic & staticOne of:
"fixed"
which ensures all of the markers use the same colour scale."free"
(the default) which allows all of the markers to use different colour scales.A numeric vector in the form
c(lower, upper)
used to define the colour scale. For example,limits = c(0, 100)
would force the plot limits to span 0-100.
- latitude, longitude
The decimal latitude(Y)/longitude(X).
default:
NULL
| scope: dynamic & staticColumn names representing the decimal latitude and longitude (or other Y/X coordinate if using a different
crs
). If not provided, will be automatically inferred from data by looking for a column named "lat"/"latitude" or "lon"/"lng"/"long"/"longitude" (case-insensitively).- crs
The coordinate reference system (CRS).
default:
4326
| scope: dynamic & staticThe coordinate reference system (CRS) of the data, passed to
sf::st_crs()
. By default this is EPSG:4326, the CRS associated with the commonly used latitude and longitude coordinates. Different coordinate systems can be specified usingcrs
(e.g.,crs = 27700
for the British National Grid). Note that non-lat/lng coordinate systems will be re-projected to EPSG:4326 for plotting on the map.- type
A method to condition the
data
for separate plotting.default:
NULL
| scope: dynamic & staticUsed for splitting the input data into different groups, passed to the
type
argument ofopenair::cutData()
. Whentype
is specified:Dynamic: The different data splits can be toggled between using a "layer control" menu.
Static:: The data splits will each appear in a different panel.
type
cannot be used if multiplepollutant
columns have been provided.- popup
Content for marker popups on dynamic maps.
default:
NULL
| scope: dynamicColumns to be used as the HTML content for marker popups on dynamic maps. Popups may be useful to show information about the individual sites (e.g., site names, codes, types, etc.). If a vector of column names are provided they are passed to
buildPopup()
using its default values.- label
Content for marker hover-over on dynamic maps.
default:
NULL
| scope: dynamicColumn to be used as the HTML content for hover-over labels. Labels are useful for the same reasons as popups, though are typically shorter.
- provider
The basemap(s) to be used.
default:
"OpenStreetMap"
| scope: dynamic & staticThe base map(s) to be used beneath the polar markers. If not provided, will default to
"OpenStreetMap"
/"osm"
for both dynamic and static maps.Dynamic: Any number of leaflet::providers. See http://leaflet-extras.github.io/leaflet-providers/preview/ for a list of all base maps that can be used. If multiple base maps are provided, they can be toggled between using a "layer control" interface. By default, the interface will use the provider names as labels, but users can define their own using a named vector (e.g.,
c("Default" = "OpenStreetMap", "Satellite" = "Esri.WorldImagery")
)Static: One of
rosm::osm.types()
.
There is some overlap in static and dynamic providers. For example,
{ggspatial}
uses "osm" to specify "OpenStreetMap". When static providers are provided to dynamic maps or vice versa,{openairmaps}
will attempt to substitute the correct provider string.- cols
Colours to use for plotting.
default:
"turbo"
| scope: dynamic & staticThe colours used for plotting, passed to
openair::openColours()
. The default,"turbo"
, is a rainbow palette with relatively perceptually uniform colours.- alpha
Transparency value for polar markers.
default:
1
| scope: dynamic & staticA value between 0 (fully transparent) and 1 (fully opaque).
- key
Draw individual marker legends?
default:
FALSE
| scope: dynamic & staticDraw a key for each individual marker? Potentially useful when
limits = "free"
, but of limited use otherwise.- legend
Draw a shared legend?
default:
TRUE
| scope: dynamic & staticWhen all markers share the same colour scale (e.g., when
limits != "free"
inpolarMap()
), should a shared legend be created at the side of the map?- legend.position
Position of the shared legend.
default:
NULL
| scope: dynamic & staticWhen
legend = TRUE
, where should the legend be placed?Dynamic: One of "topright", "topright", "bottomleft" or "bottomright". Passed to the
position
argument ofleaflet::addLegend()
.Static:: One of "top", "right", "bottom" or "left". Passed to the
legend.position
argument ofggplot2::theme()
.
- legend.title
Title of the legend.
default:
NULL
| scope: dynamic & staticBy default, when
legend.title = NULL
, the function will attempt to provide a sensible legend title.legend.title
allows users to overwrite this - for example, to include units or other contextual information. For dynamic maps, users may wish to use HTML tags to format the title.- legend.title.autotext
Automatically format the title of the legend?
default:
TRUE
| scope: dynamic & staticWhen
legend.title.autotext = TRUE
,legend.title
will be first run throughquickTextHTML()
(dynamic) oropenair::quickText()
(static).- control.collapsed
Show the layer control as a collapsed?
default:
FALSE
| scope: dynamicFor dynamic maps, should the "layer control" interface be collapsed? If
TRUE
, users will have to hover over an icon to view the options.- control.position
Position of the layer control menu
default:
"topright"
| scope: dynamicWhen
type != NULL
, or multiple pollutants are specified, where should the "layer control" interface be placed? One of "topleft", "topright", "bottomleft" or "bottomright". Passed to theposition
argument ofleaflet::addLayersControl()
.- control.autotext
Automatically format the content of the layer control menu?
default:
TRUE
| scope: dynamicWhen
control.autotext = TRUE
, the content of the "layer control" interface will be first run throughquickTextHTML()
.- d.icon
The diameter of the plot on the map in pixels.
default:
200
| scope: dynamic & staticThis will affect the size of the individual polar markers. Alternatively, a vector in the form
c(width, height)
can be provided if a non-circular marker is desired.- d.fig
The diameter of the plots to be produced using
{openair}
in inches.default:
3.5
| scope: dynamic & staticThis will affect the resolution of the markers on the map. Alternatively, a vector in the form
c(width, height)
can be provided if a non-circular marker is desired.- static
Produce a static map?
default:
FALSE
This controls whether a dynamic or static map is produced. The former is the default and is broadly more useful, but the latter may be preferable for DOCX or PDF outputs (e.g., academic papers).
- static.nrow
Number of rows in a static map.
default:
NULL
| scope: staticControls the number of rows of panels on a static map when multiple
pollutant
s ortype
are specified; passed to thenrow
argument ofggplot2::facet_wrap()
. The default,NULL
, results in a roughly square grid of panels.- progress
Show a progress bar?
default:
TRUE
| scope: dynamic & staticBy default, a progress bar is shown to visualise the function's progress creating individual polar markers. This option allows this to be turned off, if desired.
- n.core
Number of cores to use in parallel processing.
default:
1L
| scope: dynamic & staticBy default, each polar marker is drawn and saved sequentially. For big maps with a lot of markers, this can be slow. Adjusting
n.core
to a number greater than1
will use mirai to create markers in parallel.- ...
Arguments passed on to
openair::polarAnnulus
resolution
Two plot resolutions can be set: “normal” and “fine” (the default).
local.tz
Should the results be calculated in local time that includes a treatment of daylight savings time (DST)? The default is not to consider DST issues, provided the data were imported without a DST offset. Emissions activity tends to occur at local time e.g. rush hour is at 8 am every day. When the clocks go forward in spring, the emissions are effectively released into the atmosphere typically 1 hour earlier during the summertime i.e. when DST applies. When plotting diurnal profiles, this has the effect of “smearing-out” the concentrations. Sometimes, a useful approach is to express time as local time. This correction tends to produce better-defined diurnal profiles of concentration (or other variables) and allows a better comparison to be made with emissions/activity data. If set to
FALSE
then GMT is used. Examples of usage includelocal.tz = "Europe/London"
,local.tz = "America/New_York"
. SeecutData
andimport
for more details.statistic
The statistic that should be applied to each wind speed/direction bin. Can be “mean” (default), “median”, “max” (maximum), “frequency”. “stdev” (standard deviation), “weighted.mean” or “cpf” (Conditional Probability Function). Because of the smoothing involved, the colour scale for some of these statistics is only to provide an indication of overall pattern and should not be interpreted in concentration units e.g. for
statistic = "weighted.mean"
where the bin mean is multiplied by the bin frequency and divided by the total frequency. In many cases usingpolarFreq
will be better. Settingstatistic = "weighted.mean"
can be useful because it provides an indication of the concentration * frequency of occurrence and will highlight the wind speed/direction conditions that dominate the overall mean.percentile
If
statistic = "percentile"
orstatistic = "cpf"
thenpercentile
is used, expressed from 0 to 100. Note that the percentile value is calculated in the wind speed, wind direction ‘bins’. For this reason it can also be useful to setmin.bin
to ensure there are a sufficient number of points available to estimate a percentile. Seequantile
for more details of how percentiles are calculated.width
The width of the annulus; can be “normal” (the default), “thin” or “fat”.
min.bin
The minimum number of points allowed in a wind speed/wind direction bin. The default is 1. A value of two requires at least 2 valid records in each bin an so on; bins with less than 2 valid records are set to NA. Care should be taken when using a value > 1 because of the risk of removing real data points. It is recommended to consider your data with care. Also, the
polarFreq
function can be of use in such circumstances.exclude.missing
Setting this option to
TRUE
(the default) removes points from the plot that are too far from the original data. The smoothing routines will produce predictions at points where no data exist i.e. they predict. By removing the points too far from the original data produces a plot where it is clear where the original data lie. If set toFALSE
missing data will be interpolated.date.pad
For
type = "trend"
(default),date.pad = TRUE
will pad-out missing data to the beginning of the first year and the end of the last year. The purpose is to ensure that the trend plot begins and ends at the beginning or end of year.force.positive
The default is
TRUE
. Sometimes if smoothing data with steep gradients it is possible for predicted values to be negative.force.positive = TRUE
ensures that predictions remain positive. This is useful for several reasons. First, with lots of missing data more interpolation is needed and this can result in artefacts because the predictions are too far from the original data. Second, if it is known beforehand that the data are all positive, then this option carries that assumption through to the prediction. The only likely time where settingforce.positive = FALSE
would be if background concentrations were first subtracted resulting in data that is legitimately negative. For the vast majority of situations it is expected that the user will not need to alter the default option.k
The smoothing value supplied to
gam
for the temporal and wind direction components, respectively. In some cases e.g. a trend plot with less than 1-year of data the smoothing with the default values may become too noisy and affected more by outliers. Choosing a lower value ofk
(say 10) may help produce a better plot.normalise
If
TRUE
concentrations are normalised by dividing by their mean value. This is done after fitting the smooth surface. This option is particularly useful if one is interested in the patterns of concentrations for several pollutants on different scales e.g. NOx and CO. Often useful if more than onepollutant
is chosen.key.header
Adds additional text/labels to the scale key. For example, passing the options
key.header = "header", key.footer = "footer1"
adds addition text above and below the scale key. These arguments are passed todrawOpenKey
viaquickText
, applying theauto.text
argument, to handle formatting.key.footer
see
key.footer
.key.position
Location where the scale key is to plotted. Allowed arguments currently include
"top"
,"right"
,"bottom"
and"left"
.auto.text
Either
TRUE
(default) orFALSE
. IfTRUE
titles and axis labels will automatically try and format pollutant names and units properly e.g. by subscripting the `2' in NO2.
- control
Deprecated. Please use
type
.
Value
Either:
Dynamic: A leaflet object
Static: A
ggplot2
object usingggplot2::coord_sf()
coordinates with aggspatial
basemap
Customisation of static maps using ggplot2
As the outputs of the static directional analysis functions are ggplot2
figures, further customisation is possible using functions such as
ggplot2::theme()
, ggplot2::guides()
and ggplot2::labs()
.
If multiple pollutants are specified, subscripting (e.g., the "x" in "NOx")
is achieved using the ggtext package. Therefore if you
choose to override the plot theme, it is recommended to use
[ggplot2::theme()]
and [ggtext::element_markdown()]
to define the
strip.text
parameter.
When arguments like limits
, percentile
or breaks
are defined, a
legend is automatically added to the figure. Legends can be removed using
ggplot2::theme(legend.position = "none")
, or further customised using
ggplot2::guides()
and either color = ggplot2::guide_colourbar()
for
continuous legends or fill = ggplot2::guide_legend()
for discrete
legends.
See also
Other directional analysis maps:
diffMap()
,
freqMap()
,
percentileMap()
,
polarMap()
,
pollroseMap()
,
windroseMap()