Usage
trajPlot(mydata, lon = "lon", lat = "lat", pollutant = "height", type = "default", map = TRUE, group = NA, map.fill = TRUE, map.res = "default", map.cols = "grey40", map.alpha = 0.4, projection = "lambert", parameters = c(51, 51), orientation = c(90, 0, 0), grid.col = "deepskyblue", npoints = 12, origin = TRUE, ...)
Arguments
mydata
Data frame, the result of importing a trajectory
file using importTraj.
lon
Column containing the longitude, as a decimal.
lat
Column containing the latitude, as a decimal.
pollutant
Pollutant to be plotted. By default the
trajectory height is used.
type
type determines how the data are split
i.e. conditioned, and then plotted. The default is will produce a
single plot using the entire data. Type can be one of the built-in
types as detailed in cutData e.g. "season", "year",
"weekday" and so on. For example, type = "season" will
produce four plots --- one for each season.It is also possible to choose type as another variable in
the data frame. If that variable is numeric, then the data will be
split into four quantiles (if possible) and labelled
accordingly. If type is an existing character or factor variable,
then those categories/levels will be used directly. This offers
great flexibility for understanding the variation of different
variables and how they depend on one another.
type can be up length two e.g. type = c("season",
"weekday") will produce a 2x2 plot split by season and day of
the week. Note, when two types are provided the first forms
the columns and the second the rows.
map
Should a base map be drawn? If TRUE the world
base map from the maps package is used.
group
It is sometimes useful to group and colour
trajectories according to a grouping variable. See example
below.
map.fill
Should the base map be a filled polygon? Default
is to fill countries.
map.res
The resolution of the base map. By default the
function uses the ‘world’ map from the maps
package. If map.res = "hires" then the (much) more
detailed base map ‘worldHires’ from the mapdata
package is used. Use library(mapdata). Also available
is a map showing the US states. In this case map.res =
"state" should be used.
map.cols
If map.fill = TRUE map.cols controls
the fill colour. Examples include map.fill = "grey40"
and map.fill = openColours("default", 10). The latter
colours the countries and can help differentiate them.
map.alpha
The transpency level of the filled map which
takes values from 0 (full transparency) to 1 (full
opacity). Setting it below 1 can help view trajectories,
trajectory surfaces etc. and a filled base map.
projection
The map projection to be used. Different map
projections are possible through the mapproj
package. See ?mapproject for extensive details and
information on setting other parameters and orientation (see
below).
parameters
From the mapproj package. Optional
numeric vector of parameters for use with the projection
argument. This argument is optional only in the sense that
certain projections do not require additional parameters. If a
projection does not require additional parameters then set to
null i.e. parameters = NULL.
orientation
From the mapproj package. An optional
vector c(latitude, longitude, rotation) which describes where
the "North Pole" should be when computing the
projection. Normally this is c(90, 0), which is appropriate
for cylindrical and conic projections. For a planar
projection, you should set it to the desired point of
tangency. The third value is a clockwise rotation (in
degrees), which defaults to the midrange of the longitude
coordinates in the map.
grid.col
The colour of the map grid to be used. To remove
the grid set grid.col = "transparent".
npoints
A dot is placed every npoints along each
full trajectory. For hourly back trajectories points are
plotted every npoint hours. This helps to understand
where the air masses were at particular times and get a feel
for the speed of the air (points closer togther correspond to
slower moving air masses).
origin
If true a filled circle dot is shown to mark the
receptor point.
...
other arguments are passed to cutData and
scatterPlot. This provides access to arguments used in
both these functions and functions that they in turn pass
arguments on to. For example, plotTraj passes the
argument cex on to scatterPlot which in turn
passes it on to the lattice function xyplot
where it is applied to set the plot symbol size.