- 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 transparency 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
together correspond to slower moving air masses). If npoints = NA
then no points are added.
- origin
If true a filled circle dot is shown to mark the receptor
point.
- plot
Should a plot be produced? FALSE can be useful when analysing
data to extract plot components and plotting them in other ways.
- ...
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.