- 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.border
The colour to use for the map outlines/borders. Defaults to
"black".
- 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.
- map.lwd
The map line width, a positive number, defaulting to 1.
- map.lty
The map line type. Line types can either be specified as an
integer (0 = blank, 1 = solid (default), 2 = dashed, 3 = dotted,
4 = dotdash, 5 = longdash, 6 = twodash) or as one of the character
strings "blank", "solid", "dashed", "dotted", "dotdash", "longdash", or
"twodash", where "blank" uses 'invisible lines' (i.e., does not draw them).
- 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.