importTraj
function.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, ...)importTraj.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.
TRUE the world
base map from the maps package is used.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.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.mapproj
package. See ?mapproject for extensive details and
information on setting other parameters and orientation (see
below).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.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 = "transparent".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).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.trajPlot by
default will plot each lat/lon location showing the origin of
each trajectory, if no pollutant is supplied. If a pollutant is given, by merging the trajectory data with
concentration data (see example below), the trajectories are
colour-coded by the concentration of pollutant. With a long
time series there can be lots of overplotting making it difficult
to gauge the overall concentration pattern. In these cases setting
alpha to a low value e.g. 0.1 can help. The user can aslo show points instead of lines by plot.type
= "p". Note that trajPlot will plot only the full length
trajectories. This should be remembered when selecting only part
of a year to plot.importTraj to import trajectory data from
the King's College server and trajLevel for
trajectory binning functions.
# show a simple case with no pollutant i.e. just the trajectories
# let's check to see where the trajectories were coming from when
# Heathrow Airport was closed due to the Icelandic volcanic eruption
# 15--21 April 2010.
# import trajectories for London and plot
## Not run: ------------------------------------
# lond <- importTraj("london", 2010)
# # well, HYSPLIT seems to think there certainly were conditions where trajectories
# # orginated from Iceland...
# trajPlot(selectByDate(lond, start = "15/4/2010", end = "21/4/2010"))
## ---------------------------------------------
# plot by day, need a column that makes a date
## Not run: ------------------------------------
# lond$day <- as.Date(lond$date)
# trajPlot(selectByDate(lond, start = "15/4/2010", end = "21/4/2010"),
# type = "day")
## ---------------------------------------------
# or show each day grouped by colour, with some other options set
## Not run: ------------------------------------
# trajPlot(selectByDate(lond, start = "15/4/2010", end = "21/4/2010"),
# group = "day", col = "jet", lwd = 2, key.pos = "right", key.col = 1)
## ---------------------------------------------
# more examples to follow linking with concentration measurements...
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