webtide {oce} | R Documentation |
Get a tidal prediction from a WebTide database.
If action="map"
then a map is drawn, with a dot for the lower-left
corner of each triangle used in the finite-element tidal simulation upon
which WebTide predictions are based. If node
is missing, then
locator
is called, so that the user can indicate a spot of
interest on the map, and this point is indicated on the map (and in the
return value). If node
is provided, however, the point is indicated
but locator
is not called. (This second style is of use in
documenting interactive work after the fact.)
If action="predict"
then either a node number or the longitude and
latitude must be specified. If plot=TRUE
(the default) then a plot
is drawn, but no plot is produced otherwise. In either case, the (silent)
return value is a list as described in the next section. The times used for
prediction are specified with the time
argument, and if this is not
specified then a week following the present time is used.
Naturally, webtide
will not work unless WebTide has been installed on
the computer.
webtide(action = c("map", "predict"), longitude, latitude, node, time, basedir = getOption("webtide"), region = "nwatl", plot = TRUE, tformat, debug = getOption("oceDebug"), ...)
action |
An indication of the action, either |
longitude |
longitude at which prediction is required (ignored if
|
latitude |
latitude at which prediction is required (ignored if
|
node |
node to look up; only needed if |
time |
times at which prediction is to be made. If not supplied, this will be the week starting at the present time, incrementing by 15 minutes. |
basedir |
directory containing the |
region |
database region, given as a directory name in the WebTide
directory. For example, |
plot |
boolean indicating whether to plot. |
tformat |
optional argument passed to |
debug |
an integer specifying whether debugging information is
to be printed during the processing. This is a general parameter that
is used by many |
... |
optional arguments passed to plotting functions. A common
example is to set |
If action="map"
and plot=TRUE
, the return value is a
list containing the index of the nearest node, along with the
latitude
and longitude
of that node. If action="map"
and plot=FALSE
, the return value is a list of all nodes, longitude,
and latitudes.
If action="predict"
, the return value is a list containing a vector
of times (time
), as well as vectors of the predicted elevation
in metres and the predicted horizontal components of velocity, u
and
v
, along with the node
number, and the basedir
and
region
as supplied to this function.
WebTide is not an open-source application, so the present function was designed based on little more than guesses about the WebTide file structure. Users should be on the lookout for odd results.
Dan Kelley
The WebTide software may be downloaded for free at the
Department of Fisheries and Oceans (Canada) website, which in February 2016
was
http://www.bio.gc.ca/science/research-recherche/ocean/webtide/index-en.php
,
although this site seems not to be particularly static.
## Not run: library(oce) prediction <- webtide("predict", longitude=-69.61, latitude=48.14) ## End(Not run)