webtide {oce} | R Documentation |
Get a Tidal Prediction From a WebTide Database
Description
Get a tidal prediction from a WebTide database. This only works if the standalone WebTide application is installed, and if it is installed in a standard location. The details of installation are not within the oce purview.
Usage
webtide(
action = c("map", "predict"),
longitude,
latitude,
node,
time,
basedir = getOption("webtide"),
region = "nwatl",
plot = TRUE,
tformat,
debug = getOption("oceDebug"),
...
)
Arguments
action |
An indication of the action, either |
longitude , latitude |
optional location at which prediction is required (ignored if
|
node |
optional integer relating to a node in the database. If |
time |
a vector of times (in the UTC timezone)
at which prediction is to be made.
If not supplied, this will be the week starting at the present time,
computed with |
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 |
Details
There are two methods of using this function.
Case 1: action="map"
. In this case, if
plot
is FALSE
, a list is returned, containing
all the node
s in the selected database, along with all
the latitude
s and longitude
s. This value is
also returned (silently) if plot
is true, but in that case,
a plot is drawn to indicate the node locations. If latitude
and
longitude
are given, then the node nearest that spot is indicated on
the map; otherwise, if node
is given, then the location of that
node is indicated. There is also a special case: if node
is negative
and interactive()
is TRUE
,
then locator()
is called, and the node nearest the spot
where the user clicks the mouse is indicated in the plot and in the
return value.
Case 2: action="predict"
. If plot
is FALSE
,
then a list is returned, indicating time
, predicted
elevation
, velocity components u
and v
,
node
number, the name of the basedir
, and
the region
. If plot
is TRUE
, this list is returned
silently, and time-series plots are drawn for elevation, u, and v.
Naturally, webtide
will not work unless WebTide has been installed on
the computer.
Value
The value depends on action
:
If
action="map"
the return value is a list containing the index of the nearest node, along with thelatitude
andlongitude
of that node. Ifplot
isFALSE
, this value is returned invisibly.If
action="predict"
, the return value is a list containing a vector of times (time
), as well as vectors of the predictedelevation
in metres and the predicted horizontal components of velocity,u
andv
, along with thenode
number, and thebasedir
andregion
as supplied to this function. Ifplot
isFALSE
, this value is returned invisibly.
Caution
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.
Sample of Usage
# needs WebTide at the system level library(oce) # 1. prediction at Halifax NS longitude <- -63.57 latitude <- 44.65 prediction <- webtide("predict", longitude=longitude, latitude=latitude) mtext(paste0("prediction at ", latitude, "N and ", longitude, "E"), line=0.75, side=3) # 2. map webtide(lon=-63.57,lat=44.65,xlim=c(-64,-63),ylim=c(43.0,46))
Author(s)
Dan Kelley
Source
The WebTide software may be downloaded for free at the
Department of Fisheries and Oceans (Canada) website at
http://www.bio.gc.ca/science/research-recherche/ocean/webtide/index-en.php
(checked February 2016 and May 2017).
See Also
Other things related to tides:
[[,tidem-method
,
[[<-,tidem-method
,
as.tidem()
,
plot,tidem-method
,
predict.tidem()
,
summary,tidem-method
,
tidalCurrent
,
tidedata
,
tidem-class
,
tidemAstron()
,
tidemVuf()
,
tidem