Description Usage Arguments Details Value Webserver history Author(s) References See Also Examples
Data are downloaded (from https://maps.ngdc.noaa.gov/viewers/wcs-client, by
default) and a string containing the full path
to the downloaded file is returned. If destfile
is not supplied,
then the filename is constructed from the query, which means that
subsequent calls to dc.topo()
with identical parameters will
simply return the name of the cached file, assuming the user has not
deleted it in the meantime.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 |
west, east |
Longitudes of the western and eastern sides of the box. |
south, north |
Latitudes of the southern and northern sides of the box. |
resolution |
Optional grid spacing, in minutes. If not supplied,
a default value of 4 (corresponding to 7.4km, or 4 nautical
miles) is used. Note that (as of August 2016) the original data are on
a 1-minute grid, which limits the possibilities for |
format |
ignored, as of May 30, 2020. |
server |
character value giving the base name of the server, used in the construction of URL queries. Since servers tend to change over time, this is a good argument to check, when debugging code that once worked but now fails. |
destdir |
character value indicating the directory in which to store
downloaded files. The default value of |
destfile |
character value indicating the name of the file. If not supplied, then the file name is constructed from the other parameters of the function call, so that subsequent calls with the same parameters will yield the same result; this is useful for caching. |
force |
A logical value that indicates whether to force the download,
even if the pathname constructed from |
dryrun |
A logical value that indicates whether to return the constructed web query, without attempting to download the file. This can be helpful in designing responses to changing URLs. |
debug |
an integer specifying whether debugging information is
to be printed during processing. The printing is done by
a call to |
The data are downloaded with utils::download.file()
, using a URL
devised from reverse engineering web-based queries constructed by
the default server
used here. Note that the data source is
"etopo1"
, which is a 1 arc-second file (ref 1,2).
Three values are permitted for format
,
each named after the
targets of menu items on the
NOAA website (as of August 2016): (1) "aaigrid"
(for
the menu item "ArcGIS ASCII Grid"), which
yields a text file, (2) "netcdf"
(the default,
for the menu item named
"NetCDF"), which yields a NetCDF file
and (3) "gmt"
(for the menu item named
"GMT NetCDF"), which yields a NetCDF file in
another format. All of these file formats are
recognized by oce::read.topo()
in the oce package.
(The NOAA server has more options, and if
oce::read.topo()
is extended to handle them, they will
also be added here.)
String indicating the full pathname to the downloaded file.
This function has been changed repeatedly over the years, to keep up
with changes in server URLs and query strings. Until May 2020, the
NOAA server was set up to supply data in netcdf and other formats,
but then there was a change to only supply image (tiff) format
or JSON format, neither of which is particularly useful for reading
in R. To get around this, a scheme used by marmap::getNOAA.bathy()
was mimicked here, to convert a TIFF object into a raster object,
and then the result was written into a local netcdf file. In this way,
dc.topo()
is still able to accomplish what it has before May 2020,
although it stopped paying attention to the format
argument.
Dan Kelley
Dan Kelley 2020-05-30
https://www.ngdc.noaa.gov/mgg/global/global.html
Amante, C. and B.W. Eakins, 2009. ETOPO1 1 Arc-Minute Global Relief Model: Procedures, Data Sources and Analysis. NOAA Technical Memorandum NESDIS NGDC-24. National Geophysical Data Center, NOAA. doi:10.7289/V5C8276M (access date: Aug 30, 2017).
The work is done with utils::download.file()
.
Other functions that download ocean-related data:
dc.coastline()
,
dc.g1sst()
,
dc.hydrography()
,
dc.met()
,
dc.woa()
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | ## Not run:
library(dc)
topoFile <- dc.topo(west=-64, east=-60, south=43, north=46, destdir="~/data/topo")
library(oce)
topo <- read.topo(topoFile)
imagep(topo, zlim=c(-400, 400), drawTriangles=TRUE)
data(coastlineWorldFine, package="ocedata")
lines(coastlineWorldFine[["longitude"]], coastlineWorldFine[["latitude"]])
## End(Not run)
## Not run:
# not run because it is slow, and downloads files
library(dc)
library(oce)
f <- dc.topo(-70, -50, 35, 50, resolution=2, force=TRUE)
topo <- read.topo(f)
summary(topo)
imagep(topo, colormap(name="gmt_globe"))
## End(Not run)
|
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