dc.argo: Download and Cache an Argo Dataset
In dankelley/dac: Download and Cache Data

Description Usage Arguments Details Value Caution Author(s) References See Also Examples

Download and cache data from an argo profiling float.

dc.argo(
  id,
  longitude,
  latitude,
  time,
  server = "ftp://usgodae.org",
  destdir = ".",
  destfile,
  force = FALSE,
  dryrun = FALSE,
  debug = getOption("dcDebug", 0)
)

`id`	a character string giving the float ID to be queried. argo float. If this is provided, then `longitude`, `latitude` and `time` are ignored, and `dc.argo()` downloads a file that contains all the profiles for the named float. FIXME/dk: I think this text is garbled and out of date.
`longitude`	Two-element numerical vector holding the limits of longitude (degrees East) to search for Argo profiles.
`latitude`	Two-element numerical vector holding the latitude limits (degrees North).
`time`	Two-element character vector holding the time limits in YYYY-MM-DD format.
`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 `"."` means to store the downloaded file in the present working directory. Set `destdir=NULL` if `destfile` is a filename with full path information. File clutter is reduced by creating a top-level directory called `data`, with subdirectories for various file types; see “Examples”.
`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 `destdir` and `destfile` already exists.
`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 `dcDebug()`. Setting `debug=0` turns off this form of debugging, while higher values yield more information. If one `dc` function calls another, it passes the value of `debug` but decreased by 1, which means that the value of `debug` controls not just the breadth of debugging, but also the depth.

dc.argoById() downloads data for the float with a specified identifier, dc.argoSearch() downloads the most recent profile for all floats in a specified longitude, latitude, and time box, and dc.argo is a wrapper that calls either of the first two functions, depending on whether the id argument is provided.

In any case, the downloads are made from the USGODAE server (ref 1) by default (or from any other server that obeys the same directory structure). Since the servers do not provide an API for such downloads, the dc.argo* functions are forced to work by constructing URLs that are devised based on inspection of queries constructed from a GUI-style webpage (ref 2). This leads to a brittleness that is discussed in “Caution”.

String indicating the full pathname to the downloaded file.

The queries used by the dc.argo functions will fail if USGODAE changes their system. For an example, USGODAE presently looks for the substring ".submit=++Go++" in the query, but if this were to be switched to ".submit=Go", a seemingly trivial change, then dc.argo would fail entirely. For this reason, the read.argo* functions may fail at any time. Users who encounter this problem should contact the author, who may be able to find a way to reverse-engineer the updated Argo system.

Dan Kelley

Other functions related to argo data: dc.argoById(), dc.argoIndex(), dc.argoSearch()

library(dc)
## Not run: 
library(oce)
## 1. Get float profiles near Nova Scotia on Remembrance Day, 2017,
##    and plot the first one as a CTD.
n <- dc.argo(longitude=c(-65,-55), latitude=c(40,50),
             time=c("2017-11-11","2017-11-11"), destdir="~/data/argo")
a <- read.argo(n[1])
plotTS(as.ctd(a))

## 2. All profiles for a particular float.
N <- dc.argo(id="4902912", destdir="~/data/argo")
A <- read.argo(N)
plot(A, type="l") # trajectory

## End(Not run)