readArgos: Read Argos "DAT" files
Description
Return a (Spatial) data frame of location records from raw Argos files.
Multiple files may be read, and each set of records is appended to
the data frame in turn. Basic validation of the data is enforced by
default.Usage
readArgos(x, correct.all = TRUE, dtFormat = "%Y-%m-%d %H:%M:%S", tz = "GMT", duplicateTimes.eps = 0.01, p4 = "+proj=longlat +datum=WGS84")
Arguments
x
vector of file names of Argos data
correct.all
logical - enforce validity of data as much as possible? (see Details)
dtFormat
the DateTime format used by the Argos data "date" and "time" pasted together
tz
timezone - GMT/UTC is assumed
duplicateTimes.eps
what is the tolerance for times being duplicate?
p4
PROJ.4 projection string, "+proj=longlat" is assumed
Value
- A
trip object, if all goes well, or simply a SpatialPointsDataFrame.
Warning
This works on some Argos files I have seen, it is not
a guaranteed method and is in no way linked officially to Argos.Details
Basic validation checks for class trip are made, and enforced based on
correct.all:
No duplicate records in the data, these are simply removed.
Records are ordered by DateTime ("date", "time", "gmt") within ID ("ptt").
No duplicate DateTime values within ID are allowed: to enforce this the time
values are moved forward by one second - this is done recursively and is not
robust.
If validation fails the function will return a SpatialPointsDataFrame.
Files that are not obviously of the required format are skipped.
Argos location quality data "class" are ordered, assuming that the available
levels is levels = c("Z", "B", "A", "0", "1", "2", "3").
A projection string is added to the data, assuming the PROJ.4 longlat - if any
longitudes are greater than 360 the PROJ.4 argument "+over" is added.References
The Argos data documentation is at
http://www.cls.fr/welcome_en.html. Specific details on the PRV ("provide data")
format can be found here http://www.cls.fr/manuel/html/chap4/chap4_4_8.htm.