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.
readArgos(
x,
correct.all = TRUE,
dtFormat = "%Y-%m-%d %H:%M:%S",
tz = "GMT",
duplicateTimes.eps = 0.01,
p4 = "+proj=longlat +ellps=WGS84",
verbose = FALSE,
read_alt = NULL,
...
)readDiag(x, return_trip = FALSE, read_alt = 1L, ...)
readArgos
returns a trip
object, if all goes well, or simply a
SpatialPointsDataFrame-class
.
readDiag
returns a data.frame
with 8 columns:
lon1
,lat1
first pair of coordinates
lon1
,lat1
second pair of coordinates
gmt DateTimes as POSIXct
id Platform Transmitting Terminal (PTT) ID
lq Argos location quality class
iq some other thing
vector of file names of Argos "DAT" or "DIAG" files.
logical - enforce validity of data as much as possible? (see Details)
the DateTime format used by the Argos data "date" and "time" pasted together
timezone - GMT/UTC is assumed
what is the tolerance for times being duplicate?
PROJ.4 projection string, "+proj=longlat +ellps=WGS84" is assumed
if TRUE, details on date-time adjustment is reported
is NULL
by default, with longitude and latitude read from the PRV message, if 1
or 2
then attempt is made to read the alternative locations (but these are not always present)
reserved for future use
for readDiag()
if TRUE
will return a trip object, use read_alt
to control the location
This works on some Argos files I have seen.
readArgos
performs 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-class
. 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.
readDiag
simply builds a data.frame
.
With read_alt
the default value NULL
returns the PRV location as-is. Some files may have
a standardized location, and a dummy. If read_alt
is set to 1 or 2 the corresponding "alternative"
location is returned. 1 is a standardized location corresponding to the original PRV message, and 2 is a
"dummy" location.
The Argos data documentation was (ca. 2003) at http://www.argos-system.org/manual. Specific details on the PRV ("provide data") format were found in Chapter 4_4_8, originally at 'http://www.cls.fr/manuel/html/chap4/chap4_4_8.htm'.
trip
, SpatialPointsDataFrame-class
,
adjust.duplicateTimes
, for manipulating these data, and
argos.sigma
for relating a numeric value to Argos quality
"classes".
sepIdGaps
for splitting the IDs in these data on some minimum
gap.
order
, duplicated
, , ordered
for
general manipulation of this type.
argosfile <-
system.file("extdata/argos/98feb.dat", package = "trip", mustWork = TRUE)
argos <- readArgos(argosfile)
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