x2sys_init - Initialize data baes for track data files
x2sys_init TAG [ -Ddeffile ] [ -F ] [ -Gd|g ] [ -Idx[dy] ] [
-Rwest/east/south/north ] [ -V ] [ -Wsize ]
x2sys_init initializes a set of data bases that are particular to one
kind of track data. These data and their associated data bases are
given a short-hand notation called a system TAG. The TAG remembers set-
tings such as file format, whether the data are geographic or not, and
the binning resolution for track indexes. Running x2sys_init is a pre-
requisite to running x2sys_binlist which will create a crude represen-
tation of where data track go; this serves as input to the x2sys_put
too which updates the track data base. Then, x2sys_get can be used to
find which tracks and data are available inside a given region.
TAG The unique name of this data type system.
No space between the option flag and the associated arguments
-D Definition file for this data set. [x2sys.def]
-G Selects geographical coordinates. Append d for discontinuity at
the Dateline (makes longitude go from -180 to + 180) or g for
discontinuity at Greenwhich (makes longitude go from 0 to 360
-R xmin, xmax, ymin, and ymax specify the Region of interest. For
geographic regions, these limits correspond to west, east,
south, and north and you may specify them in decimal degrees or
in [+-]dd:mm[:ss.xxx][W|E|S|N] format. Append r if lower left
and upper right map coordinates are given instead of wesn. The
two shorthands -Rg -Rd stand for global domain (0/360 or
-180/+180 in longitude respectively, with -90/+90 in latitude).
For calendar time coordinates you may either give relative time
(relative to the selected TIME_EPOCH and in the selected
TIME_UNIT; append t to -JX|x), or absolute time of the form
[date]T[clock] (append T to -JX|x). At least one of date and
clock must be present; the T is always required. The date string
must be of the form [-]yyyy[-mm[-dd]] (Gregorian calendar) or
yyyy[-Www[-d]] (ISO week calendar), while the clock string must
be of the form hh:mm:ss[.xxx]. The use of delimiters and their
type and positions must be as indicated (however, input/output
and plotting formats are flexible).
-V Selects verbose mode, which will send progress reports to stderr
[Default runs "silently"].
-W Sets maximum time gap (in user units) allowed between points on
either side of a crossover [Default is Infinity].
lon a N 0 1 0 %10.5lf
lat a N 0 1 0 %9.5lf
time a N 0 1 0 %7.1lf
obs1 a N 0 1 0 %7.2lf
obs2 a N 0 1 0 %7.2lf
obs3 a N 0 1 0 %7.2lf
For ascii data the intype format is always a, Nan-proxy? should be Y if
there are certain values (e.g., -9999) that is used to represent miss-
ing data (NaNs). If so, the NaN-proxy values should be set accordingly
(otherwise it is ignored). The scale and offset is applied to the data
after it is read (first scaled, then offset), whereas the oformat is
used by some programs for formatted output.
Next we create the TAG and the databases for these line track files.
Assuming these are geographic and that we want to keep track of the
data distribution at a 1 x 1 degree resolution, we may run
x2sys_init LINE -V -G -Dline -R0/360/-90/90 -I1/1
where we have call the tag LINE. When x2sys tools will try to read your
line data files they will look in the file TAG_paths.txt for a list of
all the directories to examine. Therefore, create such a file (here
LINE_paths.txt) and stick the full paths to your data directories
there. All TAG-related files will be expected to be in the directory
pointed to by $X2SYS_HOME.
create tbf file(s)
Once the (empty) TAG database have been initialize we go through
a two- step process to populate them. First we run x2sys_binlist
on all our track files to create one (or more) multi-segment
track binindex files (tbf). These contain information on which
1x1 degree bins each track has visited and which observations
(in your case obs1, obs2, obs3) where actually observed (not all
tracks may have all the kinds of observations). Next, the track
binindex files are fed to x2sys_put which will insert the infor-
mation into the tag databases.
search Now you may use x2sys_get to find all the tracks within a cer-
tain sub-region, and optionally limit the search to those tracks
that have a particular combination of observables.
MGD77 or GMT
Definition files already exist for MGD77 files, the old *.gmt
files manipulated by the mgg supplements, and plain x,y,z
tracks. To initiate new track databases to be used with MGD77
data from NGDC, try
x2sys_init MGD77 -V -Dmgd77 -R0/360/-90/90 -I1/1
and the other steps are similar.
Let us pretend that your line files actually were binary files
with a 128-byte header structure (to be skipped) followed by the
data records and where lon, lat, time are double precision num-
time d N 0 1 0 %7.1lf
obs1 h Y 32000 0.1 0 %6.1lf
obs2 h Y 32000 0.1 0 %6.1lf
obs3 h N 0 0.1 0 %6.1lf
The rest of the steps are identical. The accepted intype flags
are c fir sugned 1-byte character (-127,+128), u for unsigned
byte (0-255), h for signed 2-byte integers (-32767,+32767), i
for signed 4-byte integers (-2,147,483,648,+2,147,483,648), f
for 4-byte floating points and d for 8-byte double precision
x2sys_binlist(GMTMANSECTION) x2sys_get(GMTMANSECTION) x2sys_put(GMTMAN-
GMT4.0 1 Oct 2004 X2SYS_INIT(GMTMANSECTION)
Man(1) output converted with