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[][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.

       binary files
              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
              floating points.


       x2sys_binlist(GMTMANSECTION) x2sys_get(GMTMANSECTION) x2sys_put(GMTMAN-

GMT4.0                            1 Oct 2004         X2SYS_INIT(GMTMANSECTION)

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