NAME

       x2sys_datalist - A generic data-extractor for ASCII or binary files

SYNOPSIS

       x2sys_datalist track(s) -TTAG [ -A ] [ -Fname1,name2,... ] [ -H[i][nrec] ] [ -L[corrtable]
       ] [ -Rwest/east/south/north[r] ]  [ -S ] [  -V  ]  [  -bo[s|S|d|D[ncol]|c[var1/...]]  ]  [
       -m[flag] ]

DESCRIPTION

       x2sys_datalist reads one or more files and produces a single ASCII [or binary] table.  The
       files can be of any format, which must be described and passed with the  -T  option.   You
       may limit the output to a geographic region, and insist that the output from several files
       be separated by a multiple segment header.  Only the named  data  fields  will  be  output
       [Default selects all columns].

       tracks Can  be  one  or  more  ASCII,  native binary, or COARDS netCDF 1-D data files.  To
              supply the data files via a text file with a  list  of  tracks  (one  per  record),
              specify  the name of the track list after a leading equal-sign (e.g., =tracks.lis).
              If the names are missing their file extension we will append the  suffix  specified
              for  this TAG.  Track files will be searched for first in the current directory and
              second in all directories listed in $X2SYS_HOME/TAG/TAG_paths.txt (if  it  exists).
              [If  $X2SYS_HOME  is  not set it will default to $GMT_SHAREDIR/x2sys]. (Note: MGD77
              files will also be looked for via MGD77_HOME/mgd77_paths.txt and *.gmt  files  will
              be searched for via $GMT_SHAREDIR/mgg/gmtfile_paths).

       -T     Specify the x2sys TAG which tracks the attributes of this data type.

OPTIONS

       No space between the option flag and the associated arguments.

       -A     Eliminate  COEs  by  distributing  the  COE between the two tracks in proportion to
              track weight.  These (dist, adjustment) spline knots files for each track and  data
              column  are  called  track.column.adj and are expected to be in the $X2SYS_HOME/TAG
              directory.  The adjustments are only applied if the corresponding adjust  file  can
              be found [No residual adjustments]

       -F     Give a comma-separated sub-set list of column names defined in the definition file.
              [Default selects all data columns].

       -H     Input file(s) has header record(s).  If used, the default number of header  records
              is  N_HEADER_RECS.   Use -Hi if only input data should have header records [Default
              will write out header records if the input data have them]. Blank lines  and  lines
              starting with # are always skipped.

       -L     Apply  optimal corrections to columns where such corrections are available.  Append
              the correction table to use [Default uses the correction table  TAG_corrections.txt
              which  is  expected to reside in the $X2SYS_HOME/TAG directory].  For the format of
              this file, see CORRECTIONS below.

       -R     west, east, south, and north specify the Region of interest, 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 w/e/s/n.   The  two
              shorthands  -Rg  and  -Rd stand for global domain (0/360 and -180/+180 in longitude
              respectively, with -90/+90 in latitude). Alternatively,  specify  the  name  of  an
              existing grid file and the -R settings (and grid spacing, if applicable) are copied
              from the grid.  For Cartesian data  just  give  xmin/xmax/ymin/ymax.   This  option
              limits the COEs to those that fall inside the specified domain.

       -S     Suppress output records where all the data columns are NaN [Default will output all
              records].

       -V     Selects verbose mode, which will send progress  reports  to  stderr  [Default  runs
              "silently"].

       -bo    Selects  binary  output.   Append  s  for single precision [Default is d (double)].
              Uppercase S or D will force byte-swapping.  Optionally, append ncol, the number  of
              desired columns in your binary output file.

       -m     Output  a  multisegment header between data from each track.  Note this option does
              not imply anything about the input file;  that  information  is  conveyed  via  the
              system tag (-T).

EXAMPLES

       To  extract  all  data from the old-style MGG supplement file c2104.gmt, recognized by the
       tag GMT:

       x2sys_datalist c2104.gmt -T GMT > myfile

       To make lon,lat, and depth input for blockmean and surface using all the files  listed  in
       the  file  tracks.lis  and  define  by  the tag TRK, but only the data that are inside the
       specified area, and make output binary, run

       x2sys_datalist =tracks.lis -T TRK -F lon,lat,depth -R-40/-30/25/35 -bo > alltopo_bin.xyz

CORRECTIONS

       The correction table is an ASCII file with coefficients and parameters needed to carry out
       corrections.   This  table  is usually produced by x2sys_solve.  Comment records beginning
       with # are allowed.  All correction records are of the form

       trackID observation correction

       where trackID is the track name, observation is one of the abbreviations for  an  observed
       field  contained  in  files  under this TAG, and correction consists of one or more white-
       space-separated terms that will be subtracted from the observation  before  output.   Each
       term must have this exact syntax:

       factor[*[function]([scale](abbrev[-origin]))[^power]]

       where  terms  in  brackets  are optional (the brackets themselves are not used but regular
       parentheses must be used exactly as indicated).  No  spaces  are  allowed  except  between
       terms.  The factor is the amplitude of the basis function, while the optional function can
       be one of sin, cos, or exp. The optional scale and origin can be  used  to  translate  the
       argument  (before  giving it to the optional function).  The argument abbrev is one of the
       abbreviations for columns known to this TAG.  However, it can also be  one  of  the  three
       auxiliary  terms  dist (for along-track distances), azim for along-track azimuths, and vel
       (for along-track speed); these are all sensitive to the  -C  and  -N  settings  used  when
       defining  the TAB; furthermore, vel requires time to be present in the data.  If origin is
       given as T it means that we should replace it with the value of abbrev for the very  first
       record  in  the file (this is usually only done for time).  If the first data record entry
       is NaN we revert origin to zero.  Optionally, raise the entire  expression  to  the  given
       power,  before  multiplying  by  factor.   The  following  is  an  example  of  fictitious
       corrections to the track ABC, implying the z column should have a  linear  trend  removed,
       the  field  obs  should  be corrected by a strange dependency on latitude, weight needs to
       have 1 added (hence correction is given as -1), and fuel should be  reduced  by  a  linear
       distance term:

       ABC z     7.1  1e-4*((time-T))
       ABC obs   0.5*exp(-1e-3(lat))^1.5
       ABC weight     -1
       ABC fuel 0.02*((dist))

SEE ALSO

       blockmean(1),   GMT(1),   surface(1),   x2sys_init(1),   x2sys_datalist(1),  x2sys_get(1),
       x2sys_list(1), x2sys_put(1), x2sys_report(1), x2sys_solve(1)