X2SYS_DATALIST(1gmt)					       Generic Mapping Tools					      X2SYS_DATALIST(1gmt)

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 miss-
	      ing 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). Alterna-
	      tively, 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.  Option-
	      ally, 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 -TGMT > 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 -TTRK -Flon,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 cor-
       rection 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 fol-
       lowing  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)

GMT 4.5.7							    15 Jul 2011 					      X2SYS_DATALIST(1gmt)