NAME

       x2sys_list - Extract subset from crossover data base

SYNOPSIS

       x2sys_list  column TAG [ coedbase.txt ] [ asymm_max ] [  ] [ acdhiInNtTvwxyz ] [ [list] ] [ [corrtable] ]
       [ nx_min ] [ e|i ] [ region ] [ track ] [ [level] ] [ [list] ] [ -bo<binary> ]

       Note: No space is allowed between the option flag and the associated arguments.

DESCRIPTION

       x2sys_list will read the crossover ASCII data base coedbase.txt (or stdin) and extract a  subset  of  the
       crossovers based on the other arguments. The output may be ASCII or binary.

REQUIRED ARGUMENTS

       -Ccolumn
              Specify  which  data  column  you  want to process. Crossovers related to this column name must be
              present in the crossover data base.

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

OPTIONAL ARGUMENTS

       coedbase.txt
              The name of the input ASCII crossover error data base as produced by x2sys_cross. If not given  we
              read standard input instead.

       -Aasymm_max
              Specifies  maximum  asymmetry  in the distribution of crossovers relative to the mid point in time
              (or distance, if not time is available). Asymmetry is computed as (n_right  -  n_left)/(n_right  +
              n_left), referring the the number of crossovers that falls in the left or right half of the range.
              Symmetric  distributions  will  have  values  close to zero. If specified, we exclude tracks whose
              asymmetry exceeds the specify cutoff in absolute value [1, i.e., include all].

       -E     Enhance ASCII output by writing GMT segment headers with name of the two tracks  and  their  total
              number of cross-overs [no segment headers].

       -FacdhiInNtTvwxyz
              Specify  your  desired  output  using any combination of acdhiInNtTvwxyz, in any order. Do not use
              space between the letters, and note your selection is case-sensitive. The output will be ASCII (or
              binary, -bo) columns of values. Description of codes: a  is  the  angle  (<  90)  defined  by  the
              crossing tracks, c is crossover value of chosen observation (see -C), d is distance along track, h
              is  heading  along  track, i is the signed time interval between the visit at the crossover of the
              two tracks involved, I is same as i but is unsigned, n is the names of the two tracks, N is the id
              numbers of the two tracks, t is time along track in dateTclock format (NaN if not available), T is
              elapsed time since start of track along track (NaN if not available), v is speed along track, w is
              the composite weight, x is x-coordinate (or longitude), y is y-coordinate (or latitude), and z  is
              observed  value  (see  -C)  along  track. If -S is not specified then d,h,n,N,t,T,v results in two
              output columns each: first for track one and next for track two (in lexical order of track names);
              otherwise, they refer to the specified track only (except for n,N which then refers to  the  other
              track).  The  sign  convention  for  c,i  is  track  one  minus track two (lexically sorted). Time
              intervals will be returned according to the TIME_UNIT GMT defaults setting.

       -I[list]
              Name of ASCII file with a list of track names (one  per  record)  that  should  be  excluded  from
              consideration [Default includes all tracks].

       -L[corrtable]
              Apply  optimal  corrections  to the chosen observable. 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 x2sys_solve.

       -Nnx_min
              Only  report  data  from  pairs  that  generated  at least nx_min crossovers between them [use all
              pairs].

       -Qe|i  Append e for external crossovers or i for internal crossovers only [Default is all crossovers].

       -R[unit]west/east/south/north[/zmin/zmax][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 for grid
              creation,  give  Rcodelon/lat/nx/ny, where code is a 2-character combination of L, C, R (for left,
              center, or right) and T, M, B for top, middle, or bottom. e.g., BL for lower left.  This indicates
              which point on a rectangular region the lon/lat coordinate refers to, and the grid  dimensions  nx
              and  ny  with  grid  spacings  via  -I is used to create the corresponding region.  Alternatively,
              specify the name of an existing grid file and the -R settings (and grid  spacing,  if  applicable)
              are  copied  from the grid. Using -Runit expects projected (Cartesian) coordinates compatible with
              chosen -J and we inversely  project  to  determine  actual  rectangular  geographic  region.   For
              perspective  view (-p), optionally append /zmin/zmax.  In case of perspective view (-p), a z-range
              (zmin, zmax) can be appended to indicate the third dimension. This needs  to  be  done  only  when
              using  the -Jz option, not when using only the -p option. In the latter case a perspective view of
              the plane is plotted, with no third dimension. For Cartesian data just  give  xmin/xmax/ymin/ymax.
              This option bases the statistics on those COE that fall inside the specified domain.

       -Strack
              Name  of  a  single  track.  If  given we restrict output to those crossovers involving this track
              [Default output is crossovers involving any track pair].

       -V[level] (more ...)
              Select verbosity level [c].

       -W[list]
              Name of ASCII file with a list of track names and their relative weights (one  track  per  record)
              that  should  be  used to calculate the composite crossover weight (output code w above). [Default
              sets weights to 1].

       -bo[ncols][type] (more ...)
              Select native binary output.

       -^ or just -
              Print a short message about the syntax of the command, then exits (NOTE: on Windows use just -).

       -+ or just +
              Print an extensive usage (help) message, including the explanation of any  module-specific  option
              (but not the GMT common options), then exits.

       -? or no arguments
              Print a complete usage (help) message, including the explanation of options, then exits.

       --version
              Print GMT version and exit.

       --show-datadir
              Print full path to GMT share directory and exit.

EXAMPLES

       To  find all the magnetic crossovers associated with the tag MGD77 from the file COE_data.txt, restricted
       to occupy a certain region in the south Pacific, and return location, time, and crossover value, try

              gmt x2sys_list COE_data.txt -V -TMGD77 -R180/240/-60/-30 -Cmag -Fxytz > mag_coe.txt

       To find all the faa crossovers globally that involves track 12345678 and output time since start  of  the
       year, using a binary double precision format, try

              gmt x2sys_list COE_data.txt -V -TMGD77 -Cfaa -S12345678 -FTz -bod > faa_coe.b

SEE ALSO

       x2sys_binlist, x2sys_cross, x2sys_datalist, x2sys_get, x2sys_init, x2sys_put, x2sys_report, x2sys_solve

COPYRIGHT

       2015, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe

5.2.1                                           January 28, 2016                                X2SYS_LIST(1gmt)