Provided by: gmt-common_5.4.5+dfsg-1_all bug


       x2sys_list - Extract subset from crossover data base


       x2sys_list  -Ccolumn  -TTAG [ coedbase.txt ] [  -Aasymm_max ] [  -E ] [  -FacdhiInNtTvwxyz
       ] [  -I[list] ] [  -L[corrtable] ] [  -Nnx_min ] [  -Qe|i ] [  -Rregion ] [  -Strack  ]  [
       -V[level] ] [  -W[list] ] [ -bobinary ]

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


       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.


              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.


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

              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].

              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.

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

              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

              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

              west, east, south, and north specify the region of interest, 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  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.
              Appending  +uunit  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.

              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].

              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
              just use -).

       -+ 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 all options,
              then exits.


       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


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


       2019, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe