Provided by: gmt-common_5.4.5+dfsg-2_all bug


       grd2xyz - Convert grid file to data table


       grd2xyz  grid [  -C[f|i] ] [  -Rregion ] [  -V[level] ] [  -W[a|weight] ] [  -Z[flags] ] [
       -bobinary ] [ -dnodata ] [ -fflags ] [ -ho[n] ] [ -oflags ] [ -sflags ]

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


       grd2xyz reads one or more binary 2-D grid files and writes out xyz-triplets in  ASCII  [or
       binary]  format  to  standard  output.  Modify the precision of the ASCII output format by
       editing the FORMAT_FLOAT_OUT parameter in your gmt.conf file or use  --D_FORMAT=format  on
       the  command line, or choose binary output using single or double precision storage. As an
       option you may output z-values without the (x,y) coordinates; see -Z below.


       grid   Names of 2-D binary grid files to be converted. (See GRID FILE FORMATS below.)


              Replace the x- and y-coordinates on output with the corresponding  column  and  row
              numbers. These start at 0 (C-style counting); append f to start at 1 (Fortran-style
              counting). Alternatively, append i to write just the two columns index and z, where
              index is the 1-D indexing that GMT uses when referring to grid nodes.

       -Rxmin/xmax/ymin/ymax[+r][+uunit] (more ...)
              Specify the region of interest. Using the -R option will select a subsection of the
              grid. If this subsection exceeds the boundaries of the grid, only the common region
              will be output.

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

              Write  out  x,y,z,w, where w is the supplied weight (or 1 if not supplied) [Default
              writes x,y,z only].  Choose -Wa to compute weights equal  to  the  area  each  node

              Write a 1-column ASCII [or binary] table. Output will be organized according to the
              specified ordering convention contained in flags.  If data  should  be  written  by
              rows,  make  flags start with T (op) if first row is y = ymax or B (ottom) if first
              row is y = ymin. Then, append L or R to indicate that first element should start at
              left  or  right  end  of  row.  Likewise  for  column formats: start with L or R to
              position first column, and then append T or B to position first element in  a  row.
              For gridline registered grids: If grid is periodic in x but the written data should
              not contain the (redundant) column at x = xmax, append x. For grid periodic  in  y,
              skip  writing the redundant row at y = ymax by appending y. If the byte-order needs
              to be swapped, append w. Select one of several data types (all binary except a):

              · a ASCII representation of a single item per record

              · c int8_t, signed 1-byte character

              · u uint8_t, unsigned 1-byte character

              · h int16_t, short 2-byte integer

              · H uint16_t, unsigned short 2-byte integer

              · i int32_t, 4-byte integer

              · I uint32_t, unsigned 4-byte integer

              · l int64_t, long (8-byte) integer

              · L uint64_t, unsigned long (8-byte) integer

              · f 4-byte floating point single precision

              · d 8-byte floating point double precision

              Default format is scanline orientation of ASCII numbers: -ZTLa.  Note that -Z  only
              applies to 1-column output.

       -bo[ncols][type] (more ...)
              Select  native  binary  output.  [Default  is  3].  This option only applies to xyz
              output; see -Z for z table output.

       -d[i|o]nodata (more ...)
              Replace input columns that equal nodata with NaN and do the reverse on output.

       -f[i|o]colinfo (more ...)
              Specify data types of input and/or output columns. See also TIME COORDINATES below.
              -h  Output  1  header  record  based  on information in the first grid file header.
              Ignored if binary output is selected. [Default is no header].

       -ocols[,...] (more ...)
              Select output columns (0 is first column).

       -s[cols][a|r] (more ...)
              Set handling of NaN records.

       -^ 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.


       The  ASCII  output formats of numerical data are controlled by parameters in your gmt.conf
       file. Longitude and latitude are formatted according to FORMAT_GEO_OUT, absolute  time  is
       under  the control of FORMAT_DATE_OUT and FORMAT_CLOCK_OUT, whereas general floating point
       values are formatted according to FORMAT_FLOAT_OUT. Be aware that the format in effect can
       lead  to loss of precision in ASCII output, which can lead to various problems downstream.
       If you find the output is not written with enough precision, consider switching to  binary
       output (-bo if available) or specify more decimals using the FORMAT_FLOAT_OUT setting.


       By  default  GMT  writes  out grid as single precision floats in a COARDS-complaint netCDF
       file format. However, GMT is able to produce grid files in many other commonly  used  grid
       file formats and also facilitates so called "packing" of grids, writing out floating point
       data as 1- or 2-byte integers. (more ...)


       Time coordinates in netCDF grids, be it the x, y, or z coordinate, will be  recognized  as
       such.  The variable's unit attribute is parsed to determine the unit and epoch of the time
       coordinate in the grid. Values are then converted to the internal time system specified by
       TIME_UNIT  and  TIME_EPOCH in the gmt.conf file or on the command line. The default output
       is relative time in that time system, or absolute time when using the option  -f0T,  -f1T,
       or -f2T for x, y, or z coordinate, respectively.


       To edit individual values in the 5' by 5' file, dump the .nc to ASCII:

              gmt grd2xyz >

       To  write  a  single  precision  binary  file  without  the  x,y  positions  from the file file, using scanline orientation, run

              gmt grd2xyz -ZTLf > hawaii_grv.b


       gmt.conf, gmt, grdedit, grdconvert, xyz2grd


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