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grd2xyz(1)                            GMT                           grd2xyz(1)




NAME

       grd2xyz - Convert grid file to data table


SYNOPSIS

       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.


DESCRIPTION

       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.


REQUIRED ARGUMENTS

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


OPTIONAL ARGUMENTS

       -C[f|i]
              Replace  the x- and y-coordinates on output with the correspond-
              ing 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 a|)
              Specify the region of interest. Using the -R option will  select
              a  subsection of the grid. If this subsection exceeds the bound-
              aries of the grid, only the common region will be output.

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

       -W[a|weight]
              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 represents.

       -Z[flags]
              Write a 1-column ASCII [or binary] table. Output will  be  orga-
              nized  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):

              o a ASCII representation of a single item per record

              o c int8_t, signed 1-byte character

              o u uint8_t, unsigned 1-byte character

              o h int16_t, short 2-byte integer

              o H uint16_t, unsigned short 2-byte integer

              o i int32_t, 4-byte integer

              o I uint32_t, unsigned 4-byte integer

              o l int64_t, long (8-byte) integer

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

              o f 4-byte floating point single precision

              o 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 a|)
              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 a|)
              Replace  input  columns  that  equal  nodata with NaN and do the
              reverse on output.

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

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

       -s[cols][a|r] (more a|)
              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  explana-
              tion  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.


ASCII FORMAT PRECISION

       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  FOR-
       MAT_DATE_OUT and FORMAT_CLOCK_OUT, whereas general floating point  val-
       ues are formatted according to FORMAT_FLOAT_OUT. Be aware that the for-
       mat 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 set-
       ting.


GRID FILE FORMATS

       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  apackinga of grids, writing out floating point
       data as 1- or 2-byte integers. (more a|)


TIME COORDINATES

       Time coordinates in netCDF grids, be it the x, y, or z coordinate, will
       be  recognized  as  such.  The  variableas  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, respec-
       tively.


EXAMPLES

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

              gmt grd2xyz hawaii_grv.nc > hawaii_grv.xyz

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

              gmt grd2xyz raw_data.nc -ZTLf > hawaii_grv.b


SEE ALSO

       gmt.conf(5), gmt(1), grdedit(1), grdconvert(1), xyz2grd(1)


COPYRIGHT

       2017, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe



5.4.2                            Jun 24, 2017                       grd2xyz(1)

gmt5 5.4.2 - Generated Wed Jun 28 18:10:40 CDT 2017
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