Provided by: gmt_4.5.11-1build1_amd64 bug

NAME

       grdcut - Extract a subregion out of a grid file

SYNOPSIS

       grdcut  input_file.grd -Goutput_file.grd -Rwest/east/south/north[r] [ -V ] [ -Z[n]min/max]
       ] [ -f[i|o]colinfo ]

DESCRIPTION

       grdcut will produce a new output_file.grd file which is  a  subregion  of  input_file.grd.
       The  subregion  is  specified  with  -R as in other programs; the specified range must not
       exceed  the  range  of  input_file.grd.   If  in  doubt,  run  grdinfo  to  check   range.
       Alternatively,  define  the  subregion  indirectly  via  a range check on the node values.
       Complementary to grdcut there is grdpaste, which will join together two grid files along a
       common edge.

       input_file.grd
              this is the input .grd format file.

       -Goutput_file.grd
              this is the output .grd format file.

       -R     xmin, xmax, ymin, and ymax specify the Region of interest.  For geographic regions,
              these limits correspond to west, east, south, and north 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, specify the name  of  an  existing  grid
              file  and  the  -R  settings  (and grid spacing, if applicable) are copied from the
              grid.  For calendar  time  coordinates  you  may  either  give  (a)  relative  time
              (relative  to  the  selected  TIME_EPOCH and in the selected TIME_UNIT; append t to
              -JX|x), or (b) absolute time of the form [date]T[clock] (append T  to  -JX|x).   At
              least  one  of  date and clock must be present; the T is always required.  The date
              string must be of the form [-]yyyy[-mm[-dd]] (Gregorian calendar) or yyyy[-Www[-d]]
              (ISO  week  calendar),  while  the clock string must be of the form hh:mm:ss[.xxx].
              The use of delimiters and their type and positions must  be  exactly  as  indicated
              (however,  input, output and plot formats are customizable; see gmtdefaults).  This
              defines the subregion to be cut out.

OPTIONS

       -V     Selects verbose mode, which will send progress  reports  to  stderr  [Default  runs
              "silently"].

       -Z     Determine the new rectangular region so that all nodes outside this region are also
              outside the given z-range [-inf/+inf].  To indicate no limit on min or max, specify
              a  hyphen  (-).   Normally,  any  NaNs  encountered are simply skipped.  Use -Zn to
              consider a NaN to be outside the z-range.

       -f     Special formatting of input and/or output  columns  (time  or  geographical  data).
              Specify  i  or  o  to  make  this apply only to input or output [Default applies to
              both].  Give one or more columns (or column ranges) separated by commas.  Append  T
              (absolute calendar time), t (relative time in chosen TIME_UNIT since TIME_EPOCH), x
              (longitude), y (latitude), or f (floating point) to each  column  or  column  range
              item.  Shorthand -f[i|o]g means -f[i|o]0x,1y (geographic coordinates).

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 "packing" of grids, writing out floating point
       data as 2- or 4-byte integers. To specify the precision, scale and offset, the user should
       add  the  suffix =id[/scale/offset[/nan]], where id is a two-letter identifier of the grid
       type and precision, and scale and offset are  optional  scale  factor  and  offset  to  be
       applied  to  all  grid  values,  and nan is the value used to indicate missing data.  When
       reading grids, the format is generally automatically recognized. If not, the  same  suffix
       can  be  added  to  input grid file names.  See grdreformat(1) and Section 4.17 of the GMT
       Technical Reference and Cookbook for more information.

       When reading a netCDF file that contains multiple grids, GMT will read,  by  default,  the
       first  2-dimensional  grid  that  can  find in that file. To coax GMT into reading another
       multi-dimensional variable in the grid file, append  ?varname  to  the  file  name,  where
       varname  is the name of the variable. Note that you may need to escape the special meaning
       of ? in your shell program by putting a backslash in  front  of  it,  or  by  placing  the
       filename and suffix between quotes or double quotes.  The ?varname suffix can also be used
       for output grids to specify  a  variable  name  different  from  the  default:  "z".   See
       grdreformat(1)  and  Section  4.18  of  the  GMT Technical Reference and Cookbook for more
       information, particularly on how to read splices of 3-, 4-, or 5-dimensional grids.

GEOGRAPHICAL AND TIME COORDINATES

       When the output grid  type  is  netCDF,  the  coordinates  will  be  labeled  "longitude",
       "latitude", or "time" based on the attributes of the input data or grid (if any) or on the
       -f or -R options. For example, both -f0x -f1t  and  -R  90w/90e/0t/3t  will  result  in  a
       longitude/time grid. When the x, y, or z coordinate is time, it will be stored in the grid
       as relative time since epoch as specified by TIME_UNIT and TIME_EPOCH in the  .gmtdefaults
       file  or  on  the command line.  In addition, the unit attribute of the time variable will
       indicate both this unit and epoch.

EXAMPLES

       Suppose you have used surface to grid ship gravity in the region between 148E -  162E  and
       8N  -  32N, and you do not trust the gridding near the edges, so you want to keep only the
       area between 150E - 160E and 10N - 30N, then:

       grdcut grav_148_162_8_32.nc -G grav_150_160_10_30.nc -R 150/160/10/30  -V  To  return  the
       subregion  of  a grid such that any boundary strips where all values are entirely above 0,
       try

       grdcut bathy.nc -G trimmed_bathy.nc -Z-/0 -V

SEE ALSO

       grdpaste(1), grdinfo(1), GMT(1)