xenial (1) grdclip.1gmt.gz

NAME

       grdclip - Clip the range of grids

SYNOPSIS

       grdclip  ingrid  outgrid  [  region ] [ ahigh/above ] [ blow/below ] [ ilow/high/between ] [ rold/new ] [
       [level] ]

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

DESCRIPTION

       grdclip will set values < low to below and/or values > high to above. You can also specify  one  or  more
       intervals  where  all values should be set to IT(between), or replace individual values.  Such operations
       are useful when you want all of a continent or an ocean to fall into one color or  gray  shade  in  image
       processing,  when  clipping  of  the  range  of  data values is required, or for reclassification of data
       values.  above, below, between, old and new can be any number or even NaN (Not a Number). You must choose
       at least one of the -S options. Use -R to only extract a subset of the ingrid file.

REQUIRED ARGUMENTS

       ingrid The input 2-D binary grid file.

       -Goutgrid
              outgrid is the modified output grid file.

OPTIONAL ARGUMENTS

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

       -Sahigh/above
              Set all data[i] > high to above.

       -Sblow/below
              Set all data[i] < low to below.

       -Silow/high/between
              Set all data[i] >= low and <= high to between.  Repeat the option for as  many  intervals  as  are
              needed.

       -Srold/new
              Set  all  data[i]  ==  old  to  new.  This is mostly useful when your data are known to be integer
              values.  Repeat the option for as many replacements as are needed.

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

       -^ 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.

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 1- or 2-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.
       In  case  the  two  characters  id  is not provided, as in =/scale than a id=nf is assumed.  When reading
       grids, the format is generally automatically recognized. If not, the same suffix can be  added  to  input
       grid  file names. See grdconvert and Section grid-file-format 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
       grdconvert and Sections modifiers-for-CF and grid-file-format of the GMT Technical Reference and Cookbook
       for more information, particularly on how to read splices of 3-, 4-, or 5-dimensional grids.

EXAMPLES

       To set all values > 70 to NaN and all values < 0 to 0 in file data.nc:

              gmt grdclip data.nc -Gnew_data.nc -Sa70/NaN -Sb0/0 -V

       To  reclassify  all  values  in  the  25-30 range to 99, those in 35-39 to 55, exchange 17 for 11 and all
       values < 10 to 0 in file classes.nc, try

              gmt grdclip classes.nc -Gnew_classes.nc -Si25/30/99 -Si35/39/55 -Sr17/11 -Sb10/0 -V

SEE ALSO

       gmt, grdlandmask, grdmask, grdmath, grd2xyz, xyz2grd

COPYRIGHT

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