Ubuntu Manpage: grdclip - Clip the range of grids

Provided by: gmt-common_5.2.1+dfsg-3build1_all

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

COPYRIGHT

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

5.2.1                                           January 28, 2016                                   GRDCLIP(1gmt)