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grdedit(1)                            GMT                           grdedit(1)




NAME

       grdedit - Modify header or content of a grid


SYNOPSIS

       grdedit       grid      [       -A      ]      [       -C      ]      [
       -D[+xxname][+yyname][+zzname][+sscale][+ooffset][+ninvalid][+tti-
       tle][+rremark]  ] [  -E[a|h|l|r|t|v] ] [  -Goutgrid ] [  -Jparameters ]
       [  -Ntable ] [  -Rregion ] [  -S ] [  -T ] [  -V[level] ] [ -bibinary ]
       [ -dinodata ] [ -eregexp ] [ -fflags ] [ -:[i|o] ]

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


DESCRIPTION

       grdedit reads the header information in a  binary  2-D  grid  file  and
       replaces  the  information with values provided on the command line [if
       any]. As an option, global, geographical grids (with 360 degrees longi-
       tude  range)  can be rotated in the east-west direction, and individual
       nodal values can be replaced from a table of x, y,  z  values.  grdedit
       only  operates on files containing a grid header. Note: If it is impor-
       tant to retain the original data you should use -G to save the modified
       grid to a new file.


REQUIRED ARGUMENTS

       grid   Name  of  the  2-D  grid  file to modify. (See GRID FILE FORMATS
              below).


OPTIONAL ARGUMENTS

       -A     If necessary, adjust the fileas x_inc, y_inc  to  be  compatible
              with  its domain (or a new domain set with -R). Older grid files
              (i.e., created prior to GMT 3.1) often  had  excessive  slop  in
              x_inc,  y_inc  and  an  adjustment is necessary. Newer files are
              created correctly.

       -C     Clear the command history from the grid header.

       -D[+xxname][+yyname][+zzname][+sscale][+ooffset][+ninvalid][+tti-
       tle][+rremark]
              Give one or more combinations for  values  xname,  yname,  zname
              (give  the  names of those variables and in square bracket their
              units, e.g., adistance [km]a), scale (to  multiply  grid  values
              after  read  [normally 1]), offset (to add to grid after scaling
              [normally 0]),  invalid  (a  value  to  represent  missing  data
              [NaN]),  title  (anything  you  like),  and remark (anything you
              like). Items not listed will remain  untouched.   Give  a  blank
              name  to  completely  reset  a particular string.  Use quotes to
              group texts with more than one word.  Note that  for  geographic
              grids (-fg) xname and yname are set automatically.

       -E[a|h|l|r|t|v]
              Transform  the  grid  in  one of six ways and (for l|r|t) inter-
              change the x and y information: -Ea will rotate the grid  around
              180    degrees,    -Eh   will   flip   the   grid   horizontally
              (left-to-right),  -El  will   rotate   the   grid   90   degrees
              counter-clockwise  (left),  -Er  will rotate the grid 90 degrees
              clockwise (right), -Et will transpose the  grid  [Default],  -Ev
              will  flip  the  grid  vertically (top-to-bottom).  Incompatible
              with the other options (except -G).

       -Goutgrid
              Normally, grdedit will overwrite the existing grid with the mod-
              ified  grid.  Use -G to write the modified grid to the file out-
              grid instead.

       -Jparameters (more a|)
              Select map projection. Use the -J syntax to save  the  georefer-
              encing  info  as  CF-1  compliant metadata in netCDF grids. This
              metadata will be recognized by GDAL.

       -Ntable
              Read the ASCII (or binary; see -bi) file table and  replace  the
              corresponding  nodal values in the grid with these x,y,z values.

       -Rxmin/xmax/ymin/ymax[+r][+uunit] (more a|)
              Specify the region of interest.  The  new  w/e/s/n  values  will
              replace  those  in  the  grid,  and  the x_inc, y_inc values are
              adjusted, if necessary.

       -S     For global, geographical grids only. Grid values will be shifted
              longitudinally according to the new borders given in -R.

       -T     Make  necessary changes in the header to convert a gridline-reg-
              istered grid to a pixel-registered grid, or  vice-versa.   Basi-
              cally, gridline-registered grids will have their domain extended
              by half the x- and y-increments whereas  pixel-registered  grids
              will have their domain shrunk by the same amount.

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

       -bi[ncols][t] (more a|)
              Select native binary input. [Default is 3 input columns].

       -dinodata (more a|)
              Replace input columns that equal nodata with NaN.

       -e[~]^<i>apattern^<i>a | -e[~]/regexp/[i] (more a|)
              Only accept data records that match the given pattern.

       -f[i|o]colinfo (more a|)
              Specify data types of input and/or output columns.

       -h[i|o][n][+c][+d][+rremark][+rtitle] (more a|)
              Skip or produce header record(s).

       -^ 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.


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|)


GEOGRAPHICAL AND TIME COORDINATES

       When  the  output  grid type is netCDF, the coordinates will be labeled
       alongitudea, alatitudea, or atimea 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 -R90w/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  gmt.conf  file  or  on the command line. In addition, the unit
       attribute of the time variable will indicate both this unit and  epoch.


EXAMPLES

       Let  us  assume the file data.nc covers the area 300/310/10/30. We want
       to change the boundaries from geodetic longitudes to geographic and put
       a new title in the header. We accomplish this by

              gmt grdedit data.nc -R-60/-50/10/30 -D+t"Gravity Anomalies"

       The  grid  world.nc  has  the limits 0/360/-72/72. To shift the data so
       that the limits would be -180/180/-72/72, use

              gmt grdedit world.nc -R-180/180/-72/72 -S

       The file junk.nc was created prior to GMT 3.1 with incompatible -R  and
       -I arguments. To reset the x- and y-increments we run

              gmt grdedit junk.nc -A

       The  file  junk.nc  was created prior to GMT 4.1.3 and does not contain
       the required information to indicate that the grid  is  geographic.  To
       add this information, run

              gmt grdedit junk.nc -fg

       To  rotate  the  grid oblique.nc 90 degrees counter-clockwise and write
       out the rotated grid to a new file, run

              gmt grdedit oblique.nc -El -Goblique_rot.nc


SEE ALSO

       gmt(1), grd2xyz(1), grdinfo(1), xyz2grd(1)


COPYRIGHT

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



5.4.2                            Jun 24, 2017                       grdedit(1)

gmt5 5.4.2 - Generated Wed Jun 28 18:24:37 CDT 2017
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