Provided by: gmt_4.5.11-1build1_amd64 bug


       grdedit - Modifying the header or content of a 2-D grid file


       grdedit  grdfile  [  -A  ]  [  -Dxname/yname/zname/scale/offset/title/remark  ]  [  -E ] [
       -Nxyzfile ] [ -Rwest/east/south/north[r] ]  [  -S  ]  [  -T  ]  [  -V  ]  [  -:[i|o]  ]  [
       -bi[s|S|d|D[ncol]|c[var1/...]] ] [ -f[i|o]colinfo ]


       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  longitude 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 grdheader.

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


       No space between the option flag and the associated arguments.

       -A     If necessary, adjust the file's 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.

       -D     Give new values for xname, yname, zname, scale,  offset,  title,  and  remark.   To
              leave  some of the values untouched, specify = as the new value.  Alternatively, to
              allow "/" to be part of one of the values, use any non-alphanumeric character  (and
              not  the equal sign) as separator by both starting and ending with it. For example:

       -E     Transpose the grid and exchange the x and y  information.   Incompatible  with  the
              other options.

       -H     Input  file(s) has header record(s).  If used, the default number of header records
              is N_HEADER_RECS.  Use -Hi if only input data should have header  records  [Default
              will  write  out header records if the input data have them]. Blank lines and lines
              starting with # are always skipped.

       -N     Read the ASCII (or binary; see -bi) file  xyzfile  and  replace  the  corresponding
              nodal values in the grid with these z values.

       -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[][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).  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-registered  grid  to  a
              pixel-registered  grid,  or  vice-versa.  Basically, 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     Selects  verbose  mode,  which  will  send progress reports to stderr [Default runs

       -bi    Selects binary input.  Append s for  single  precision  [Default  is  d  (double)].
              Uppercase  S or D will force byte-swapping.  Optionally, append ncol, the number of
              columns in your binary input file if it exceeds the columns needed by the  program.
              Or  append  c  if  the  input  file  is netCDF. Optionally, append var1/var2/... to
              specify the variables to be read.  [Default is 3 input columns].

       -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).


       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.


       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.


       Let us assume the file data.grd 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

       grdedit data.grd -R-60/-50/10/30 -D=/=/=/=/=/"Gravity Anomalies"/=

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

       grdedit world.grd -R-180/180/-72/72 -S

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

       grdedit junk.grd -A

       The file junk.grd 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

       grdedit junk.grd -fg


       GMT(1), grd2xyz(1), xyz2grd(1)