xenial (1) grdedit.1gmt.gz

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

NAME

       grdedit - Modify header or content of a grid

SYNOPSIS

       grdedit grid [  ] [ xname/yname/zname/scale/offset/invalid/title/remark ] [ [a|h|l|r|t|v] ] [ outgrid ] [
       parameters ] [ table ] [ region ] [  ] [  ] [ [level] ] [ -bi<binary> ] [ -di<nodata> ] [ -f<flags>  ]  [
       -i<flags> ] [ -:[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
       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 grid header. Note: If  it  is
       important 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 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.

       -Dxname/yname/zname/scale/offset/invalid/title/remark
              Give values for xname, yname, zname (give the names of those variables and in square bracket their
              units, e.g., "distance [km]"), 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). To leave  some  of  these  values  untouched,
              leave  field blank. Empty fields in the end may be skipped. 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:
              -D:xname:yname:zname:scale:offset:invalid:title:remark: 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) interchange 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 modified grid.  Use -G to write the
              modified grid to the file outgrid instead.

       -Jparameters (more ...)
              Select map projection. Use the -J syntax  to  save  the  georeferencing  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.

       -R[unit]xmin/xmax/ymin/ymax[r] (more ...)
              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-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[level] (more ...)
              Select verbosity level [c].

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

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

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

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

       -icols[l][sscale][ooffset][,...] (more ...)
              Select input columns (0 is first column).

       -^ 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.

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 -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//////"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, grd2xyz, grdinfo xyz2grd

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