NAME

       grdinfo - Extract information from grids

SYNOPSIS

       grdinfo  grdfiles  [   -C  ]  [   -D[xoff[/yoff][+n]  ]  [   -F ] [  -I[dx[/dy]|b|i|r] ] [
       -L[0|1|2|p|a] ] [  -M ] [  -Rregion ] [  -T[dz][+a[alpha]][+s] ] [  -V[level] ] [  -fflags
       ]

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

DESCRIPTION

       grdinfo  reads  a 2-D binary grid file and reports metadata and various statistics for the
       (x,y,z) data in the grid file(s).  The output  information  contains  the  minimum/maximum
       values  for  x,  y,  and z, where the min/max of z occur, the x- and y-increments, and the
       number of x and y nodes, and [optionally] the mean, standard deviation, and/or the median,
       median absolute deviation of z, and/or the mode (LMS), LMS scale of z, and number of nodes
       set to NaN. We also report if the grid is pixel- or gridline-registered and  if  it  is  a
       Cartesian or Geographic data set (based on metadata in the file).

REQUIRED ARGUMENTS

       grdfile
              The name of one or several 2-D grid files. (See GRID FILE FORMATS below.)

OPTIONAL ARGUMENTS

       -C     Formats the report using tab-separated fields on a single line. The output is w e s
              n z0 z1 dx dy nx ny[ x0 y0 x1 y1 ] [ med scale ] [mean std rms] [n_nan].  The  data
              in  brackets  are output only if the corresponding options -M, -L1, -L2, and -M are
              used, respectively. If the -I option is used, the output format is instead NF w e s
              n  z0  z1,  where  NF is the total number of grids read and w e s n are rounded off
              (see -I).

       -D[xoff[/yoff][+i]
              Divide a single grid's domain (or the -R domain, if no grid given)  into  tiles  of
              size  dx times dy (set via -I).  You can specify overlap between tiles by appending
              xoff[/yoff].  If the single grid is given you may use the  modifier  +i  to  ignore
              tiles that have no data within each tile subregion.

       -F     Report grid domain and x/y-increments in world mapping format [Default is generic].
              Does not apply to the -C option.

       -I[dx[/dy]|b|i|r]
              Report the min/max of the region to the nearest multiple of dx and dy,  and  output
              this  in  the  form -Rw/e/s/n (unless -C is set). To report the actual grid region,
              select -Ir. For a grid produced by the img supplement (a Cartesian Mercator  grid),
              the  exact  geographic  region  is  given with -Ii (if not found then we return the
              actual grid region instead).  If no argument is  given  then  we  report  the  grid
              increment  in  the  form -Ixinc/yinc. If -Ib is given we write each grid's bounding
              box polygon instead.

       -L[0|1|2|p|a]

              -L0    Report range of z after actually scanning the data, not just reporting  what
                     the header says.

              -L1    Report  median  and  L1  scale  of  z  (L1  scale = 1.4826 * Median Absolute
                     Deviation (MAD)).

              -L2    Report mean, standard deviation, and root-mean-square (rms) of z.

              -Lp    Report mode (LMS) and LMS scale of z.

              -La    All of the above.

              Note: If the grid is geographic then each node  represents  a  physical  area  that
              decreases  with  increasing  latitude.   We  therefore  report spherically weighted
              statistical estimates for such grids.

       -M     Find and report the location of min/max z-values, and count and report  the  number
              of nodes set to NaN, if any.

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

        -T[dz][+a[alpha]][+s]
              Determine  min and max z-value.  If dz is provided then we first round these values
              off to multiples of  dz.  To  exclude  the  two  tails  of  the  distribution  when
              determining the min and max you can add +a to set the alpha value (in percent [2]):
              We then sort the grid, exclude the data in the 0.5*alpha and 100 - 0.5*alpha tails,
              and  revise  the  min  and  max.   To  force  a symmetrical range about zero, using
              minus/plus the max absolute value of the two extremes, append  +s.  We  report  the
              result  via  the  text  string  -Tzmin/zmax  or -Tzmin/zmax/dz (if dz was given) as
              expected by makecpt.

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

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

       -^ 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  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  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 "packing" of grids, writing out floating point
       data as 1- or 2-byte integers. (more ...)

EXAMPLES

       To obtain all the information about the data set in file hawaii_topo.nc:

              gmt grdinfo -L1 -L2 -M hawaii_topo.nc

SEE ALSO

       gmt, grd2cpt, grd2xyz, grdedit

COPYRIGHT

       2019, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe