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

       2018, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe

5.4.3                                             Jan 03, 2018                                     GRDINFO(1gmt)