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grdinfo(1)                            GMT                           grdinfo(1)




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 infor-
       mation 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  FOR-
              MATS 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  gridas  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 gridas 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 a|)
              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 a|)
              Select verbosity level [c].

       -f[i|o]colinfo (more a|)
              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  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|)


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(1), grd2cpt(1), grd2xyz(1), grdedit(1)


COPYRIGHT

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



5.4.2                            Jun 24, 2017                       grdinfo(1)

gmt5 5.4.2 - Generated Wed Jun 28 20:20:12 CDT 2017
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