Ubuntu Manpage: grdinfo - Extract information from grids

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

NAME

       grdinfo - Extract information from grids

SYNOPSIS

       grdinfo  grdfiles  [   ]  [   ]  [  [dx[/dy]|r|b]  ]  [ [0|1|2] ] [  ] [ region ] [ [s]dz ] [ [level] ] [
       -f<flags> ]

       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, L1 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).

       -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]|r|b]
              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.  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]

              -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.

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

       -R[unit]xmin/xmax/ymin/ymax[r] (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.

       -Tdz   Determine min and max z-value, round off to multiples  of  dz,  and  report  as  the  text  string
              -Tzmin/zmax/dz  for  use by makecpt. To get a symmetrical range about zero, using the max absolute
              multiple of dz, use -Tsdz instead.

       -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 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.

EXAMPLES

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

              gmt grdinfo -L1 -L2 -M hawaii_topo.nc

COPYRIGHT

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

5.2.1                                           January 28, 2016                                   GRDINFO(1gmt)