.. index:: ! grdinfo

*******
grdinfo
*******

.. only:: not man

    grdinfo - Extract information from grids

Synopsis
--------

.. include:: common_SYN_OPTs.rst_

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

|No-spaces|

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:

**-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:

**-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:

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

.. _-I:

**-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 **-R**\ *w/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
    **-I**\ *xinc/yinc*. If **-Ib** is given we write each grid's
    bounding box polygon instead.

.. _-L:

**-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:

**-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:

.. |Add_-R| replace:: 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.
.. include:: explain_-R.rst_

.. _-T:

|-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 **-T**\ *zmin/zmax* or **-T**\ *zmin/zmax/dz*
    (if *dz* was given) as expected by :doc:`makecpt`.

.. _-V:

.. |Add_-V| unicode:: 0x20 .. just an invisible code
.. include:: explain_-V.rst_

.. |Add_-f| unicode:: 0x20 .. just an invisible code
.. include:: explain_-f.rst_

.. include:: explain_help.rst_

.. include:: explain_grd_inout_short.rst_

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
--------

:doc:`gmt`, :doc:`grd2cpt`,
:doc:`grd2xyz`, :doc:`grdedit`