.. index:: ! gmtinfo

*******
gmtinfo
*******

.. only:: not man

    gmtinfo - Get information about data tables

Synopsis
--------

.. include:: common_SYN_OPTs.rst_

**gmtinfo** [ *table* ] [ |-A|\ **a**\ \|\ **f**\ \|\ **s** ]
[ |-C| ]
[ |-D|\ [*dx*\ [/*dy*\ ]] ]
[ |-E|\ **L**\ \|\ **l**\ \|\ **H**\ \|\ **h**\ *col* ]
[ |-F|\ [**i**\ \|\ **d**\ \|\ **t**\ ] ]
[ |-I|\ [**p**\ \|\ **f**\ \|\ **s**]\ *dx*\ [/*dy*\ [/*dz*...] ]
[ |-L| ]
[ |-S|\ [**x**\ ][**y**] ]
[ |-T|\ *dz*\ [\ **+c**\ *col*] ]
[ |SYN_OPT-V| ]
[ |SYN_OPT-bi| ]
[ |SYN_OPT-di| ]
[ |SYN_OPT-e| ]
[ |SYN_OPT-f| ]
[ |SYN_OPT-g| ]
[ |SYN_OPT-h| ]
[ |SYN_OPT-i| ]
[ |SYN_OPT-o| ]
[ **-r** ]
[ |SYN_OPT-:| ]

|No-spaces|

Description
-----------

**gmtinfo** reads its standard input [or from files] and finds the
extreme values in each of the columns reported as slash-separated min/max
pairs. It recognizes NaNs and will print warnings if the number of columns
vary from record to record. The pairs can be split into two separate columns
by using the **-C** option.  As another option, **gmtinfo** can find the extent
of data in the first two columns rounded up and down to the nearest multiple of the
supplied increments given by **-I**. Such output will be in the text form
**-R**\ *w/e/s/n*, which can be used directly on the command line for other
modules (hence only *dx* and *dy* are needed).  If **-C** is combined with
**-I** then the output will be in column form and rounded up/down for as many
columns as there are increments provided in **-I**. A similar option (**-T**)
will provide a **-T**\ *zmin/zmax/dz* string for makecpt.

Required Arguments
------------------

None.

Optional Arguments
------------------

.. |Add_intables| unicode:: 0x20 .. just an invisible code
.. include:: explain_intables.rst_

.. _-A:

**-A**\ **a**\ \|\ **f**\ \|\ **s**
    Specify how the range should be reported. Choose **-Aa** for the
    range of all files combined, **-Af** to report the range for each
    file separately, and **-As** to report the range for each segment
    (in multisegment files) separately. [Default is **-Aa**].

.. _-C:

**-C**
    Report the min/max values per column in separate columns [Default
    uses <min/max> format]. When used, users may also use **-o** to
    limit which output columns should be reported [all].

.. _-D:

**-D**
    Modifies results obtained by **-I** by shifting the region to better
    align with the center of the data.  Optionally, append granularity
    for this shift [Default performs an exact shift].

.. _-E:

**-EL**\ \|\ **l**\ \|\ **H**\ \|\ **h**\ *col*
    Returns the record whose column *col* contains the minimum
    (**l**) or maximum (**h**) value. Upper case
    (**L\|H**) works on absolute value of the data. In case of multiple
    matches, only the first record is returned. If *col* is not
    specified we default to the last column in the data.

.. _-F:

**-F**\ [**i**\ \|\ **d**\ \|\ **t**\ ] ]
    Returns the counts of various records depending on the appended mode:
    **i** returns a single record with the total number of tables, segments,
    data records, header records, and overall records.  In contrast, **d** returns
    information for each segment in the virtual data set: *tbl_number, seg_number,
    n_rows, start_rec, stop_rec*. **t** does the same but honors the input
    table organization and thus resets *seg_number, start_rec, stop_rec* at the
    start of each new table.

.. _-I:

**-I**\ [**p**\ \|\ **f**\ \|\ **s**]\ *dx*\ [/*dy*\ [/*dz*...]
    Report the min/max of the first *n* columns to the nearest multiple
    of the provided increments (separate the *n* increments by slashes),
    and output results in the form **-R**\ *w/e/s/n* (unless **-C** is
    set). If only one increment is given we also use it for the second
    column (for backwards compatibility). To override this behavior, use
    **-Ip**\ *dx*. If the input *x*- and *y*-coordinates all have the
    same phase shift relative to the *dx* and *dy* increments then we
    use those phase shifts in determining the region, and you may use
    **-r** to switch from gridline-registration to pixel-registration.
    For irregular data both phase shifts are set to 0 and the **-r** is ignored.
    Use **-If**\ *dx*\ [/*dy*] to report an extended region optimized
    to give grid dimensions for fastest results in programs using FFTs.
    Use **-Is**\ *dx*\ [/*dy*] to report an extended region optimized to
    give grid dimensions for fastest results in programs like surface.
    If *dx* is given as - then the actual min/max of the input is given in the **-R** string.

.. _-L:

**-L**
    Determines common limits across tables (**-Af**) or segments (**-As**).
    If used with **-I** it will round inwards so that the resulting bounds
    lie within the actual data domain.

.. _-S:

**-S**\ [**x**][**y**]
    Add extra space for error bars. Useful together with **-I** option
    and when later plotting with :doc:`psxy` **-E**. **-Sx** leaves space
    for horizontal error bars using the values in third
    (2) column. **-Sy** leaves space for vertical error
    bars using the values in fourth (3) column. **-S**
    or **-Sxy** leaves space for both error bars using the values in
    third and fourth (2 and 3) columns.

.. _-T:

**-T**\ *dz*\ [\ **+c**\ *col*]
    Report the min/max of the first (0'th) column to the nearest multiple of *dz* and output this as the
    string **-T**\ *zmin/zmax/dz*. To use another column, append **+c**\ *col*. Cannot be used together with **-I**.

.. _-V:

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

.. |Add_-bi| replace:: [Default is 2 input columns].
.. include:: explain_-bi.rst_

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

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

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

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

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

.. include:: explain_-icols.rst_

.. include:: explain_-ocols.rst_

.. |Add_nodereg| unicode:: 0x20 .. just an invisible code
.. include:: explain_nodereg.rst_

.. include:: explain_colon.rst_

.. include:: explain_help.rst_

.. include:: explain_precision.rst_

Examples
--------

To find the extreme values in the file ship\_gravity.xygd:

  ::

    gmt info ship_gravity.xygd

Output should look like

  ::

    ship_gravity.xygd: N = 6992 <326.125/334.684> <-28.0711/-8.6837> <-47.7/177.6> <0.6/3544.9>

To find the extreme values in the file track.xy to the nearest 5 units
but shifted to within 1 unit of the data center, and use this region to
draw a line using :doc:`psxy`, run

  ::

    gmt psxy `gmt info -I5 -D1 track.xy` track.xy -Jx1 -B5 -P > track.ps

To find the min and max values for each of the first 4 columns, but
rounded to integers, and return the result individually for each data
file, use

  ::

    gmt info profile_*.txt -C -I1/1/1/1

Given seven profiles with different start and stop positions, we
want to find a range of positions, with increment of 5, that are
common to all the profiles.  We use

  ::

    gmt info profile_[123567].txt -L -I5

The file magprofs.txt contains a number of magnetic profiles stored
as separate data segments.  We need to know how many segments there
are and use

  ::

    gmt info magprofs.txt -Fi

Bugs
----

The **-I** option does not yet work properly with time series data
(e.g., **-f**\ 0T). Thus, such variable intervals as months and years
are not calculated. Instead, specify your interval in the same units as
the current setting of :ref:`TIME_UNIT <TIME_UNIT>`.

See Also
--------

:doc:`gmt`,
:doc:`gmtconvert`,
:doc:`psxy`

