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|
.. index:: ! grdvector
*********
grdvector
*********
.. only:: not man
grdvector - Plot vector field from two component grids
Synopsis
--------
.. include:: common_SYN_OPTs.rst_
**grdvector** *compx.nc* *compy.nc* **-J**\ *parameters* [ |-A| ]
[ |SYN_OPT-B| ]
[ |-C|\ *cpt* ]
[ |-G|\ *fill* ]
[ |-I|\ [**x**]\ *dx*\ [/*dy*] ]
[ |-K| ] [ |-N| ] [ |-O| ] [ |-P| ] [ |-Q|\ *parameters* ]
[ |SYN_OPT-R| ]
[ |-S|\ [**i**\ \|\ **l**\ ]\ *scale* ]
[ |-T| ]
[ |SYN_OPT-U| ]
[ |-W|\ *pen* ]
[ |SYN_OPT-X| ]
[ |SYN_OPT-Y| ]
[ |-Z| ]
[ |SYN_OPT-c| ]
[ |SYN_OPT-f| ]
[ |SYN_OPT-p| ]
[ |SYN_OPT-t| ]
|No-spaces|
Description
-----------
**grdvector** reads two 2-D grid files which represents the *x*\ - and
*y*\ -components of a vector field and produces a vector field plot by
drawing vectors with orientation and length according to the information
in the files. Alternatively, polar coordinate *r*, *theta* grids may be given
instead.
Required Arguments
------------------
*compx.nc*
Contains the x-components of the vector field.
*compy.nc*
Contains the y-components of the vector field. (See GRID FILE FORMATS below.)
.. _-J:
.. |Add_-J| unicode:: 0x20 .. just an invisible code
.. include:: explain_-J.rst_
Optional Arguments
------------------
.. _-A:
**-A**
The grid files contain polar (r, theta) components instead of
Cartesian (x, y) [Default is Cartesian components].
.. _-B:
.. include:: explain_-B.rst_
.. _-C:
**-C**\ [*cpt*]
Use *cpt* to assign colors based on vector length. Alternatively,
supply the name of a GMT color master dynamic CPT [rainbow] to
automatically determine a continuous CPT from
the grid's z-range. If the dynamic CPT has a default range then
that range will be imposed instead.
Yet another option is to specify -Ccolor1,color2[,color3,...]
to build a linear continuous cpt from those colors automatically.
In this case *color*\ **n** can be a r/g/b triplet, a color name,
or an HTML hexadecimal color (e.g. #aabbcc ).
.. _-G:
**-G**\ *fill*
Sets color or shade for vector interiors [Default is no fill].
.. _-I:
**-I**\ [**x**]\ *dx*\ [/*dy*]
Only plot vectors at nodes every *x\_inc*, *y\_inc* apart (must be
multiples of original grid spacing). Append **m** for arc minutes or
**s** for arc seconds. Alternatively, use **-Ix** to specify the
multiples *multx*\ [/*multy*] directly [Default plots every node].
.. _-K:
.. include:: explain_-K.rst_
.. _-N:
**-N**
Do NOT clip vectors at map boundaries [Default will clip].
.. _-O:
.. include:: explain_-O.rst_
.. _-P:
.. include:: explain_-P.rst_
.. _-Q:
**-Q**\ *parameters*
Modify vector parameters. For vector heads, append vector head
*size* [Default is 0, i.e., stick-plot]. See VECTOR ATTRIBUTES for
specifying additional attributes.
.. _-R:
.. |Add_-R| replace:: Specify a subset of the grid.
.. include:: explain_-R.rst_
.. _-S:
**-S**\ [**i**\ \|\ **l**\ ]\ *scale*
Sets scale for Cartesian vector length in data units per distance measurement
unit [1]. Append **c**, **i**, or **p** to indicate the measurement
unit (cm, inch,or point). Prepend **l** to indicate a fixed length
for all vectors. For Geographic data, give scale in data units per
km. Use **-Si** if it is simpler to give the reciprocal scale in
measurement unit per data unit or km per data unit.
.. _-T:
**-T**
Means the azimuths of Cartesian data sets should be adjusted according to the
signs of the scales in the x- and y-directions [Leave alone]. This option can
be used to convert vector azimuths in cases when a negative scale is used in
one of both directions (e.g., positive down).
.. _-U:
.. include:: explain_-U.rst_
.. _-V:
.. |Add_-V| unicode:: 0x20 .. just an invisible code
.. include:: explain_-V.rst_
.. _-W:
**-W**\ *pen*
Set pen attributes used for vector outlines [Default: width =
default, color = black, style = solid].
.. _-X:
.. include:: explain_-XY.rst_
.. _-Z:
**-Z**
The theta grid provided contains azimuths rather than directions (requires **-A**).
.. include:: explain_-c.rst_
.. |Add_-f| unicode:: 0x20 .. just an invisible code
.. include:: explain_-f.rst_
.. |Add_perspective| unicode:: 0x20 .. just an invisible code
.. include:: explain_perspective.rst_
.. include:: explain_-t.rst_
.. include:: explain_help.rst_
.. include:: explain_grd_inout_short.rst_
.. include:: explain_vectors.rst_
Examples
--------
To draw the vector field given by the files r.nc and theta.nc on a
linear plot with scale 5 cm per data unit, using vector rather than
stick plot, scale vector magnitudes so that 10 units equal 1 inch, and
center vectors on the node locations, run
::
gmt grdvector r.nc theta.nc -Jx5c -A -Q0.1i+e+jc -S10i > gradient.ps
To plot a geographic data sets given the files com_x.nc and comp_y.nc,
using a scale of 200 km per data unit and only plot every 3rd node in either direction, try
::
gmt grdvector comp_x.nc comp_y.nc -Ix3 -JH0/20c -Q0.1i+e+jc -S200 > globe.ps
See Also
--------
:doc:`gmt`, :doc:`gmtcolors`,
:doc:`grdcontour`, :doc:`psxy`
|
