[GRASS-user] How to plot arrows style of speed and direction of wind...

[Moritz Lennert]

On 23/06/11 16:03, sgw00412 at nifty.com wrote:
> Dear grass user
> 
> Recently, I am feeling sorry for many questions....
> 
> I'm looking for how to plot arrows of speed and direction of wind.
> for example, if station A has 4m/s and Eest (degree 90 )of annual average wind
>   situation,
> the plot like arrow style;
> <----xA
> Other hand, if station B has 2m/s and West (degree 270 ) of annal average wind
>   situation,
> the plot also like arrow style:
> Bx-->
> ...and so on.
> 
> In this case, data set is as follows;
> 
> station | lat | lon | w.speed | w.direction |
> tokyo   | 35.2| 25.4| 4.0     | 90          |
> osaka   | 24.5| 33.9| 2.0     | 270         |
> ...
> 
> w.speed is single and w.direction is integer. Wind direciotn ranges between 1
> (=north), 90 (=east), 180 (=south), 270 (=west) and 360 (=north).
> 
> I think that this data set can import to vector data by using v.in.ascii...
> So, I'm looking for command -- d.vect --, but can not find to arrows style of
> speed and direction of wind...I think that it is difficult to show an arrow st
> yle by using two properties (=two columns, speed and direction )....

You can use rot_column to define rotation and size_colum to define size
depending on speed. But this is size, not length...

Use icon= for defining a symbol (see [1] for examples).

But you might be better off using a raster approach and d.rast.arrow.
See example at [2].

Or check out Hamish' d.barb AddOn module [3].

Moritz

[1] http://grass.osgeo.org/wiki/IconSymbols
[2] http://grass.osgeo.org/wiki/Meteorology
[3] http://grass.osgeo.org/wiki/GRASS_AddOns#d.barb