Re: [Anuga-user] FW: Changing Elevation to a Set Value

[Ole N. <ole...@gm...>]

You should be able to call set_quantity with a polygon restricting where
values are changed. That could be used to reset parts of the domain.
Something like

domain.set_quantity(0, polygon=......)

To see what is possible, consult the underlying function set_values
(everything you pass to set_quantity is passed down to set_values in the
quantity object):

http://datamining.anu.edu.au/browser/trunk/anuga_core/source/anuga/abstract_2d_finite_volumes/quantity.py#L344


An excerpt from the docstring states:

Restrict update of quantity to locations that fall inside polygon. Polygon
works by selecting indice  and calling set_values recursively.  Polygon mode
has only been implemented for constant values so far.

Let me know how it goes
O


On Tue, Apr 12, 2011 at 11:26 AM, Ole Nielsen <ole...@ai...> wrote:

>
>
> -----Original Message-----
> From: Rudy [mailto:ru...@ba...]
> Sent: Monday, 11 April 2011 8:55 PM
> To: Ole Nielsen
> Subject: Re: Changing Elevation to a Set Value
>
> Hi Ole,
>
>
> Yes I tried using add_quantity....
>
> the problem is if I want to define something new in place of the existing
> terrain, I need to start from Zero!
>
> I have not been able to subtract a portion of the existing terrain (inside
> a polygon) from the existing terrain, to set it to zero, and then to add
> the new replacement terrain, like an embankment !!
>
>
> I think I need to use the get_values restricted to a polygon.... and then
> set_values for the same polygon...
>
> So Q1 = get_values (polygon)
>    Q2 = -Q1
>    Q3 = set_values(polygon, new terrain)
>
> New elevation = Q1+Q2+Q3    ( = 0 +new terrain) ???
>
> Trying to use add_quantity, to a variable underlying terrain is very
> clumsy and time consuming, and does not provide a good result.... (unless
> I am doing it wrong?)
>
>
> ANy clues or ideas ??
>
> Regards Rudy
>
>
>
> On Mon, 11 Apr 2011 20:09:00 +1000, Ole Nielsen <ole...@ai...>
> wrote:
>
> > You can just use add_quantity() and built it up piece by piece.
> > O
> >
> >
> >
> > -----Original Message-----
> > From: Rudy [mailto:ru...@ba...]
> > Sent: Monday, 11 April 2011 12:45 PM
> > To: Ole Nielsen; Jan...@ga...; Stephen Roberts
> > Cc: 'Nar...@ga...'
> > Subject: Re: Changing Elevation to a Set Value
> >
> > I note that in quantity.py  it states the following:
> >
> >
> >          # FIXME (Ole): I reckon we should have the option of passing a
> >          #              polygon into get_values. The question becomes how
> >          #              resulting values should be ordered.
> >
> >
> >
> >
> > and for set.values
> >
> >
> >          polygon: Restrict update of quantity to locations that fall
> >                   inside polygon. Polygon works by selecting indices
> >                   and calling set_values recursively.
> >                   Polygon mode has only been implemented for
> >                   constant values so far.
> >
> > So does that mean it is not possible to use existing tools to set the
> > elevation values within a polygon to ZERO ??
> >
> > I would have thought that you need to get.values for the polygon    and
> > then set.values.
> >
> >
> > I want to create a Flat area of Zero, so that I can then adjust the
> > elevation by adding to it ??
> >
> >
> > Any one done this before ?
> >
> >
> > Regards rudy
>
>
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