I think you want to first copy the data, or else you may end up modifying the original Density data.<div><br></div><div>def _DensityCeiling(field, data):<br><div> Ceiling = 1e-22</div><div> new_dens = data["Density"].copy()</div>
<div> new_dens[new_dens > Ceiling] = Ceiling</div><div> return new_dens</div><div><br></div><div>Cheers,</div><div>Sam</div><div><br></div><div class="gmail_quote">On Thu, Oct 4, 2012 at 3:06 PM, Nathan Goldbaum <span dir="ltr"><<a href="mailto:nathan12343@gmail.com" target="_blank">nathan12343@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div>Hi Junhwan</div><div><br></div><div>In fact, in general you'll get back a 1D array. These are the collapsed values for the data in a single grid (i.e. flattened from 3D to 1D).</div>
<div><br></div><div>Since your field does not explicitly depend on the 3D nature of the grid, this is an easy fix:</div><div><br></div><div>def _DensityCeiling(field, data):</div><div><div bgcolor="#FFFFFF" text="#000000">
<font face="Monotype.com"> Ceiling = 1e-22</font></div><div bgcolor="#FFFFFF" text="#000000"><font face="Monotype.com"> wh = np.where(data["Density"] < Ceiling)<br> DensityCeiling = data["Density"]<br>
</font></div><div bgcolor="#FFFFFF" text="#000000"> DensityCeiling[wh] = Ceiling</div><div bgcolor="#FFFFFF" text="#000000"><font face="Monotype.com"> return DensityCeiling</font></div></div><div><br></div><div>Here np is how I've imported numpy locally. There may be an even cleverer way of doing the array manipulation that someone else on the list may know of off-hand.</div>
<div><br></div><div>Cheers,</div><div><br></div><div>Nathan</div><br><div><div><div><div>On Oct 4, 2012, at 2:00 PM, Jun-Hwan Choi wrote:</div><br></div></div><blockquote type="cite"><div><div>
<div bgcolor="#FFFFFF" text="#000000">
<font face="Monotype.com">Hi yt-users,<br>
<br>
I try to make a density projection of my simulation.<br>
I would like to make a small modification that if the cell density
higher than a given density ceiling the density value becomes the
density ceiling.<br>
And, I made a following script:<br>
############################################<br>
from yt.mods import *<br>
import matplotlib.pylab as pylab<br>
<br>
def _DensityCeiling(field, data):<br>
Ceiling = 1e-22<br>
nx, ny, nz = data["Density"].shape<br>
DensityCeiling = na.zeros(data["Density"].shape,
dtype='float64')<br>
DensityCeiling = data["Density"]<br>
for ix, in range(0,nx):<br>
for iy, in range(0,ny):<br>
for iz, in range(0,nz):<br>
if(data["DensityCeiling"][ix,iy,iz] >
Ceiling):<br>
DensityCeiling[ix,iy,iz] = Ceiling<br>
return DensityCeiling<br>
add_field("DensityCeiling", function=_DensityCeiling,
units=r"\rm{g}/\rm{cm^3}")<br>
<br>
<br>
# load up a dataset<br>
pf = load("DD0000/DD0000")<br>
all_center = [0.5, 0.5, 0.5]<br>
<br>
pc = PlotCollection(pf,center=all_center)<br>
pc.add_slice("DensityCeiling", 0)<br>
pc.add_slice("DensityCeiling", 2)<br>
pc.add_projection("DensityCeiling", 0)<br>
pc.add_projection("DensityCeiling", 2)<br>
<br>
pc.set_width(6, 'kpc')<br>
pc.save("cen_t%04.1f_L6K" % pf.current_time)<br>
pc.set_width(1, 'kpc')<br>
pc.save("cen_t%04.1f_L1K" % pf.current_time)<br>
#######################################################<br>
<br>
And then, I got a following error.<br>
File "DenViz.py", line 6, in _DensityCeiling<br>
nx, ny, nz = data["Density"].shape<br>
ValueError: need more than 1 value to unpack<br>
<br>
It turns out that the data</font><font face="Monotype.com">["Density"]
is not always 3d array but sometimes become 1d array.<br>
Is there any way to fix the derived field to avoid this problem?<br>
<br>
Thank you in advance,<br>
Junhwan<br>
</font><font face="Monotype.com"><br>
<br>
</font>
<pre cols="72">--
--------------------------------------------------------------
Jun-Hwan Choi, Ph.D.
Department of Physics and Astronomy, University of Kentucky
Tel: <a href="tel:%28859%29%20897-6737" value="+18598976737" target="_blank">(859) 897-6737</a> Fax: <a href="tel:%28859%29%20323-2846" value="+18593232846" target="_blank">(859) 323-2846</a>
Email: <a href="mailto:jhchoi@pa.uky.edu" target="_blank">jhchoi@pa.uky.edu</a> URL: <a href="http://www.pa.uky.edu/~jhchoi" target="_blank">http://www.pa.uky.edu/~jhchoi</a>
--------------------------------------------------------------
</pre>
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