[AstroPy] AstroPy Digest, Vol 63, Issue 4

Jean-Baptiste Marquette marquett@iap...
Tue Nov 8 07:56:38 CST 2011


Dear all,

Thanks to all for your suggestions, it seems that np.histogram2d fits my needs.
I am currently finishing the script.

Cheers
JB


Le 7 nov. 2011 à 21:52, Eli Bressert a écrit :

> Dear Jean Baptiste,
> 
> I have written up a script to do exactly what you have requested. This code is not fine-tuned for sharing, but you're free to use it. Also, the code is optimized for Galactic plane images. I have not tried using it for high declination images. Hope you find it useful. 
> 
> http://dl.dropbox.com/u/1356410/fits_creator.py
> 
> Cheers,
> Eli
> 
> 
> 
> On Monday, 7 November 2011 at 19:00, astropy-request@scipy.org wrote:
> 
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>> Today's Topics:
>> 
>> 1. A question about contour maps (Jean-Baptiste Marquette)
>> 2. Re: A question about contour maps (Wolfgang Kerzendorf)
>> 3. Re: A question about contour maps (Michael S. Kelley)
>> 4. Re: A question about contour maps (Miguel de Val-Borro)
>> 
>> 
>> ----------------------------------------------------------------------
>> 
>> Message: 1
>> Date: Mon, 7 Nov 2011 15:58:47 +0100
>> From: Jean-Baptiste Marquette <marquett@iap.fr (mailto:marquett@iap.fr)>
>> Subject: [AstroPy] A question about contour maps
>> To: astropy@scipy.org (mailto:astropy@scipy.org)
>> Message-ID: <8829B407-25F3-4E64-98E9-8D55D070C206@iap.fr (mailto:8829B407-25F3-4E64-98E9-8D55D070C206@iap.fr)>
>> Content-Type: text/plain; charset=us-ascii
>> 
>> Dear AstroPy people,
>> 
>> I have an ASCII table with RA/DEC coordinates and the values of a given parameter at those positions. I would like to plot a contour map of this parameter on an image with RA/DEC coordinates. I was able create a blank image using pyfits. I guess I could use the APLpy FITSFigure.show_contour method if my data were organized as a FITS file.
>> How to export from ASCII to FITS?
>> 
>> Thanks for your help,
>> Jean-Baptiste Marquette
>> 
>> ------------------------------
>> 
>> Message: 2
>> Date: Mon, 7 Nov 2011 10:26:37 -0500
>> From: Wolfgang Kerzendorf <wkerzendorf@googlemail.com (mailto:wkerzendorf@googlemail.com)>
>> Subject: Re: [AstroPy] A question about contour maps
>> To: Jean-Baptiste Marquette <marquett@iap.fr (mailto:marquett@iap.fr)>
>> Cc: astropy@scipy.org (mailto:astropy@scipy.org)
>> Message-ID: <E6A7A3C0-CBC6-4B8E-8FA2-CBB29A501F89@gmail.com (mailto:E6A7A3C0-CBC6-4B8E-8FA2-CBB29A501F89@gmail.com)>
>> Content-Type: text/plain; charset=us-ascii
>> 
>> Hi Jean-Baptiste,
>> 
>> So I figure you do not want to plot points at each location of the points specified in your ASCII table? I think APLPy works with pixel coordinates internally and just overplots a wcs grid. You can convert these points with wcstools xy2sky (It also works with pywcs, but for some projections there's something off) to pixel coordinates and then use histogram2d to make a 2d density array. Finally, you use contour to plot it over your aplply plot. I don't know of any easier way for now. May Thomas knows more.
>> 
>> Cheers
>> Wolfgang
>> On 2011-11-07, at 9:58 AM, Jean-Baptiste Marquette wrote:
>> 
>>> Dear AstroPy people,
>>> 
>>> I have an ASCII table with RA/DEC coordinates and the values of a given parameter at those positions. I would like to plot a contour map of this parameter on an image with RA/DEC coordinates. I was able create a blank image using pyfits. I guess I could use the APLpy FITSFigure.show_contour method if my data were organized as a FITS file.
>>> How to export from ASCII to FITS?
>>> 
>>> Thanks for your help,
>>> Jean-Baptiste Marquette
>>> _______________________________________________
>>> AstroPy mailing list
>>> AstroPy@scipy.org (mailto:AstroPy@scipy.org)
>>> http://mail.scipy.org/mailman/listinfo/astropy
>> 
>> 
>> 
>> 
>> 
>> ------------------------------
>> 
>> Message: 3
>> Date: Mon, 7 Nov 2011 10:28:23 -0500
>> From: "Michael S. Kelley" <msk@astro.umd.edu (mailto:msk@astro.umd.edu)>
>> Subject: Re: [AstroPy] A question about contour maps
>> To: Jean-Baptiste Marquette <marquett@iap.fr (mailto:marquett@iap.fr)>
>> Cc: astropy@scipy.org (mailto:astropy@scipy.org)
>> Message-ID:
>> <CAAwW0FAp+89PfkOqYZDp=CSN=WfdmepRoRThMzYMn6idT8h0Xw@mail.gmail.com (mailto:WfdmepRoRThMzYMn6idT8h0Xw@mail.gmail.com)>
>> Content-Type: text/plain; charset=ISO-8859-1
>> 
>> Hi Jean-Baptiste,
>> 
>> I'm not sure what kind of projection you are interested in, but, at
>> the most basic level, you can do a weighted 2D histogram on your data
>> list. For example:
>> 
>> import numpy as np
>> import matplotlib.pyplot as mpl
>> ra = np.random.randn(1000)
>> dec = np.random.randn(1000) + 10
>> w = np.random.randn(1000)**2
>> h = np.histogram2d(dec, ra, bins=100, weights=w)
>> mpl.clf()
>> mpl.imshow(h[0], extent=np.r_[h[2][[0, -1]], h[1][[0, -1]]], cmap=mpl.cm.gray_r)
>> mpl.plot(ra, dec, 'rx')
>> mpl.draw()
>> 
>> - Mike Kelley
>> 
>> On Mon, Nov 7, 2011 at 9:58 AM, Jean-Baptiste Marquette <marquett@iap.fr (mailto:marquett@iap.fr)> wrote:
>>> Dear AstroPy people,
>>> 
>>> I have an ASCII table with RA/DEC coordinates and the values of a given parameter at those positions. I would like to plot a contour map of this parameter on an image with RA/DEC coordinates. I was able create a blank image using pyfits. I guess I could use the APLpy FITSFigure.show_contour method if my data were organized as a FITS file.
>>> How to export from ASCII to FITS?
>>> 
>>> Thanks for your help,
>>> Jean-Baptiste Marquette
>>> _______________________________________________
>>> AstroPy mailing list
>>> AstroPy@scipy.org (mailto:AstroPy@scipy.org)
>>> http://mail.scipy.org/mailman/listinfo/astropy
>> 
>> 
>> 
>> 
>> 
>> -- 
>> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
>> Michael S Kelley
>> Department of Astronomy
>> University of Maryland -- College Park
>> 301-405-3796
>> 
>> 
>> ------------------------------
>> 
>> Message: 4
>> Date: Mon, 7 Nov 2011 16:31:02 +0100
>> From: Miguel de Val-Borro <miguel.deval@gmail.com (mailto:miguel.deval@gmail.com)>
>> Subject: Re: [AstroPy] A question about contour maps
>> To: Jean-Baptiste Marquette <marquett@iap.fr (mailto:marquett@iap.fr)>
>> Cc: astropy@scipy.org (mailto:astropy@scipy.org)
>> Message-ID: <20111107153102.GA28133@poincare.pc.linmpi.mpg.de (mailto:20111107153102.GA28133@poincare.pc.linmpi.mpg.de)>
>> Content-Type: text/plain; charset=utf-8
>> 
>> Dear Jean-Baptiste,
>> 
>> If the data is in ASCII format you could use numpy.loadtxt to load the
>> data into numpy arrays and use directly the matplotlib.pyplot.contourf
>> function to make a contour plot. The first example in this cookbook
>> shows how to make a contour plot from irregularly spaced data using the
>> scipy.interpolate.griddata function for interpolation onto a uniform
>> grid:
>> http://www.scipy.org/Cookbook/Matplotlib/Gridding_irregularly_spaced_data
>> 
>> Regards,
>> Miguel
>> 
>> On Mon, Nov 07, 2011 at 03:58:47PM +0100, Jean-Baptiste Marquette wrote:
>>> Dear AstroPy people,
>>> 
>>> I have an ASCII table with RA/DEC coordinates and the values of a given parameter at those positions. I would like to plot a contour map of this parameter on an image with RA/DEC coordinates. I was able create a blank image using pyfits. I guess I could use the APLpy FITSFigure.show_contour method if my data were organized as a FITS file.
>>> How to export from ASCII to FITS?
>>> 
>>> Thanks for your help,
>>> Jean-Baptiste Marquette
>>> _______________________________________________
>>> AstroPy mailing list
>>> AstroPy@scipy.org (mailto:AstroPy@scipy.org)
>>> http://mail.scipy.org/mailman/listinfo/astropy
>> 
>> 
>> 
>> 
>> ------------------------------
>> 
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>> 
>> End of AstroPy Digest, Vol 63, Issue 4
>> **************************************
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