Mailman 3 আগস্ট 2010 - AstroPy

Problem running pywcs example
by Peter Erwin 21 আগস্ট, 2010

21 আগস্ট, 2010

Hi, I decided to check out pywcs (in part because using Pyraf to get pixel values from RA,Dec pairs seemed to be overkill, and wcwcstran was failing to work for SDSS images with declinations close to zero). The installation ("python setup.py install") seemd to go fine, but I ran into the following when I tried running the example from http://stsdas.stsci.edu/astrolib/pywcs/examples.html <<begin quote>> In [164]: hdulist = pyfits.open("pgc1905g_94-220.fits") # this is an SDSS g-band image In [165]: wcs = pywcs.WCS(hdulist[0].header) --------------------------------------------------------------------------- AttributeError Traceback (most recent call last) /Users/erwin/Documents/Working/ESO_observing/WFI/targets/pgc1905_808/<ipython console> in <module>() /Users/erwin/lib/python/pywcs/pywcs.py in __init__(self, header, fobj, key, minerr, relax, naxis) 176 self.naxis = wcsprm.naxis 177 --> 178 det2im = self._read_det2im_kw(header, fobj) 179 cpdis = self._read_distortion_kw( 180 header, fobj, key=key,dist='CPDIS', err=minerr) /Users/erwin/lib/python/pywcs/pywcs.py in _read_det2im_kw(self, header, fobj) 278 cdelt = [1.,1.] 279 --> 280 if not isinstance(fobj, pyfits.NP_pyfits.HDUList): 281 return (None, None) 282 AttributeError: 'module' object has no attribute 'NP_pyfits' <<end quote>> My system is: MacBook Pro (2009) running Mac OS 10.6.4, Python 2.6.5 (standard framework install from python.org) via ipython 0.10 numpy 1.4.1 pyfits 2.3.1 [same problem occurred for pyfits 2.2.2; I pywcs v1.9-4.4.4 (All packages are installed inside the framework directory, *except* for pyfits, which installed in ~/lib/python ) Any suggestions? -- Peter ============================================================= Peter Erwin Max-Planck-Insitute for Extraterrestrial erwin(a)mpe.mpg.de Physics, Giessenbachstrasse tel. +49 (0)89 30000 3695 85748 Garching, Germany fax +49 (0)89 30000 3495 http://www.mpe.mpg.de/~erwin

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IDLSave 0.9.7 released
by Thomas Robitaille 18 আগস্ট, 2010

18 আগস্ট, 2010

I am happy to announce the availability of IDLSave 0.9.7. IDLSave is a pure Python module to import variables from IDL ‘save’ files into Python, and does not require IDL to work. I am also happy to announce that the IDLSave code has now also been included in scipy.io (thanks to Matthew Brett). The idlsave.read function is available via scipy.io.readsav and/or scipy.io.idl.readsav. Most of the changes in 0.9.6 and 0.9.7 are related to the move to scipy. In particular, unit tests are now present, and several small bugs uncovered in the process have been fixed. For the foreseeable future, IDLSave will be maintained in parallel with the scipy.io version, so there is no obligation to change to the scipy.io version at this stage. More information and download/installation instructions are available at http://idlsave.sourceforge.net/ Please let me know if you encounter any problems, or have any suggestions, Best regards, Thomas Robitaille

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Databases and Python
by Kelle Cruz 13 আগস্ট, 2010

13 আগস্ট, 2010

Hey Guys, There's a question on the AstroBetter Facebook Discussion board about databases and SQL in Python: "i am looking for a tool to easily build databases - which would change/track changes and be SQL searchable....anyone with experience with SQLalchemy?" http://www.facebook.com/pages/AstroBetter/220025848560?v=app_2373072738#!/t… i prefer you respond on the FB page...or take up the conversation on AstroPython. but do what you will. kelle -- Kelle Cruz, PhD http://kellecruz.com/ main: 917.725.1334 mobile: 917.837.9748

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Re: [AstroPy] plot of data and residuals
by Jonathan Slavin 11 আগস্ট, 2010

11 আগস্ট, 2010

Thanks for all the suggestions regarding my question on plotting data and a model with residuals. Here is the simple function I wrote which gets the jobs done for me. It's not too flexible, but it's what I wanted. Jon def plot_model(xdata,ydata,edata,ymod,dcolor='b',mcolor='g'): """ Plot data and a model on one plot and the residuals on a plot stacked below. Returns the figure object and an array of the axes objects for the main plot and the residuals plot. f,a = plot_model(xdata,ydata,edata,ymod,dcolor='b',mcolor='g') where xdata, ydata, edata are the x, y and error values for the data and ymod are the model values. The keyword arguments dcolor (color of data points) and mcolor (color of model line) are accepted. """ fig = plt.figure() ax1 = fig.add_axes([0.1,0.3,0.8,0.6]) ax2 = fig.add_axes([0.1,0.1,0.8,0.2]) # I prefer not to have horizontal "caps" on my error bars ax1.errorbar(xdata,ydata,yerr=edata,marker='o',capsize=0,color=dcolor) ax1.plot(xdata,ymod,color=mcolor) xticklabels = ax1.get_xticklabels() plt.setp(xticklabels,visible=False) resid = ydata - ymod ax2.errorbar(xdata,resid,yerr=edata,marker='o',capsize=0,color=dcolor) ax2.axhline(0.,color='k') axes = np.array([ax1,ax2]) return fig, axes

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plot of data and residuals
by Jonathan Slavin 10 আগস্ট, 2010

10 আগস্ট, 2010

To AstroPy'ers: I'd like to make a plot using matplotlib with two subplots, a larger one with the data and model and a lower (smaller height) abutting one with the residuals (sharing the x-axis). Since this is a common sort of plot in astronomy, I thought maybe one of you might have figured out how to do this, saving me the trouble of figuring it out for myself. I don't see any examples quite like that on the matplotlib examples page. If I don't get any response, I'll do it myself and (if not too kludgey) will post my method. Jon -- ______________________________________________________________ Jonathan D. Slavin Harvard-Smithsonian CfA jslavin(a)cfa.harvard.edu 60 Garden Street, MS 83 phone: (617) 496-7981 Cambridge, MA 02138-1516 cell: (781) 363-0035 USA ______________________________________________________________

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plot of data and residuals
by Fabricio Ferrari 10 আগস্ট, 2010

10 আগস্ট, 2010

Hello Jonathan in fact, there was no direct way of doing this in the pre-1.0 versions of Matplotlib. In the 1.0.0 version there is something called 'gridspec' which does exactly what you want. Anyway, if you can't install v.1.0.0 I found a way of doing this, shown below (I put only the relevant code) . . . # definitions for the axes left = 0.05 width = 0.65 bottom = 0.05 height = 0.65 bottom_h = left+width+0.02 left_h = left+width+0.02 rect_image = [left, bottom, width, height] rect_profx = [left, bottom_h, width, 0.2] rect_profy = [left_h, bottom+0.04, 0.2, height] # start with a rectangular Figure fig = P.figure(1, figsize=(8,8)) axProfX = P.axes(rect_profx) axProfX.plot(x,y) axImage = P.axes(rect_image) axImage.imshow(data,origin='lower',interpolation='nearest') axProfY = P.axes(rect_profy) axProfY.plot(x2,y2) . . . When you need to access plot properties in a particular subplot, you must invoke the functions via the axis class instances, axProfY, axProfX, and so on... ..-. ..-. Fabricio Ferrari [www.ferrari.pro.br] Universidade Federal do Pampa Bagé RS Brasil

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Does anyone here use The Software Bisque Orchestrate Program?
by Wayne Watson 9 আগস্ট, 2010

9 আগস্ট, 2010

See Subject. It's a long shot, and it is related to this list. -- Wayne Watson (Watson Adventures, Prop., Nevada City, CA) (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time) Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet "An experiment is a question which science poses to Nature, and a measurement is the recording of Nature’s answer." -- Max Planck Web Page:<www.speckledwithstars.net/>

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Re: [AstroPy] Summer scholar
by Jonathan Slavin 3 আগস্ট, 2010

3 আগস্ট, 2010

One thing that I'd like (don't know if a summer student could do it) is to improve on the multidimensional filtering/smoothing in scipy. We had some discussions about this a little while back. Specifically the ndimage.filters.uniform_filter and others in that module are implemented in multiple dimensions via a series of 1-D filters in each dimension -- which is not the same as a truly multi-dimensional filter. Maybe this is not something there is much interest in, though anyone who wants to remove some noise in a 2-D image might be interested. Jon Slavin On Tue, 2010-08-03 at 12:00 -0500, astropy-request(a)scipy.org wrote: > Message: 1 > Date: Tue, 3 Aug 2010 00:04:37 -0400 > From: Rene Breton <superluminique(a)gmail.com> > Subject: Re: [AstroPy] Summer scholar > To: astropy(a)scipy.org > Message-ID: <17371E6A-230E-4B3C-8977-115C0041E03B(a)gmail.com> > Content-Type: text/plain; charset=us-ascii > > Hi everyone, > > > Thanks for sharing your tips/library Stefano. Indeed a matching > routine would be very nice to have so people should definitely aim to > have something that makes use of several criteria such as distance and > magnitude (in a more generic way). The Groth/Stetson algorithm seems > very good but maybe yours is similar or can do better. Worse case, > both can be put in under different names a little bit like the > different root finding algorithms in scipy.optimize. You can never > have enough algorithms to get around pathological problems. > > Now, regarding Wolfgang's post, I very much agree with his ideas. I > have to say that I've already implemented the "find" from "find.pro" > in IDL's astrolib, which works really well in order to identify point > sources. At the same time, I've modernized the program so that it > takes advantage of numpy's array algebra, hence there are no slow "for > loops". Maybe other algorithms could be worked out but this one > certainly works well and it would be a shame to re-invent the wheel > and have someone redo it. I think it should have been committed in the > "pyastrolib" project that I was part of. If not, I'm very happy to add > it here. > > I'm also not very far from having a re-brewed "aper" function working, > from "aper.pro" in IDL's astrolib but there are a couple of function > dependencies that I haven't had try to code. So maybe the students > could start from there in their coding. > > Here are two ideas that I'd like to throw in for the student project, > but they also apply in a more general way: > 1. IDL's astrolib is a good start. The phot/daophot stuff from IDL's > astrolib is generally pretty good, though it would gain to be > modernized (and make use of array operations for instance). Since IDL > and python are arguably similar, it would probably be not too > difficult for someone with minimal experience to port some IDL code to > python. Then one can optimize it. > 2. Working on new photometry algorithms. Despite students may have > limited programming background, they might be clever physicists. There > are different algorithm using maximum entropy and such that can try to > optimized the number of fitted sources. Among other interesting things > would be algorithms/functions to derive photometric upper limits. This > is what annoys me most and IDL's astrolib totally misses it. For PSF > photometry, a routine that adds fake stars and tries to retrieve their > flux in order to asses upper limits would be awesome. Something should > also be done for aperture photometry. > > > Cheers, > > > Rene -- ______________________________________________________________ Jonathan D. Slavin Harvard-Smithsonian CfA jslavin(a)cfa.harvard.edu 60 Garden Street, MS 83 phone: (617) 496-7981 Cambridge, MA 02138-1516 cell: (781) 363-0035 USA ______________________________________________________________

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Re: [AstroPy] Summer scholar
by Stefano Covino 3 আগস্ট, 2010

3 আগস্ট, 2010

Hello everybody, actually, I feel a bit out of place since my programming skills are definitely limited compared to most, in not all, people writing to this list. Actually, I have so far mainly developed a set of tools which I have shared with my research team and my only goal was to make easier operations which could be performed in many other ways (http://www.merate.mi.astro.it/utenti/covino/usermanual.html). Actually, one of the problems I have to solve more often, is to efficiently match objects (entries) in different tables, usually tables retrieved from databases and so on. Time ago I had to develop a tool to derive the roto-translation solution for a set of different scientific frames with reference to a chosen image, and I applied a triangle match algorithm. It works very well, although I develop it following a sort of "quick and dirty" strategy. I think that the idea to develop and eventually distribute a pure python library able to match tables with or without hierarchical parameters (i.e. magnitude, flux, etc.) could be a good project for a set of still unexperienced programmers. Something, indeed, probably useful by itself. Cheers, Stefano

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