[SciPy-user] Data types

Tony Mannucci Tony.Mannucci at jpl.nasa.gov
Mon Mar 6 10:17:38 CST 2006

I am now learning that my installation may be lacking. Travis seemed 
to confirm that I was not necessarily making a completely silly 
mistake, so the next step would be to clean up the installation. I 
great deal of information can be provided according to the 
instructions in INSTALL.txt. It seems wrong to send that to everyone. 
Can that also be a ticket?

>Message: 5
>Date: Mon, 06 Mar 2006 00:44:35 -0700
>From: Travis Oliphant <oliphant.travis at ieee.org>
>Subject: Re: [SciPy-user] Data types
>To: SciPy Users List <scipy-user at scipy.net>
>Message-ID: <440BE863.5050306 at ieee.org>
>Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>Tony Mannucci wrote:
>>  Dear Scipy community,
>>  I cannot find a clear statement as to allowable data types, and how
>>  these are specified. I am trying to read in an array using
>>  read_array. One of the arguments of the function is "atype", to
>>  specify the dtype of the output array. I cannot figure out what
>>  format the tuple atype is in.
>While SciPy builds for NumPy, it has not been "fully" adapted in that it
>still uses a lot of Numeric idioms for data-types.
>The read_array code is still using the old concept of "typecode" which
>is a one-character string (i.e. what dtype.char gives now). 
>There may also still be bugs still in SciPy. 
>>  If Numpy is like Numeric, then, according to "Python In A Nutshell",
>>  the array objects contain a single type. So, I cannot use several
>>  values, I would specify only one value for atype. This seems to
>>  differ from the scipy online documentation, suggesting atype could be
>>  a tuple. I realize the functionality is evolving.
>In this case, the functionality was there but might have become broken
>in the transition to NumPy (or the result of an old bug).  You should be
>able to specify a tuple for data-type.  Most SciPy functions that take
>data-types need to be made aware of the new concept of data type in NumPy.
>>  Along these lines, the following works:
>>  data = ARRIN.read_array('filename',columns=(0,2),atype='d')
>>  and appears to give a double precision array (as evidenced from
>>  data.dtype.char = 'd'). However, using a few other strings for atype
>>  does not work, e.g. 'I', or 'L', etc.
>What do you get as the error?
>>  Finally, the following does not seem to work:
>>  data = ARRIN.read_array('filename',columns=(2))
>>  so reading a single column appears to cause a problem. The 
>>following DOES work:
>>  data = ARRIN.read_array('filename',columns=(0,2))
>It would be easiest if you opened a ticket and attached an example
>file.  Open tickets at

Tony Mannucci
Supervisor, Ionospheric and Atmospheric Remote Sensing Group
  Mail-Stop 138-308,                     Tel > (818) 354-1699
  Jet Propulsion Laboratory,              Fax > (818) 393-5115
  California Institute of Technology,     Email > Tony.Mannucci at jpl.nasa.gov
  4800 Oak Grove Drive,                   http://genesis.jpl.nasa.gov
  Pasadena, CA 91109

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