[SciPy-user] Data types
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?
>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
Supervisor, Ionospheric and Atmospheric Remote Sensing Group
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