[SciPy-user] Update to my SciPy document

Francesc Altet falted at pytables.org
Thu Jun 22 14:11:34 CDT 2006


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Subject: Re: [SciPy-user] Update to my SciPy document
Date: Dijous 22 Juny 2006 20:53
From: Francesc Altet <faltet at carabos.com>
To: scipy-user at scipy.net

A Dijous 22 Juny 2006 20:00, Dave Kuhlman va escriure:
> I've made a few minor updates to my SciPy document.  And, with the
> help of Nicky Van Foreest, I've also added an example to the
> section on stats.  You can find it here:
>
>     http://www.rexx.com/~dkuhlman/scipy_course_01.html
>
> Comments and suggestions are welcome.

Good stuff indeed.  Regarding PyTables section:

- From PyTables 1.3 on, NumPy (and hence SciPy) arrays are supported right
 out of the box in Array objects (the ones you are using). So, if you write a
 NumPy array, you will get a NumPy array (the same goes for Numeric and
 numarray). In other objects (EArray, VLArray or Table) you can make use of
 the 'flavor' parameter in constructors to tell PyTables: 'Hey, every time
 that I read from this object, please, return me an (rec)array with the
 appropriate flavor'. Of course, PyTables will try hard to avoid doing data
 copies in conversions (i.e. the array protocol is used whenever possible).

- The procedure for installation can be simplified somewhat:

$ tar xvzf orig/pytables-1.3.2.tar.gz
$ cd pytables-1.3.2
$ python setup.py build
$ sudo python setup.py install

- Perhaps a nice feature of PyTables that you could document is its
 capability to read slices of arrays directly from disk. You can do this by
 providing the start, stop and step parameters to node.read() method, but it
 would be more appropriate (specially when dealing with multidimensional
 data) using the __getitem__ method that expose all the data nodes. Examples:
node[1]   # Get the first element of potentially multidimensional node
node[1:4:3]  # Get an slice
node[1:4:3, 2:10:2, ..., 3]  # The complete syntax for slices is supported.

Cheers!

--

>0,0<   Francesc Altet     http://www.carabos.com/

V   V   Cárabos Coop. V.   Enjoy Data
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