[Numpy-discussion] newbie: attempt at data frame

[Vincent Nijs]

Based on Eike's input the dbase class can now also load and dump (simple)
csv and pickle files. See the tests at the bottom of the file and the
doc-strings.

If there is an easy way to read array data + variable names using the csv
module it would be great if that could be added to cookbook/InputOutput. I
couldn't figure out how to do it.

Eike:
I think I can figure out how to add a plot method. However, if you have some
more suggestions on how to implement the getAtTime, extract, and set methods
you mentioned that would be great.

Vincent


On 12/28/06 1:40 PM, "Vincent Nijs" <v-nijs at kellogg.northwestern.edu> wrote:

> Thanks for the input Eike.
> 
> I will add load and store methods to Pickle/UnPickle the object. I have got
> to get the data into the class first however from an ascii file (txt or
> csv).
> 
> I'd like to read the data and variable names directly from a single csv
> file. I tried this through the python csv module but it would read all data
> as strings and I couldn't figure out how to easily separate the variable
> names and the data. I you have any suggestion on how I might do this please
> let me know.
> 
> Unfortunately I don't know what a 'set' method is or would do :) Could you
> point to an example perhaps.
> 
> I like your ideas for extending the class. I'll look into that when I get
> the basic class working.
> 
> Best,
> 
> Vincent
> 
> 
> On 12/28/06 12:54 PM, "Eike Welk" <eike.welk at gmx.net> wrote:
> 
>> If your main concern is to store scientific data on disk you might
>> try: 
>> http://www.pytables.org/moin
>> 
>> However, it uses numarray internally and a C library, which you have
>> to build from source. (You use a Mac right?)
>> 
>> 
>> Concerning your code:
>> - Your two file solution seems impractical to me. I think you should
>> just pickle your whole dbase object.
>> - Maybe you should write 'load' and 'store' methods that create the
>> temporary file, Pickler and Unpickler objects.
>> -The __init__ method should then construct the object from a list of
>> variable names and an array.
>> -Offcourse you need a set method.
>> 
>> more ideas:
>> - A special variable name 'time'. Then you can implement a
>> getAtTime( varNameList, timePoint) method with interpolation.
>> - A 'plot' method that works like matplotlib's plot function.
>> - An extract(varNameList) method, that returns a new dbase object with
>> only the selected variables.
>> - A companion class that can hold several time series at once to
>> compare different experiments.
>> 
>> Finally, post the code to the mailing list. At least I would like to
>> use such a class :-).
>> 
>> Yours
>> Eike.
>> 
>> _______________________________________________
>> Numpy-discussion mailing list
>> Numpy-discussion at scipy.org
>> http://projects.scipy.org/mailman/listinfo/numpy-discussion
>> 

-- 
Vincent R. Nijs
Assistant Professor of Marketing
Kellogg School of Management, Northwestern University
2001 Sheridan Road, Evanston, IL 60208-2001
Phone: +1-847-491-4574 Fax: +1-847-491-2498
E-mail: v-nijs at kellogg.northwestern.edu
Skype: vincentnijs


-------------- next part --------------
A non-text attachment was scrubbed...
Name: dbase.py
Type: application/octet-stream
Size: 2800 bytes
Desc: not available
URL: <http://mail.python.org/pipermail/numpy-discussion/attachments/20061228/66557583/attachment.obj>