On Thu, May 20, 2010 at 11:33 AM, Nathann Cohen <[email protected]> wrote:
> Hello !
>
>> * As a language, Python is vastly superior to R. Python has good
>> support for object oriented programming, a very wide selection of
>> existing programs and libraries, and supports threads for handling
>> realtime data. I recently read a paper about massive contortions
>> somebody went through in trying to be build some system in R to model
>> and respond to realtime data -- this was really hard in R, since R
>> evidently doesn't have good support for threads. But of course, R +
>> Sage (via rpy2) would make it easy to combine the modeling power of R
>> with the asynchronous capabilities of Python.
>
> Just a few words on that one... I have had to stand statistics for one
> year at the university, and I really ate R from morning till
> evening... Even though I have forgotten almost all of it, there are
> still two things for which R is vastly superior to python : matrices
> and plots. This does not make it a better language than python, that's
> perfectly True, but to anyone who would like to rewrite in Sage some
> code written in R, this would mean a HUGE amount of work. The
> manipulation of matrices in R is just amazing. If you want to strip
> all the negative values contained in a matrix M, you but have to write
> M * (M > 0). How easier can it et ? There is a thousand tricks like
> that available in R that I noticed nowhere else. And the same goes for
> plottings using R. I mean that on these two points, the R language is
> much more expressive than any other I know.
You can do this with numpy arrays:
In [6]: import numpy as np
In [7]: a = np.array([[1,-2],[-2,3]]); a
Out[7]:
array([[ 1, -2],
[-2, 3]])
In [8]: a*(a>0)
Out[8]:
array([[1, 0],
[0, 3]])
--Mike
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