[Tutor] Python vs. MATLAB

[Jaidev Deshpande]

Dear all

What advantages does Python have over MATLAB as a programming language, (not
the computing environment of MATLAB)?

Also, wikipedia says Python is an interpreted language, what does that mean?
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[Tutor] Backpropagation Learning in Python

[Jaidev Deshpande]

Dear All

Please suggest a link to tutorials for backpropagation and other neural
network training algorithms through Python.

Any other commentary is welcome, as I am new to both Python and Neural
Networks.
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[Tutor] reading large text file as numpy array

[Jaidev Deshpande]

Dear All

I have a large text file with more than 50k lines and about 784 floats in
each line.

How can I read the whole file as a single numpy array?

Also, is it possible to save a session (like in MATLAB) and reload it later?

thanks
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[Tutor] PCA on sparse matrices, tolerance of eigenvalues

[Jaidev Deshpande]

Dear all,

I tried using the 'scipy.sparse.eigs' tool for performing principal
component analysis on a matrix which is roughly 80% sparse.

First of all, is that a good way to go about it?

Second, the operation failed when the function failed to converge on
accurate eigenvalues. I noticed the 'tol' attribute in the function, but how
does one define a reasonable tolerance and calculate it?

Thanks
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[Tutor] Using Python to send signals to the USB port

[Jaidev Deshpande]

Hi

Is there some way I can use Python to send data through a USB port and
control the data in real-time?

(For instance, I can make a sinusoidal wave of a given specification, and
visualize it using NumPy / Matplotlib. How can I send the digitized form of
this array through a USB port, and then convert it back into analog so I can
view it on an oscilloscope?)

Thanks.
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[Tutor] Cython vs Python-C API

[Jaidev Deshpande]

Hi

I need to perform cubic spline interpolation over a range of points, and I
have written the code for the same in C and in Python.

The interpolation is part of a bigger project. I want to front end for the
project to be Python. Ideally I want Python only to deal with data
visualization and i/o, and I'll leave the computationally expensive part of
the project to C extensions, which can be imported as functions into Python.

To this end, the interpolation can be handled in two ways:

1. I can either compile the C code into a module using the Python-C/C++
API, through which I can simple 'import' the required function.
2. I can use the Python code and extend it using Cython.

Which will give me a better performance?

Thanls
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[Tutor] Importing functions in IPython

[Jaidev Deshpande]

Dear List,

Suppose I have a function myfunc() in a module called mymodule.py

As usual, I import this function in IPython with

In[1]: from mymodule import myfunc

Now if I find that there is something wrong with myfunc, I can open
mymodule.py with a suitable editor and make the required changes.

Now when I delete the original function and import the changed one,

In[2]: del myfunc

In[3]: from mymodule import myfunc

it doesn't work as per the new changes. I have to close IPython and
start all over again.

Is there a less cumbersome way to do this, preferably without closing IPython?

Thanks
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[Tutor] The exec command and namespaces

[Jaidev Deshpande]

Hi,

Supposed I have a string containing a python script and I exec that script.

Is there a way to keep track of the variables that this exec() command creates?

Say,

>>> s = 'for i in range(10):\n\tprint i\n\n'
>>> exec(s)
0
1
2
3
4
5
6
7
8
9

Is there a way to ascertain that the variable 'i' was created through
the exec function? I'm looking for a way to identify all python
variables that a given exec call creates.

Thanks
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