data type and logarithm

[simona bellavista]

Hi, I am quite new to python and I am trying to do some simple plots.
I am using python Python 2.6.4 and numpy/1.5.1
I have an ASCII  data file that I am reading with the following lines
of code:

import pylab
import numpy as np

filename='something.dat'
file = open(filename)

rho = np.array([], dtype = 'float64')
entropy = np.array([], dtype = 'float64')
for line in file:
columns = line.split()
rho = np.append(rho,columns[0])
entropy = np.append(entropy,columns[1])

and rho and entropy are apparently read correctly, but when I look to
the data type

print rho.dtype
print entropy.dtype

I get  |S22 , what's that?
Then I want to plot a logarithmic plot and I do

pylab.plot(np.log(rho), entropy)

and I get

NotImplementedError: Not implemented for this type

Does anybody has a clue? I do not know how to proceed

Many thanks
-- 
http://mail.python.org/mailman/listinfo/python-list

genfromtxt and comment identifier

[simona bellavista]

Hi All,

I have a problem with reading data from a file using genfromtxt of
numpy module.

I have prepared a minimal example similar to the ones presented in

http://docs.scipy.org/doc/numpy/user/basics.io.genfromtxt.html#splitting-the-lines-into-columns

The script is

import numpy as np
from StringIO import StringIO
file = open('esempio.dat')
for line in file.xreadlines() :
if not line : break
print line
np.genfromtxt(StringIO(line), comments="#", delimiter=",")

I have a data file - esempio.dat - like the following:

#
# Skip me !
# Skip me too !
1, 2
3, 4
5, 6 #This is the third line of the data
7, 8
# And here comes the last line
9, 0
"""

The code is breaking at the first line, it looks like it doesn't
recognize # like comment identifier.

The error in the python interpreter is

Traceback (most recent call last):
  File "", line 1, in 
  File "esempio.py", line 7, in 
np.genfromtxt(StringIO(line), comments="#", delimiter=",")
  File "/opt/numpy/1.5.1/lib/python2.6/site-packages/numpy/lib/
npyio.py", line 1174, in genfromtxt
raise IOError('End-of-file reached before encountering data.')
IOError: End-of-file reached before encountering data.


It is clear that I haven't understood something, what am I doing
wrong?

Cheers
-- 
http://mail.python.org/mailman/listinfo/python-list

best parallelisation strategy on python

[simona bellavista]

I have a code fortran 90 that is parallelised with MPI. I would like to 
traslate it in python, but I am not sure on the parallelisation strategy and 
libraries. I work on clusters, with each node with 5GB memory and 12 processors 
or 24 processors (depending on the cluster I am using). Ideally I would like to 
split the computation on several nodes.

Let me explain what this code does: It read ~100GB data, they are divided in 
hdf5 files of ~25GB each. The code should read the data, go through it and then 
select a fraction of the data, ~1GB and then some CPU intensive work on it, and 
repeat this process many times, say 1000 times, then write the results to a 
single final file.

I was thinking that the CPU intensive part would be written as a shared object 
in C.

Do you have suggestions about which library to use?
-- 
https://mail.python.org/mailman/listinfo/python-list

scientific notation in legend (pylab)

[simona bellavista]

Hi,

I I would like to have numbers expressed in scientific notation in
legend annotations. Does anybody know how to do that?

Cheers,

S.
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: scientific notation in legend (pylab)

[simona bellavista]

thank you, I am trying to learn python, but I am having a hard to find
a good introduction to it.

On Jan 15, 3:27 am, Jason Friedman  wrote:
>
> Not sure why legend annotations makes the problem different, but
> perhaps this is a start:
-- 
http://mail.python.org/mailman/listinfo/python-list