numpy-discussion

[Numpy-discussion] matrix file format

[Peter I. H. <pi...@oe...>]

Hi,

I'm trying to find out what format a matrix input file should have in
numpy.
example :

I have the matrix :
[[1 2 3
   4 5 6
   7 8 9]]

and want to read it to nympy from a text-filen that is easy for a user
to generate in an editor.

Can you tell me how to do that. I read the manual and it didnøt given
much af on idea.

I thank you in advance

Peter I. Hansen

Re: [Numpy-discussion] matrix file format

[Janko H. <jh...@if...>]

In principle there is no such format in the sense of other numerical
environments. But it is possible to simple put the data into a python
module and import that, like

# Datafile data.py
import Numeric
data=Numeric.array([[1,2,3],[4,5,6],[7,8,9]])

# in python (other module or interactive session)
from data import data
print data

HTH
__Janko


Peter I. Hansen writes:
 > Hi,
 > 
 > I'm trying to find out what format a matrix input file should have in
 > numpy.
 > example :
 > 
 > I have the matrix :
 > [[1 2 3
 >    4 5 6
 >    7 8 9]]
 > 
 > and want to read it to nympy from a text-filen that is easy for a user
 > to generate in an editor.
 > 
 > Can you tell me how to do that. I read the manual and it didnøt given
 > much af on idea.
 > 
 > I thank you in advance
 > 
 > Peter I. Hansen
 > 
 > _______________________________________________
 > Numpy-discussion mailing list
 > Num...@li...
 > http://lists.sourceforge.net/mailman/listinfo/numpy-discussion

[Numpy-discussion] matrix file format

[Christopher L. <cl...@gn...>]

You have many options:  

I frequently use Konrad Hinsen's "Scientific" package
(http://dirac.cnrs-orleans.fr/programs/scientific.html).  It make importing
files from user input or other packages like matlab easy and supports
several file formats.  The simpliest is a basic white-space-delimitted text file

if you have a text file "arrayfile.txt" that looks like this:

# arrayfile.txt (lines beginning  with '#' are ignored)
1 2 3
4 5 6
6 8 9

You can fire up python and read in your matrix like this:

   >>> from Scientific.IO.ArrayIO import readArray
   >>> A = readArray('arrayfile.txt')
   >>> print A
   [[1 2 3]
    [4 5 6]
    [6 8 9]]

Re: [Numpy-discussion] matrix file format

[Konrad H. <hi...@cn...>]

> I'm trying to find out what format a matrix input file should have in
> numpy.

Any format you like, but you have to supply the I/O code yourself.
Which however is really simple. For example, the following
function from ScientificPython:

  from Scientific.IO.TextFile import TextFile
  import string, Numeric

  def readArray(filename):
      "Return an array containing the data from file |filename|."
      data = []
      for line in TextFile(filename):
	  if line[0] != '#':
	      data.append(map(eval, string.split(line)))
      a = Numeric.array(data)
      if a.shape[0] == 1 or a.shape[1] == 1:
	  a = Numeric.ravel(a)
      return a

Konrad.
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