numpy-discussion

[Numpy-discussion] reading matrix from a file

[amit s. <ami...@ya...>]

Hi,
  i have a file with following format: 
 1 2 
 3 9 
 2 3 
 4 4 
   I want to read it and then store the values into two matrices, s.t. 
 A=[1 2;3 9] 
 B=[2 3;4 4] 
 
  Can anyone tell me how to do this in python?
 thanks 
 Amit 
  
 
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Re: [Numpy-discussion] reading matrix from a file

[Francesc A. <fa...@ca...>]

A Dimecres 08 Novembre 2006 13:42, amit soni escrigu=C3=A9:
> Hi,
>   i have a file with following format:
>  1 2
>  3 9
>  2 3
>  4 4
>    I want to read it and then store the values into two matrices, s.t.
>  A=3D[1 2;3 9]
>  B=3D[2 3;4 4]
>
>   Can anyone tell me how to do this in python?
>  thanks
>  Amit

There are many possibilities. One of them could be:

In [64]: a =3D []; b =3D []

In [65]: for i, line in enumerate(file("/tmp/data.txt")):
   ....:     if i < 2:
   ....:         a.extend([float(n) for n in line.split()])
   ....:     else:
   ....:         b.extend([float(n) for n in line.split()])
   ....:

In [66]: A=3Dnumpy.array(a).reshape(2,2); B=3Dnumpy.array(b).reshape(2,2)

In [67]: A, B
Out[67]:
(array([[ 1.,  2.],
       [ 3.,  9.]]),
 array([[ 2.,  3.],
       [ 4.,  4.]]))


HTH,

=2D-=20
>0,0<   Francesc Altet =C2=A0 =C2=A0 http://www.carabos.com/
V   V   C=C3=A1rabos Coop. V. =C2=A0=C2=A0Enjoy Data
 "-"

Re: [Numpy-discussion] reading matrix from a file

[Charles R H. <cha...@gm...>]

On 11/8/06, Francesc Altet <fa...@ca...> wrote:
>
> A Dimecres 08 Novembre 2006 13:42, amit soni escrigu=E9:
> > Hi,
> >   i have a file with following format:
> >  1 2
> >  3 9
> >  2 3
> >  4 4
> >    I want to read it and then store the values into two matrices, s.t.
> >  A=3D[1 2;3 9]
> >  B=3D[2 3;4 4]
> >
> >   Can anyone tell me how to do this in python?
> >  thanks
> >  Amit


Try

In [8]: tmp =3D fromfile('tmp.txt', sep=3D' ', dtype=3Dint)

In [9]: a =3D tmp[:4].reshape(2,2)

In [10]: b =3D tmp[4:].reshape(2,2)

In [11]: a
Out[11]:
array([[1, 2],
       [3, 9]])

In [12]: b
Out[12]:
array([[2, 3],
       [4, 4]])

Chuck

Re: [Numpy-discussion] reading matrix from a file

[Francesc A. <fa...@ca...>]

A Dimecres 08 Novembre 2006 15:55, Charles R Harris escrigu=C3=A9:
> Try
>
> In [8]: tmp =3D fromfile('tmp.txt', sep=3D' ', dtype=3Dint)
>
> In [9]: a =3D tmp[:4].reshape(2,2)
>
> In [10]: b =3D tmp[4:].reshape(2,2)
>
> In [11]: a
> Out[11]:
> array([[1, 2],
>        [3, 9]])
>
> In [12]: b
> Out[12]:
> array([[2, 3],
>        [4, 4]])

Yeah. Much, much better indeed.

=2D-=20
>0,0<   Francesc Altet =C2=A0 =C2=A0 http://www.carabos.com/
V   V   C=C3=A1rabos Coop. V. =C2=A0=C2=A0Enjoy Data
 "-"