[Numpy-discussion] What to use to read and write numpy arrays to a file?

Matthieu Brucher matthieu.brucher@gmail....
Mon Dec 8 14:56:40 CST 2008


Hi,

The repr - eval pair does not work with numpy. You can simply do a
tofile() from file().

Matthieu

2008/12/8 Lou Pecora <lou_boog2000@yahoo.com>:
> In looking for simple ways to read and write data (in a text readable format) to and from a file and later restoring the actual data when reading back in, I've found that numpy arrays don't seem to play well with repr and eval.
>
> E.g. to write some data (mixed types) to a file I can do this (fp is an open file),
>
>  thedata=[3.0,-4.9+2.0j,'another string']
>  repvars= repr(thedata)+"\n"
>  fp.write(repvars)
>
> Then to read it back and restore the data each to its original type,
>
>  strvars= fp.readline()
>  sonofdata= eval(strvars)
>
> which gives back the original data list.
>
> BUT when I try this with numpy arrays in the data list I find that repr of an array adds extra end-of-lines and that messes up the simple restoration of the data using eval.
>
> Am I missing something simple?  I know I've seen people recommend ways to save arrays to files, but I'm wondering what is the most straight-forward?  I really like the simple, pythonic approach of the repr - eval pairing.
>
> Thanks for any advice. (yes, I am googling, too)
>
>
> -- Lou Pecora,   my views are my own.
>
>
>
>
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