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

Lou Pecora lou_boog2000@yahoo....
Mon Dec 8 14:54:18 CST 2008

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"

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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