[SciPy-User] IO of large ASCII table data

Christopher Barker Chris.Barker@noaa....
Tue Aug 17 12:47:15 CDT 2010

Dan Lussier wrote:
> I am looking to read in large (many million rows) ASCII space
> separated tables into numpy arrays.

If it's all space separated, all one data type, and no comment lines or 
anything like that, then np.fromfile(file, sep=' ', dtype=np.float) is 
about as fast as you can get.

fromfile() is very limited for reading text files, and doesn't handle 
error cases well, but if it works, it's fast.


> In consulting the documentation the most likely candidate is
> numpy.genfromtext(...).  Is this function pure python or does it rely
> on a C extension as was the case with Miller's TableIO?

it's python, and not all that fast.


Christopher Barker, Ph.D.

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