[Image-SIG] How do i import text file which has NaNs ?
Christopher Barker
Chris.Barker at noaa.gov
Wed Dec 5 18:37:55 CET 2007
> The ASCII file has NaNs or NoData in them.
> I am not able to read the file into python since it is not able to
> recognize NaN.
> */[jv] I’m not sure this is applicable, but have you looked at the numpy
> extension package which has support for NaN?/*
numpy does support NaN, and it's an excellent choice for this kind of
data anyway. It's also easy to turn a numpy array into a PIL image.
However, I'm not sure it supports NaN text literals, and, if it does,
it's probably not platform independent, as it uses the system library
scanf().
I would check out numpy, but you may have to write the file scanning
code yourself, and translate the NaN.
An example might help us get other ideas. For instance, what is the
ascii representation of NaN? "NaN", or something else?
What system are you running on? For instance, on OS-X (Python 2.5,
compiled with gcc4.0.1), this works:
>>> float("NaN")
nan
But I don't think that works on the stock Windows Python. However, there
may be another literal that does. Try:
>>> import numpy as N
>>> str(N.nan)
'nan'
and it might tell you the literal on your system.
-Chris
--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
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Chris.Barker at noaa.gov
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