On Thu, May 7, 2009 at 19:36, Brennan Williams brennan.williams@visualreservoir.com wrote:

I've created an array of strings using something like....

stringarray=self.karray.astype("|S8")

If the array value is a Nan I get "1.#QNAN" in my string array.

For cosmetic reasons I'd like to change this to something else, e.g. "invalid" or "inactive".

My string array can be up to 100,000+ values.

Is there a fast way to do this?

Well, there is a print option that lets you change how nans are represented when arrays are printed. It is possible that this setting should also be used when converting to string arrays. However, it does not do so currently:

In [9]: %push_print --nanstr invalid Precision: 8 Threshold: 1000 Edge items: 3 Line width: 75 Suppress: False NaN: invalid Inf: Inf

In [10]: a = zeros(10)

In [11]: a[5] = nan

In [12]: a Out[12]: array([ 0., 0., 0., 0., 0., invalid, 0., 0., 0., 0.])

In [13]: a.astype('|S8') Out[13]: array(['0.0', '0.0', '0.0', '0.0', '0.0', 'nan', '0.0', '0.0', '0.0', '0.0'], dtype='|S8')

You will need to use the typical approach:

mask = (stringarray == '1.#QNAN') stringarray[mask] = 'invalid'

This will be wasteful of memory, so with your large array size, you might want to consider breaking it into chunks and modifying the chunks in this way.