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up vote 3 down vote favorite

I have a numpy structured array which contains string and float. I want to save this structured array as it is into a csv file. The simplified version of my procedure is like this.

    structured_array = np.zeros((1,), dtype=[('string','a20'),('float','f8')])
    structured_array['string'] = 'string'
    structured_array['float'] = 0.0
    np.savetxt('foo.csv', structured_array, delimiter=',',fmt='%s,%f')

I would expect string,0.000000 in foo.csv, but it gives me b'string',0.000000 where does this quotation mark and this b comes from? How can I get rid of it?

I can use readline() and manually get rid of this but is there any clever way to do this.

Thank you very much.

share|improve this question
    
I can't replicate... I get string,0.000000 have you got some sort of encoding set to your script? try ('string','S20') for the first field – user1121588 Jul 10 '15 at 16:04
    
@DanPatterson I can replicate, numpy 1.9.2, and changing to 'S20' has no effect. – Matthew Plourde Jul 10 '15 at 17:35
    
@MatthewPlourde my version is 1.7.x could this be a Unicode difference issue? – user1121588 Jul 10 '15 at 19:46
    
This looks like open issue #4543 – askewchan Sep 19 '15 at 3:30
up vote 1 down vote

Line 1087 in savetxt (...\lib\site-packages\numpy\lib\npio.py) has 

for row in X:
    fh.write(asbytes(format % tuple(row) + newline))

Which reveals that columns are converted to bytes before writing (hence the b prefix. It doesn't appear that this can be changed.

share|improve this answer
    
So, nothing can be done? – xiki_tempula Jul 11 '15 at 15:50

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