Append string to a numpy ndarray

Question

I'm working with a numpy array called "C_ClfGtLabels" in which 374 artist/creator names are stored. I want to append a 375th artist class with a string "other artists". I thought I could just do that as follows:

C_ClfGtLabels.append('other artists')

However, this results in the following error:

AttributeError: 'numpy.ndarray' object has no attribute 'append'

I saw found this problem a few times on stackoverflow, to which the answer in one case was to use concatenate instead of append. When I tried that I got the following error:

TypeError: don't know how to convert scalar number to int

It seems to be a problem that the datatype does not match the datatype that I, trying to append/concatenate, which would be of type string. However, I don't know what I should do to make them match. The data inside the Clabels array is as follows:

    [u"admiral, jan l'" u'aldegrever, heinrich' u'allard, abraham'
 u'allard, carel' u'almeloveen, jan van' u'altdorfer, albrecht'
 u'andriessen, jurriaan' u'anthonisz., cornelis' u'asser, eduard isaac' ..]

Any advice on how I can setup the "other artists" string so that I can append it to C_ClfGtLabels?

what is the shape and the dtype of your C_ClfGtLabels numpy array? what do you mean by C_ClfGtLabels.np.append('other artists')? — farhawa
– farhawa, Commented May 20, 2015 at 13:40
The shape of the array is (374,), the dtype seems to be unsigned int (.dtype returns <u58). Oops, I meant C_ClfGtLabels.append instead of C_ClfGtLabels.np.append. I just want to append the string "other artists" to the array. — KoenCuijp
– KoenCuijp, Commented May 20, 2015 at 13:56
you could probably work on a list instead: lst = list(C_ClfGtLabels) if you really need, you can always convert it back later np.asarray(lst) — P.R.
– P.R., Commented May 20, 2015 at 14:06
The .np was a mistake, ignore that (I just removed it from my question). The output of the C_ClfGtlabels is as displayed in the last block of the question. Still, to answer your question, the output of C_ClfGtLabels.np is " 'numpy.ndarray' object has no attribute 'np' " — KoenCuijp
– KoenCuijp, Commented May 20, 2015 at 14:09

P.R. · Accepted Answer · 2015-05-20 14:17:55Z

3

A quick workaround is to convert your C_ClfGtLabels into a list first, append, and convert it back into an ndarray

lst = list(C_ClfGtLabels)
lst.append('other artists')

C_ClfGtLabels = np.asarray(lst)

answered May 20, 2015 at 14:17

P.R.

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