CountVectorizer: AttributeError: 'numpy.ndarray' object has no attribute 'lower'

Question

I have a one-dimensional array with large strings in each of the elements. I am trying to use a CountVectorizer to convert text data into numerical vectors. However, I am getting an error saying:

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

mealarray contains large strings in each of the elements. There are 5000 such samples. I am trying to vectorize this as given below:

vectorizer = CountVectorizer(
    stop_words='english',
    ngram_range=(1, 1),  #ngram_range=(1, 1) is the default
    dtype='double',
)
data = vectorizer.fit_transform(mealarray)

The full stacktrace :

File "/Library/Python/2.7/site-packages/sklearn/feature_extraction/text.py", line 817, in fit_transform
    self.fixed_vocabulary_)
  File "/Library/Python/2.7/site-packages/sklearn/feature_extraction/text.py", line 748, in _count_vocab
    for feature in analyze(doc):
  File "/Library/Python/2.7/site-packages/sklearn/feature_extraction/text.py", line 234, in <lambda>
    tokenize(preprocess(self.decode(doc))), stop_words)
  File "/Library/Python/2.7/site-packages/sklearn/feature_extraction/text.py", line 200, in <lambda>
    return lambda x: strip_accents(x.lower())
AttributeError: 'numpy.ndarray' object has no attribute 'lower'

Answer 1

Check the shape of mealarray. If the argument to fit_transform is an array of strings, it must be a one-dimensional array. (That is, mealarray.shape must be of the form (n,).) For example, you'll get the "no attribute" error if mealarray has a shape such as (n, 1).

You could try something like

data = vectorizer.fit_transform(mealarray.ravel())

Answer 2

Got the answer to my question. Basically, CountVectorizer is taking lists (with string contents) as an argument rather than array. That solved my problem.

Answer 3

A better solution is explicit call pandas series and pass it CountVectorizer():

>>> tex = df4['Text']
>>> type(tex)
<class 'pandas.core.series.Series'>
X_train_counts = count_vect.fit_transform(tex)

Next one won't work, cause its a frame and NOT series

>>> tex2 = (df4.ix[0:,[11]])
>>> type(tex2)
<class 'pandas.core.frame.DataFrame'>

Answer 4

I got the same error:

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

To solve this problem, I did the following:

1. Verify the dimension of the array with: name_of_array1.shape
2. I output is: (n,1) then use flatten() to convert an array of two-dimensional to one-dimensional: flat_array = name_of_array1.flatten()
3. Now, I can use CountVectorizer() because this works with list of one argument as a string.