AttributeError: module '__main__' has no attribute 'AverageWordLengthExtractor'

Question

I have created one custom transformer class AverageWordLengthExtractor in my pipeline code and saved the model after running it successfully. Now, when I am trying to load the model using a flask app, it is giving AttributeError: module '__main__' has no attribute 'AverageWordLengthExtractor'

pipeline code that runs successfully and saves the model

custom class

class AverageWordLengthExtractor(BaseEstimator, TransformerMixin):
    
    def __init__(self):
        pass
    def average_word_length(self, text):
        return np.mean([len(word) for word in text.split( ) if word not in stopWords])
    def fit(self, x, y=None):
        return self
    def transform(self, x , y=None):
        return pd.DataFrame(pd.Series(x).apply(self.average_word_length)).fillna(0)

saving the model

def save_model(model, model_filepath):
    # Save best grid search pipeline to file
    dump_file = model_filepath
    joblib.dump(model, dump_file, compress=1)

this above code runs successfully.

Now, I am trying to load the model using flask.

app = Flask(__name__)
....
....
# load model
model = joblib.load("../models/classifier2.pkl")

I am trying to predict using this model, but it is giving the error,

$ python run.py
Traceback (most recent call last):
  File "run.py", line 33, in <module>
    model = joblib.load("../models/classifier2.pkl")
  File "C:\Users\609775743\AppData\Local\Continuum\anaconda3\lib\site-packages\sklearn\externals\joblib\numpy_pickle.py", line 578, in load
    obj = _unpickle(fobj, filename, mmap_mode)
  File "C:\Users\609775743\AppData\Local\Continuum\anaconda3\lib\site-packages\sklearn\externals\joblib\numpy_pickle.py", line 508, in _unpickle
    obj = unpickler.load()
  File "C:\Users\609775743\AppData\Local\Continuum\anaconda3\lib\pickle.py", line 1050, in load
    dispatch[key[0]](self)
  File "C:\Users\609775743\AppData\Local\Continuum\anaconda3\lib\pickle.py", line 1338, in load_global
    klass = self.find_class(module, name)
  File "C:\Users\609775743\AppData\Local\Continuum\anaconda3\lib\pickle.py", line 1392, in find_class
    return getattr(sys.modules[module], name)
AttributeError: module '__main__' has no attribute 'AverageWordLengthExtractor'

: The code works fine without a custom class.：代码在没有自定义类的情况下工作正常。

Answer 1

have you imported the class AverageWordLengthExtractor in you flask app? eg

import joblib
from average_word_length_extractor import AverageWordLengthExtractor
app = Flask(__name__)
# ...
# ...
# load model
model = joblib.load("../models/classifier2.pkl")

average_word_length_extractor is the Python file where your AverageWordLengthExtractor class is. In this case: average_word_length_extractor.py