Nonetype 对象没有 lower 属性

Question

AttributeError: 'NoneType' 对象没有属性 'lower'

谁能帮我弄清楚如何解决这个错误！？

搜索了很多次，但似乎没有任何效果。

for feature in features:
  df[feature] = df[feature].replace('-',None)

def combine_features(row):
  try: 
    return row['genre']+ " " + row['star'] +" " + row['name'] +" " +row[' rating'] +" "+ row['director']
  except:
    print ("Error",row)

df["Combined_features"] = df.apply(combine_features,axis = 1)
print("Combined Features",df["Combined_features"].head())

cv = CountVectorizer()
count_matrix = cv.fit_transform(df["Combined_features"])
#here it gives error NoneType object has no attribute 'lower'

cosine_sim = cosine_similarity(count_matrix)
movie_user_likes = "Avatar"

Answer 1

In [52]: None.lower()
Traceback (most recent call last):
  File "<ipython-input-52-bdce891aab80>", line 1, in <module>
    None.lower()
AttributeError: 'NoneType' object has no attribute 'lower'

cv.fit_transform(df["Combined_features"]) 显然这个fit 需要可以转换为小写的字符串值（因此忽略大小写的区别）。并且 df 列/系列必须有多个字符串，至少有一个 None 元素。您有责任确保提供给 fit 的数据符合其预期。

当您创建该列时，您是否收到任何“错误”报告？在这种情况下，combine 函数将返回 None。