python labelencoder_python-在'float'和'str'的实例之间不支持LabelEncoder：'>'

我面临多个变量甚至处理缺失值的错误。例如：

le = preprocessing.LabelEncoder()

categorical = list(df.select_dtypes(include=['object']).columns.values)

for cat in categorical:

print(cat)

df[cat].fillna('UNK', inplace=True)

df[cat] = le.fit_transform(df[cat])

# print(le.classes_)

# print(le.transform(le.classes_))

---------------------------------------------------------------------------

TypeError Traceback (most recent call last)

in ()

4 print(cat)

5 df[cat].fillna('UNK', inplace=True)

----> 6 df[cat] = le.fit_transform(df[cat].fillna('UNK'))

7 # print(le.classes_)

8 # print(le.transform(le.classes_))

C:\Users\paula.ceccon.ribeiro\AppData\Local\Continuum\Anaconda3\lib\site-packages\sklearn\preprocessing\label.py in fit_transform(self, y)

129 y = column_or_1d(y, warn=True)

130 _check_numpy_unicode_bug(y)

--> 131 self.classes_, y = np.unique(y, return_inverse=True)

132 return y

133

C:\Users\paula.ceccon.ribeiro\AppData\Local\Continuum\Anaconda3\lib\site-packages\numpy\lib\arraysetops.py in unique(ar, return_index, return_inverse, return_counts)

209

210 if optional_indices:

--> 211 perm = ar.argsort(kind='mergesort' if return_index else 'quicksort')

212 aux = ar[perm]

213 else:

TypeError: '>' not supported between instances of 'float' and 'str'

检查导致错误的变量导致ins：

df['CRM do Médico'].isnull().sum()

0

除了nan值，什么可能导致此错误？