DictVectorizer doesn't raise NotFittedError when using transform without prior fitting #24816
Description
Describe the bug
When trying to call the transform method of an unfitted DictVectorizer instance an AttributeError is raised instead of a NotFittedError .
Other transformers, such as StandardScaler, make use of check_is_fitted to raise a NotFittedError.
I'm willing to make a PR to add check_is_fitted to DictVectorizer. Please let me know, if that's ok.
Steps/Code to Reproduce
from sklearn.exceptions import NotFittedError
from sklearn.feature_extraction import DictVectorizer
feat_dict = [{'col1': 'a', 'col2': 'x'},{'col1': 'b', 'col2': 'y'}]
dv = DictVectorizer()
try:
dv.transform(feat_dict)
except NotFittedError as e:
print("DictVectorizer is not fitted yet.")Expected Results
NotFittedError is raised, because transform method was called without prior fitting.
Actual Results
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
Cell In [4], line 8
5 dv = DictVectorizer()
7 try:
----> 8 dv.transform(feat_dict)
9 except NotFittedError as e:
10 print("DictVectorizer is not fitted yet.")
File ~/../lib/python3.11/site-packages/sklearn/feature_extraction/_dict_vectorizer.py:373, in DictVectorizer.transform(self, X)
356 def transform(self, X):
357 """Transform feature->value dicts to array or sparse matrix.
358
359 Named features not encountered during fit or fit_transform will be
(...)
371 Feature vectors; always 2-d.
372 """
--> 373 return self._transform(X, fitting=False)
File ~/.../lib/python3.11/site-packages/sklearn/feature_extraction/_dict_vectorizer.py:207, in DictVectorizer._transform(self, X, fitting)
205 vocab = {}
206 else:
--> 207 feature_names = self.feature_names_
208 vocab = self.vocabulary_
210 transforming = True
AttributeError: 'DictVectorizer' object has no attribute 'feature_names_'Versions
System:
python: 3.11.0 (main, Oct 24 2022, 19:56:13) [GCC 11.2.0]
executable: /home/user/.cache/pypoetry/virtualenvs/sklean-dev-SgMhZBSc-py3.11/bin/python
machine: Linux-5.10.102.1-microsoft-standard-WSL2-x86_64-with-glibc2.35
Python dependencies:
sklearn: 1.1.3
pip: 22.3
setuptools: 65.5.0
numpy: 1.23.4
scipy: 1.9.3
Cython: None
pandas: 1.5.1
matplotlib: 3.6.0
joblib: 1.2.0
threadpoolctl: 3.1.0
Built with OpenMP: True