diff --git a/requirements.txt b/requirements.txt
index 478adcb..514c44f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -11,3 +11,4 @@ setuptools==66.0.0
 spacy==3.5.3
 tqdm==4.65.0
 tabulate==0.9.0
+xgboost==2.0.3
\ No newline at end of file
diff --git a/sinr/text/evaluate.py b/sinr/text/evaluate.py
index c976ea1..d39d351 100644
--- a/sinr/text/evaluate.py
+++ b/sinr/text/evaluate.py
@@ -3,11 +3,13 @@
 import scipy
 from scipy import stats
 from sklearn.datasets._base import Bunch
+import sklearn.metrics as metrics
 import pandas as pd
 import urllib.request
 import os
 from tqdm.auto import tqdm
 import time
+import xgboost as xgb
 
 def fetch_data_MEN():
     """Fetch MEN dataset for testing relatedness similarity
@@ -283,3 +285,110 @@ def dist_ratio_dim(sinr_vec, dim, union=None, prctbot=50, prcttop=10, nbtopk=5,
             print("dimension",dim,"inter nulle", topks)
             return 0
         return intra / inter
+
+def vectorizer(sinr_vec, X, y=[]):
+    """Vectorize preprocessed documents to sinr embeddings
+    
+    :param sinr_vec: SINrVectors object
+    :type sinr_vec: SINrVectors
+    :param X: preprocessed documents
+    :type X: text (list(list(str))): A list of documents containing words
+    :param y: documents labels
+    :type y: numpy.ndarray
+    
+    :returns: list of vectors
+    """
+    
+    if len(y) > 0 and len(X) != len(y):
+        raise ValueError("X and y must be the same size")
+    
+    indexes = set()
+    vectors = list()
+    
+    # Doc to embedding
+    for i, doc in enumerate(X):
+        doc_vec = [sinr_vec._get_vector(sinr_vec._get_index(token)) for token in doc if token in sinr_vec.vocab]
+        if len(doc_vec) == 0:
+            indexes.add(i)
+        else:
+            vectors.append(np.mean(doc_vec, axis=0))
+        
+    # Delete labels of:
+    #- empty documents
+    #- documents with only unknown vocabulary
+    if len(y) > 0:
+        y = np.delete(y, list(indexes))
+        y = list(map(int,y))
+          
+    return vectors, y
+
+def clf_fit(X_train, y_train, clf=xgb.XGBClassifier()):
+    """Fit a classification model according to the given training data.
+    :param X_train: training data
+    :type X_train: list of vectors
+    :param y_train: labels
+    :type y_train: numpy.ndarray
+    :param clf: classifier
+    :type clf: classifier (ex.: xgboost.XGBClassifier, sklearn.svm.SVC)
+    
+    :returns: Fitted classifier
+    :rtype: classifier
+    """
+    clf.fit(X_train, y_train)
+    return clf
+
+def clf_score(clf, X_test, y_test, scoring='accuracy', params={}):
+    """Evaluate classification on given test data.
+    :param clf: classifier
+    :type clf: classifier (ex.: xgboost.XGBClassifier, sklearn.svm.SVC)
+    :param X_test: test data
+    :type X_test: list of vectors
+    :param y_test: labels
+    :type y_test: numpy.ndarray
+    :param scoring: scikit-learn scorer object, default='accuracy'
+    :type scoring: str
+    :param params: parameters for the scorer object
+    :type params: dictionary
+    
+    :returns: Score
+    :rtype: float
+    """
+    score = getattr(metrics, scoring+'_score')
+    y_pred = clf.predict(X_test)
+    return score(y_test, y_pred, **params)
+
+def clf_xgb_interpretability(sinr_vec, xgb, interpreter,topk_dim=10, topk=5, importance_type='gain'):
+    """Interpretability of main dimensions used by the xgboost classifier
+    :param sinr_vec: SINrVectors object from which datas were vectorized
+    :type sinr_vec: SINrVectors
+    :param xgb: fitted xgboost classifier
+    :type xgb: xgboost.XGBClassifier
+    :param interpreter: whether stereotypes or descriptors are requested
+    :type interpreter: str
+    :param topk_dim: Number of features requested among the main features used by the classifier (Default value = 10)
+    :type topk_dim: int
+    :param topk: `topk` value to consider on each dimension (Default value = 5)
+    :type topk: int
+    :param importance_type: ‘weight’: the number of times a feature is used to split the data across all trees,
+                            ‘gain’: the average gain across all splits the feature is used in,
+                            ‘cover’: the average coverage across all splits the feature is used in,
+                            ‘total_gain’: the total gain across all splits the feature is used in
+                            ‘total_cover’: the total coverage across all splits the feature is used in
+    :type importance_type: str
+    
+    :returns: Interpreters of dimensions, importance of dimensions
+    :rtype: list of set of object, list of tuple
+
+    """
+    
+    features = xgb.get_booster().get_score(importance_type=importance_type)
+    features = dict(sorted(features.items(), key=lambda x: x[1], reverse=True))
+    features_index = [int(f[1:]) for f in list(features.keys())[:topk_dim]]
+    features_importance = list(features.items())[:topk_dim]
+    
+    if interpreter=='descriptors':
+        dim = [sinr_vec.get_dimension_descriptors_idx(index, topk=topk) for index in features_index]
+    elif interpreter=='stereotypes':
+        dim = [sinr_vec.get_dimension_stereotypes_idx(index, topk=topk) for index in features_index]
+    
+    return dim, features_importance
diff --git a/sinr/text/preprocess.py b/sinr/text/preprocess.py
index 87b3b8f..d5dcae3 100644
--- a/sinr/text/preprocess.py
+++ b/sinr/text/preprocess.py
@@ -117,7 +117,7 @@ def do_txt_to_vrt(self, separator='sentence'):
         if separator=='sentence':
             input_txt = input_file.read().splitlines()  # Read INPUT_FILE
         else:
-            input_txt = input_file.read().split(separator)
+            input_txt = input_file.read().split(separator)[1:] # First tag make an empty document
         logger.info(str(len(input_txt)) + "lines to preprocess")
         input_file.close()
         
@@ -158,7 +158,7 @@ def do_txt_to_vrt(self, separator='sentence'):
         corpus_opened.close()
         logger.info(f"VRT-style file written in {self.corpus_output.absolute()}")
 
-def extract_text(corpus_path, exceptions_path=None, lemmatize=True, stop_words=False, lower_words=True, number=False, punct=False, exclude_pos=[], en="chunking", min_freq=50, alpha=True, exclude_en=[], min_length_word=3):
+def extract_text(corpus_path, exceptions_path=None, lemmatize=True, stop_words=False, lower_words=True, number=False, punct=False, exclude_pos=[], en="chunking", min_freq=50, alpha=True, exclude_en=[], min_length_word=3, min_length_doc=2):
     """Extracts the text from a VRT corpus file.
 
     :param corpus_path: str
@@ -174,6 +174,8 @@ def extract_text(corpus_path, exceptions_path=None, lemmatize=True, stop_words=F
     :param exclude_en: list (Default value = [])
     :param lower_words:  (Default value = True)
     :param min_length_word:  (Default value = 3)
+    :param min_length_doc: The minimal number of token for a document (or sentence) to be kept (Default value = 2)
+    :type min_length_doc: int
     :returns: text (list(list(str))): A list of documents containing words
 
     """
@@ -200,7 +202,7 @@ def extract_text(corpus_path, exceptions_path=None, lemmatize=True, stop_words=F
         if line.startswith("<s>"):
             document = []
         elif line.startswith("</s>"):
-            if len(document) > 2:
+            if len(document) > min_length_doc:
                 out.append(document)
         elif len(pattern.findall(line)) > 0:
             pass
diff --git a/tests/test_preprocess.py b/tests/test_preprocess.py
index 278000b..dfcf834 100644
--- a/tests/test_preprocess.py
+++ b/tests/test_preprocess.py
@@ -11,6 +11,7 @@
 from sklearn.datasets import fetch_20newsgroups
 
 
+
 class TestSinr_embeddings(unittest.TestCase):
     """Tests for `graph_embeddings` package."""
 
@@ -19,6 +20,8 @@ def setUp(self):
         
         txt_path = './ppcs_test.txt'
         vrt_path = './ppcs_test.vrt'
+        txt_empty_docs_path = './ppcs_test_empty_docs.txt'
+        vrt_empty_docs_path = './ppcs_test_empty_docs.vrt'
         doc_separator = '##D'
         s0 = doc_separator + " At 10 a.m, in the heart of New York City, John Smith walked briskly towards the Empire State Building. "
         text = ( s0 +
@@ -38,8 +41,13 @@ def setUp(self):
         with open(txt_path, 'w+') as file:
             file.write(text)
         file.close()
+        with open(txt_empty_docs_path, 'w+') as file:
+            file.write(doc_separator + ' ' + doc_separator + ' ' + doc_separator + ' ' + doc_separator + ' ')
+        file.close()
         self.txt_path = txt_path
         self.vrt_path = vrt_path
+        self.txt_empty_docs_path = './ppcs_test_empty_docs.txt'
+        self.vrt_empty_docs_path = './ppcs_test_empty_docs.vrt'
         self.n_doc = 4
         self.n_sent = 10
         self.doc_separator = doc_separator
@@ -48,7 +56,11 @@ def setUp(self):
     def tearDown(self):
         """Tear down test fixtures, if any."""
         os.remove(self.txt_path)
-        os.remove(self.vrt_path)
+        os.remove(self.txt_empty_docs_path)
+        if os.path.isfile(self.vrt_path):
+            os.remove(self.vrt_path)
+        else:
+            os.remove(self.vrt_empty_docs_path)
     
     def test_doc_separator(self):
         """Testing if the preprocessed datas have the right number of documents"""
@@ -98,6 +110,16 @@ def test_preprocessed(self):
                             ok.append(token.text.lower() == s[ind])
                             
         self.assertTrue(False not in ok)
+        
+    def test_preprocessing_empty_docs(self):
+        """Testing min_length_doc = -1 : documents of all sizes are kept"""
+        vrt_maker = ppcs.VRTMaker(ppcs.Corpus(ppcs.Corpus.REGISTER_WEB,
+                                  ppcs.Corpus.LANGUAGE_EN,
+                                  self.txt_empty_docs_path),
+                                  ".", n_jobs=8, spacy_size='sm')
+        vrt_maker.do_txt_to_vrt(separator=self.doc_separator)
+        docs = ppcs.extract_text(self.vrt_empty_docs_path, min_freq=1, min_length_doc=-1)
+        self.assertTrue(len(docs) == self.n_doc)
             
         
 if __name__ == '__main__':
diff --git a/tests/test_sinr_evaluate.py b/tests/test_sinr_evaluate.py
index 91eadcd..4d280bf 100644
--- a/tests/test_sinr_evaluate.py
+++ b/tests/test_sinr_evaluate.py
@@ -7,7 +7,7 @@
 import unittest
 
 import sinr.graph_embeddings as ge
-from sinr.text.evaluate import fetch_data_MEN, fetch_data_WS353, eval_similarity, similarity_MEN_WS353_SCWS
+from sinr.text.evaluate import fetch_data_MEN, fetch_data_WS353, eval_similarity, similarity_MEN_WS353_SCWS, vectorizer, clf_fit, clf_score
 import urllib.request
 import os
 
@@ -30,6 +30,17 @@ def setUp(self):
         vectors = ge.SINrVectors('oanc')
         vectors.load()
         self.vectors = vectors
+        
+        # datas for classification 
+        X_train = [['goodbye', 'please', 'love'],[],['no', 'yes', 'friend', 'family', 'happy'],['a', 'the'],['beautiful','small','a']]
+        y_train = [0,0,1,0,1]
+        X_test = [['goodbye', 'family', 'friend'],['beautiful', 'small'],['please','happy','love']]
+        y_test = [0,1,0]
+        
+        self.X_train = X_train
+        self.y_train = y_train
+        self.X_test = X_test
+        self.y_test = y_test
 
     def tearDown(self):
         """Tear down test fixtures, if any."""
@@ -43,6 +54,20 @@ def test_similarity_MEN_WS353_SCWS(self):
         self.assertGreater(round(res["MEN"],2), 0.38)
         self.assertGreater(round(res["WS353"],2), 0.40)
         self.assertGreater(round(res["SCWS"],2), 0.38)
+    
+    def test_vectorize(self):
+        X, y = vectorizer(self.vectors, self.X_train, y=self.y_train)
+        self.assertTrue(len(X) == len(y))
+    
+    def test_clf_fit_and_score(self):
+        X_train, y_train = vectorizer(self.vectors, self.X_train, y=self.y_train)
+        X_test, y_test = vectorizer(self.vectors, self.X_test, y=self.y_test)
+        
+        clf = clf_fit(X_train, y_train)
+        score = clf_score(clf, X_test, y_test)
+        
+        self.assertTrue(score <= 1 and score >= 0)
+        
 
 if __name__ == '__main__':
     unittest.main()
\ No newline at end of file