运行我的数据的无监督图，我注意到一个双曲线（“回旋镖”）形状：

dim=2

vectorizer = TfidfVectorizer(min_df=5, max_df = 0.4, stop_words = 'english')
train_tf_idf = vectorizer.fit_transform(bunch_train.data)
svd = TruncatedSVD(n_components=dim,random_state=42)
svd_train = svd.fit_transform(train_tf_idf)
svd_train = Normalizer().fit_transform(svd_train)

labels = {
        0:'alt.atheism',
        1:'comp.graphics',
        2:'sci.med'}
y = np.vectorize(labels.get)(bunch_train.target)

with plt.style.context('seaborn-whitegrid'):
    plt.figure(figsize=(12, 8))
    for lab, col in zip(('alt.atheism', 'comp.graphics', 'sci.med'),
                        ('blue', 'red', 'green')):
        plt.scatter(svd_train[y==lab, 0],
                    svd_train[y==lab, 1],
                    label=lab,
                    c=col)

    plt.title('2D SVD on TF-IDF - 3-NewsGroups',size=28)
    plt.xlabel('PC1')
    plt.ylabel('PC2')
    plt.legend(loc='upper left',prop={'size': 20})
    plt.tight_layout()
    plt.show()

我怀疑它与 Normalizer 有关 - 删除以下行时：

svd_train = Normalizer().fit_transform(svd_train)

数据图如下：