如何在管道内使用 t-SNE

Question

如何在管道中使用t-SNE？ 我已经设法在没有流水线的情况下成功运行t-SNE 并在其上运行分类算法。 我是否需要编写一个可以在返回数据帧的管道中调用的自定义方法，或者它是如何工作的？

# How I used t-SNE
%%time

from sklearn.manifold import TSNE
X_std = StandardScaler().fit_transform(dfListingsFeature_classification)
ts = TSNE()
X_tsne = ts.fit_transform(X_std)

print(X_tsne.shape)
feature_list = []
for i in range(1,X_tsne.shape[1]+1):
    feature_list .append("TSNE" + str(i))
    
df_new = pd.DataFrame(X_tsne, columns= feature_list )

df_new['label'] = y
#df_new.head()

X = df_new.drop(columns=['label'])
y = df_new['label']
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.3, random_state=1, stratify=y) 
#X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.3, random_state=1) 
rfc= RandomForestClassifier()

# Train Decision Tree Classifer
rfc= rfc.fit(X_train,y_train)

#Predict the response for test dataset
y_pred = rfc.predict(X_test)

我想用什么

# How could I use TSNE() inside the the pipeline? 
%%time
steps = [('standardscaler', StandardScaler()),
         ('tsne', TSNE()),
         ('rfc', RandomForestClassifier())]

pipeline = Pipeline(steps) 

X_train, X_test, y_train, y_test = train_test_split(X,y,test_size=0.2, random_state=30)


parameteres = {'rfc__max_depth':[1,2,3,4,5,6,7,8,9,10,11,12],
               'rfc__criterion':['gini', 'entropy']}

grid = GridSearchCV(pipeline, param_grid=parameteres, cv=5)
                 
grid.fit(X_train, y_train)
                    
print("score = %3.2f" %(grid.score(X_test,y_test)))
print('Training set score: ' + str(grid.score(X_train,y_train)))
print('Test set score: ' + str(grid.score(X_test,y_test)))
print(grid.best_params_)

y_pred = grid.predict(X_test)

print("Accuracy:",metrics.accuracy_score(y_test, y_pred))
print("Precison:",metrics.precision_score(y_test, y_pred))
print("Recall:",metrics.recall_score(y_test, y_pred))

[OUT] TypeError: All intermediate steps should be transformers and implement fit and transform or be the string 'passthrough' 'TSNE()' (type <class 'sklearn.manifold._t_sne.TSNE'>) doesn't

我应该构建自定义方法还是如何构建？如果是这样，它应该是什么样子？

class TestTSNE(BaseEstimator, TransformerMixin):
  def __init__(self):
    # don't know

  def fit(self, X, y = None):
    X_std = StandardScaler().fit_transform(dfListingsFeature_classification)
    ts = TSNE()
    X_tsne = ts.fit_transform(X_std)
    return self
    

  def transform(self, X, y = None):
    feature_list = []
    for i in range(1,shelf.X_tsne.shape[1]+1):
        feature_list .append("TSNE" + str(i))
    
    df_new = pd.DataFrame(X_tsne, columns= feature_list )

    df_new['label'] = y
    #df_new.head()

    X = df_new.drop(columns=['label'])
    y = df_new['label']
    return X, y
...
steps = [('standardscaler', StandardScaler()),
         ('testTSNE', TestTSNE()),
         ('rfc', RandomForestClassifier())]

pipeline = Pipeline(steps) 

Answer 1

我认为您误解了管道的使用。来自help page：

带有最终估计器的转换管道。

依次应用变换列表和最终估计器。 管道的中间步骤必须是“转换”，即它们 必须实现 fit 和 transform 方法。仅最终估计器 需要实现fit

所以这意味着如果您的管道是：

steps = [('standardscaler', StandardScaler()),
         ('tsne', TSNE()),
         ('rfc', RandomForestClassifier())]

您将首先将标准缩放器应用于您的特征，然后使用 tsne 转换结果，然后将其传递给分类器。我认为训练 tsne 输出没有多大意义。

如果你真的想锁定管道，那么你需要将 tsne 的结果存储为一个属性，然后只返回特征，按原样训练，以便分类器对其进行处理。

类似

from sklearn.base import BaseEstimator, TransformerMixin
from sklearn.manifold import TSNE
from sklearn.datasets import make_classification

class TestTSNE(BaseEstimator, TransformerMixin):
    def __init__(self,n_components,random_state=None,method='exact'):
        self.n_components = n_components
        self.method = method
        self.random_state = random_state

    def fit(self, X, y = None):
        ts = TSNE(n_components = self.n_components,
        method = self.method, random_state = self.random_state)
        self.X_tsne = ts.fit_transform(X)
        return self

    def transform(self, X, y = None):
        return X

然后：

steps = [('standardscaler', StandardScaler()),
         ('testTSNE', TestTSNE(2)),
         ('rfc', RandomForestClassifier())]

pipeline = Pipeline(steps)
X,y = make_classification()
pipeline.fit(X,y)

您可以像这样检索您的 tsne：

pd.DataFrame(pipeline.steps[1][1].X_tsne)


            0          1
0  -38.756626  -4.693253
1   46.516308  53.633842
2   49.107910  16.482645
3   18.306377   9.432504
4   33.551056 -27.441383
..        ...        ...
95 -31.337574 -16.913471
96 -57.918224 -39.959976
97  55.282658  37.582535
98  66.425125  19.717241
99 -50.692646  11.545088