获取SelectKBest函数python的功能名称

时间:2017-10-25 08:27:59

标签: python selection

我从sklearn实现了SelectKBest,我希望得到K最佳col的名称,而不仅仅是每个col的值。

我需要做什么?

我的代码:

X_new = SelectKBest(chi2, k=2).fit_transform(X, y)

X_new.shape

X_new是一个numpy.ndarray,它有k col但没有col名称。

3 个答案:

答案 0 :(得分:7)

您可以获取所选功能的索引

示例1

from sklearn.datasets import load_iris
from sklearn.feature_selection import SelectKBest
from sklearn.feature_selection import chi2

iris = load_iris()
X, y = iris.data, iris.target

selector = SelectKBest(chi2, k=2)
selector.fit(X, y)

X_new = selector.transform(X)
X_new.shape
print(selector.get_support(indices=True))

现在,如果您真的想获得列的实际名称,我们需要使用pandas

示例2

from sklearn.datasets import load_iris
from sklearn.feature_selection import SelectKBest
from sklearn.feature_selection import chi2
import pandas as pd

iris = load_iris()
X = pd.DataFrame(iris.data, columns=iris.feature_names)
y = pd.DataFrame(iris.target)

selector = SelectKBest(chi2, k=2)
selector.fit(X, y)

X_new = selector.transform(X)
print(X_new.shape)

X.columns[selector.get_support(indices=True)]

# 1st way to get the list
vector_names = list(X.columns[selector.get_support(indices=True)])
print(vector_names)

#2nd way
X.columns[selector.get_support(indices=True)].tolist()

结果

Index([u'petal length (cm)', u'petal width (cm)'], dtype='object')

['petal length (cm)', 'petal width (cm)']

['petal length (cm)', 'petal width (cm)']

答案 1 :(得分:3)

model = SelectKBest(f_classif,k = 8).fit(X,Y)

<强> Selected_feature_names = X.columns [model.get_support()]

答案 2 :(得分:2)

model=SelectKBest(k=5) model.fit(X,y)

print(model.get_params)