如何用幾行代碼做特征選擇

from sklearn.feature_selection import RFE
from sklearn.linear_model import LinearRegression
#Load boston housing dataset as an example
X = np.array(train1[feature_use].fillna(-1))[1:train1.size,:]
Y = np.array(train1['target'])[1:train1.size]
#print(X)
#print(Y)
names = feature_use
#use linear regression as the model
lr = LinearRegression()
#rank all features, i.e continue the elimination until the last one
rfe = RFE(lr, n_features_to_select=1)
rfe.fit(X,Y)
print("Features sorted by their score:")
#print(sorted(zip(map(lambda x: round(x, 4), rf.feature_importances_), names),             reverse=True))

sortedlist = sorted(zip(map(lambda x: round(x, 4), rfe.ranking_), names),
             reverse=True)
print(sortedlist)

feature_use = []
for index in sortedlist[len(sortedlist)-70 : ]:
    if index[0]>0:
        feature_use.append(index[1])
print(feature_use)

上面的X為數(shù)據(jù)集的特征集合 Y為標簽集合
在sortlist里對特征的重要性進行了排序

最近做機器學習的一點感悟是，特征的影響遠比模型參數(shù)來的大，特征是現(xiàn)實世界在算法中的倒影。
在特征工程中要對業(yè)務有非常深的理解，強調返璞歸真，刪除無效特征，減少引起干擾的特征。
加特征的過程需要一個一個來，還要多思考這些特征之間的關系，是否是強烈線性相關的。

# random forest select features
'''
from sklearn.ensemble import RandomForestRegressor
import numpy as np
#Load boston housing dataset as an example
X = np.array(train1[feature_use].fillna(-1))[1:train1.size,:]
Y = np.array(train1['target'])[1:train1.size]
print(X)
print(Y)
names = feature_use
rf = RandomForestRegressor()
rf.fit(X, Y)
print("Features sorted by their score:")
print(sorted(zip(map(lambda x: round(x, 4), rf.feature_importances_), names),
             reverse=True))
'''