问题描述
我正在尝试在Iris dateset上选择功能。
我从Feature Selection with Univariate Statistical Tests引用
我正在使用以下几行,我想找出其主要功能:
import pandas
from pandas import read_csv
from numpy import set_printoptions
from sklearn.feature_selection import SelectKBest
from sklearn.feature_selection import f_classif
dataframe = pandas.read_csv("C:\\dateset\\iris.csv"]))
array = dataframe.values
X = array[:,0:4]
Y = array[:,4]
test = SelectKBest(score_func=f_classif,k=2)
fit = test.fit(X,Y)
set_printoptions(precision=2)
arr = fit.scores_
print (arr)
# [ 119.26 47.36 1179.03 959.32]
idx = (-arr).argsort()[:2]
print (idx)
# [2 3]
此外,我如何获得列/变量名(而不是它们的索引)?
解决方法
使用索引,这里可以使用列名,因为选择了前4列:
#first 4 columns
X = array[:,0:4]
cols = dataframe.columns[idx]
如果X
变量的选择不同,则还应按位置DataFrame进行过滤:
#e.g. selected 3. to 7. column
X = array[:,2:6]
cols = dataframe.iloc[:,2:6].columns[idx]
,
import pandas
from pandas import read_csv
from numpy import set_printoptions
from sklearn.feature_selection import SelectKBest
from sklearn.feature_selection import f_classif
dataframe = pandas.read_csv("iris.csv")
array = dataframe.values
X = array[:,0:4]
Y = array[:,4]
test = SelectKBest(score_func=f_classif,k=2)
fit = test.fit(X,Y)
set_printoptions(precision=2)
arr = fit.scores_
idx = (-arr).argsort()[:2]
print (idx)
print (arr)
#names=[dataframe.columns[j] for j in X]
names = dataframe.columns[idx]
print(names)
输出
[2 3]
[ 119.26 47.36 1179.03 959.32]
Index(['petal_length','petal_width'],dtype='object')