python实现的四种抽样⽅法
2.代码实现random python
⽆放回抽样：随机抽样（RandomSampling）和系统抽样(SystematicSampling)。有放回抽样：随机抽样(RepetitionRandomSampling)。
'''
Sampling archive
@author: Garvin Li
'''
import random
def loadDataSet(fileName):      #general function to parse tab -delimited floats    dataMat = []                #assume last column is target value
fr = open(fileName)
for line adlines():
curLine = line.strip().split('\t')
#        fltLine = map(float,curLine) #map all elements to float()
dataMat.append(curLine)
return dataMat
def RandomSampling(dataMat,number):
try:
slice = random.sample(dataMat, number)
return slice
except:
print 'sample larger than population'
def RepetitionRandomSampling(dataMat,number):
sample=[]
for i in range(number):
sample.append(dataMat[random.randint(0,len(dataMat)-1)])
return sample
def SystematicSampling(dataMat,number):
length=len(dataMat)
k=length/number
sample=[]
i=0
if k>0 :
while len(sample)!=number:
sample.append(dataMat[0+i*k])
i+=1
return sample
else :
return RandomSampling(dataMat,number)
if __name__=='__main__':
dataMat=loadDataSet('/Users/hakuri/')
#    print RandomSampling(dataMat,7)
#    RepetitionSampling(dataMat,4)
print SystematicSampling(dataMat,9)

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