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1、1．在某中学随机抽取某年纪30名学生，测量其身高（X1），体重（X2），胸围（X3）和坐高（X4），数据如表所示，试对着30名中学生身体四项指标数据做主成分分析，写出分析结果，并画出主成分的碎石图X1X2X3X4X1X2X3X41148417278161523573792139347176171494782793160497786181453570774149366779191604774875159458086201564478856142316676211514273827153437683221473873788150437779231
2、57396880915142778024147306575101393168742515748808811140296474261513674801216147788427144366876131584978832814130677614140336777291393268731513731667330148387078答案：#输入数据#student<-data.frame(X1=c(148,139,160,149,159,142,153,150,151,139,140,161,158,140,137,152,149,145,160,156
3、,151,147,157,147,157,151,144,141,139,148),X2=c(41,34,49,36,45,31,43,43,42,31,29,47,49,33,31,35,47,35,47,44,42,38,39,30,48,36,36,30,32,38),X3=c(72,71,77,67,80,66,76,77,77,68,64,78,78,67,66,73,82,70,74,78,73,73,68,65,80,74,68,67,68,70),X4=c(78,76,86,79,86,76,83,79,80,74,74,84
4、,83,77,73,79,79,77,87,85,82,78,80,75,88,80,76,76,73,78))#主成分分析#student.pr<-princomp(student,cor=TRUE)summary(student.pr)Importanceofcomponents:Comp.1Comp.2Comp.3Comp.4Standarddeviation1.88178050.559806360.281795940.25711844ProportionofVariance0.88527450.078345790.019852240.
5、01652747CumulativeProportion0.88527450.963620290.983472531.00000000Standarddeviation行表示的是主成分的标准差。ProportionofVariance行表示的是方差的贡献率。CumulativeProportion行表示的是方差的累积贡献率。#碎石图#screeplot(student.pr,type="lines")2．已知ribosomeassembly过程基因集合数目为55，背景基因数目为20814，现有197个基因的集合，其中有7个基因属于riboso
6、meassembly过程，请用fisherexacttest判断该基因集合是否显著富集到ribosomeassembly过程。答案：据题目可以得到下表GenelistGenomelistInannogroup748Notinannogroup19020569##code##count<-matrix(c(7,190,48,20569),nrow=2)count[,1][,2][1,]748[2,]19020569fisher.test(count)Fisher'sExactTestforCountDatadata:countp-value=8
7、.45e-07alternativehypothesis:trueoddsratioisnotequalto195percentconfidenceinterval:5.94600335.691581sampleestimates:oddsratio15.77913因p_value<0.05,所以认为该基因集合显著富集到ribosomeassembly过程。
