> grades<-read.table("D:/ProgramData/test1.txt",sep="\t")
> grades
      V1    V2   V3    V4   V5    V6    V7
1   编号  1.00  2.0  3.00  4.0  5.00  6.00
2  身高m  1.75  1.8  1.65  1.9  1.74  1.91
3 体重kg 60.00 72.0 57.00 90.0 95.00 72.00
> data1<-as.matrix(grades)
> data1
     V1       V2      V3     V4      V5     V6      V7     
[1,] "编号"   " 1.00" " 2.0" " 3.00" " 4.0" " 5.00" " 6.00"
[2,] "身高m"  " 1.75" " 1.8" " 1.65" " 1.9" " 1.74" " 1.91"
[3,] "体重kg" "60.00" "72.0" "57.00" "90.0" "95.00" "72.00"
> data2<-as.numeric(data1[2,2:7])
> data2
[1] 1.75 1.80 1.65 1.90 1.74 1.91
> mean1=mean(data2)
> mean1
[1] 1.791667
> data3<-as.numeric(data1[3,2:7])
> data3
[1] 60 72 57 90 95 72
> mean2=mean(data3)
> mean2
[1] 74.33333

> grades[1,8]="mean"
> grades[2,8]=mean1
> grades[3,8]=mean2
> grades
      V1    V2   V3    V4   V5    V6    V7               V8
1   编号  1.00  2.0  3.00  4.0  5.00  6.00             mean
2  身高m  1.75  1.8  1.65  1.9  1.74  1.91 1.79166666666667
3 体重kg 60.00 72.0 57.00 90.0 95.00 72.00 74.3333333333333

> sd1=sd(data2)
> sd2=sd(data3)
> grades[1,9]="sd"
> grades[2,9]=sd1
> grades[3,9]=sd2
> grades
      V1    V2   V3    V4   V5    V6    V7               V8
1   编号  1.00  2.0  3.00  4.0  5.00  6.00             mean
2  身高m  1.75  1.8  1.65  1.9  1.74  1.91 1.79166666666667
3 体重kg 60.00 72.0 57.00 90.0 95.00 72.00 74.3333333333333
                 V9
1                sd
2 0.100282933077701
3  15.4229266569827

> write.table(grades,"D:/ProgramData/test2.txt")