,c(2,3)]
m[2,]
m[,2]
m[2]#第2行,第1列
m[-1,2]
m["R1","C1"]
4.4 矩阵的运算
m+1#矩阵m中每一个元素都加1
colSums(m)#每一列的总和
rowSums...- array(1:24, c(2,3,4), dimnames=list(dim1, dim2, dim3))
六.数据框
数据框的索引
attach(mtcars)# mtcars为内置数据集,使用...2.54)
transform(women, cm = height*2.54)#新增一列,列名为cm
worldphones <- as.data.frame(WorldPhones)
rs rowSums...24,4,6)
c=mtcars
d <- "This is a test list"
mlist <- list(ni=a,hao=b,ya=c,la=d)
7.2 列表索引
mlist[1]#输出的为列表的子集...Mon","Tue","Wed","Thu","Fri","Sat","Sun"))#添加order = TRUE表示有序型变量b
九.NA(未知值) NaN(不存在的值,如0/0) Inf(无穷大或无穷小