<- c(1, 2, -8, 9, 16)
my_vector[2:4]
#矩阵
#矩阵行列命名,默认先排列
cells <- c(1, 36, 24, 12)
row_names <- c(“R1...″, “R2″)
col_names <- c(“C1″, “C2″)
my_matrix1 <- matrix(cells, nrow=2, ncol=2, dimnames=list(row_names..."Improved", "Excellent", "Poor")
patientdata <- data.frame(patientID, age, diabetes, status)
#选取数据框中的元素...levels=c("male","female")) #有序性因子
sex1 = factor(c(1,0,0),levels=c(0,1),labels=c("male","female")) #构建因子的简单表示