2.1.向量生成
(1)用 c（）逐一放到一起，允许重复值
> c(2,5,6,2,9)
[1] 2 5 6 2 9
> c("a","f","md","b")
[1] "a" "f" "md" "b"
(2)连续的数字用冒号“:”
> 1:15
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
(3)有重复的用rep(),有规律的序列用seq(),等差数列随机数用rnorm
> rep("gene",times=15)
[1] "gene" "gene" "gene" "gene" "gene" "gene" "gene" "gene" "gene"
[10] "gene" "gene" "gene" "gene" "gene" "gene"
> seq(from = 3,to = 21,by = 3)#等差数列
[1] 3 6 9 12 15 18 21
> rnorm(n = 5, mean = 3, sd = 5)#正态曲线：平均值+-标准差
[1] 7.564325 -2.151259 5.991248 2.028028 7.973115
#(4)通过组合,产生更为复杂的向量。
> paste0(rep("gene",times=15),1:15)#两个向量一对一连接
[1] "gene1" "gene2" "gene3" "gene4" "gene5" "gene6" "gene7"
[8] "gene8" "gene9" "gene10" "gene11" "gene12" "gene13" "gene14"
[15] "gene15"
练习2: 向量生成
1.将两种不同类型的数据用c()组合在一起，看输出结果
> c(1,"a")
[1] "1" "a"
> c(T,F,0)
[1] 1 0 0
> c(T,"a")
[1] "TRUE" "a"
2.生成1到30之间所有4的倍数，答案是
#4，8，12，16，20，24，28
> seq(from = 4,to = 30,by = 4)
[1] 4 8 12 16 20 24 28
3.生成sample4，sample8，sample12…sample28
> # 提示：paste0
> paste0(rep("sample",times = 7),
+ seq(from = 4,to = 30,by = 4))
[1] "sample4" "sample8" "sample12" "sample16" "sample20" "sample24"
[7] "sample28"
2.2对单个向量进行的操作
(1)赋值给一个变量名
> x = c(1,3,5,6,2) #随意的写法
> x
[1] 1 3 5 6 2
> x <- c(1,3,5,3) #规范的赋值符号Alt➕减号
> x#四个元素
[1] 1 3 5 3
> #赋值+输出同步运行
> x <- c(1,3,5);x#两行命令用分号连接
[1] 1 3 5
> (x <- c(1,3,5))
[1] 1 3 5
(2)简单数学计算
> x+1
[1] 2 4 6
> log(x)
[1] 0.000000 1.098612 1.609438
> sqrt(x)
[1] 1.000000 1.732051 2.236068
> x %% 10 #取整
[1] 1 3 5
> x %/% 3 #取余
[1] 0 1 1
(3)根据某条件进行判断
> x>3
[1] FALSE FALSE TRUE
> x==3
[1] FALSE TRUE FALSE
(4)初级统计
> max(x) #最大值
[1] 5
> min(x) #最小值
[1] 1
> range(x) #max和min极差
[1] 1 5
> which.max(x) #最大值下标#返回的是位置（即下标，索引）
[1] 3
> which.min(x) #最小值下标
[1] 1
> sort(x,decreasing = T)
[1] 5 3 1
> mean(x) #均值
[1] 3
> median(x) #中位数
[1] 3
> var(x) #方差
[1] 4
> sd(x) #标准差
[1] 2
> sum(x) #总和
[1] 9
> length(x) #长度？
[1] 3
> unique(x) #去重复
[1] 1 3 5
> table(x) #重复值统计
x
1 3 5
1 1 1
2.3.对两个向量进行的操作#####
> x = c(1,3,5)
> y = c(3,2,5)
(1)逻辑比较，生成等长的逻辑向量
> x == y
[1] FALSE FALSE TRUE
> x %in% y #x中的每一个元素判断是否在y中，输出逻辑值
[1] FALSE TRUE TRUE
(2)数学计算
> x + y#一一相加
[1] 4 5 10
(3)“连接“
> paste(x,y,sep=":")#注意与paste0的区别，是否可以用sep
[1] "1:3" "3:2" "5:5"
(4)交集、并集、差集
> intersect(x,y)#交集
[1] 3 5
> union(x,y)#并集，，自动去重
[1] 1 3 5 2
> setdiff(x,y)#差集，返回前面那个有的,你有我没有，以第一个为准
[1] 1
> #当两个向量长度不一致
> x == y
[1] FALSE FALSE TRUE
2.4.利用循环补齐简化代码
> paste0(rep("gene",15),1:15)#按tab键，然后选择下一类
[1] "gene1" "gene2" "gene3" "gene4" "gene5" "gene6" "gene7"
[8] "gene8" "gene9" "gene10" "gene11" "gene12" "gene13" "gene14"
[15] "gene15"
> paste0("gene",1:15)#循环补齐原理
[1] "gene1" "gene2" "gene3" "gene4" "gene5" "gene6" "gene7"
[8] "gene8" "gene9" "gene10" "gene11" "gene12" "gene13" "gene14"
[15] "gene15"
> x <- 8:12
> #根据逻辑值取子集
> x[x==10]
[1] 10
> x[x<12]
[1] 8 9 10 11
> x[x %in% c(9,13)]
[1] 9
> #根据位置取子集
> x[4]
[1] 11
> x[2:4]
[1] 9 10 11
> x[c(1,5)]
[1] 8 12
> x[-4]
[1] 8 9 10 12
> x[-(2:4)]
[1] 8 12
2.5.修改向量中的某个/某些元素：取子集+赋值
> x[4] <- 40
> x
[1] 8 9 10 40 12
> x[x>3] <- 3
> x
[1] 3 3 3 3 3
练习3
1.将基因名"ACTR3B","ANLN","BAG1","BCL2","BIRC5","RAB","ABCT","ANF","BAD","BCF","BARC7","BALV"组成一个向量,赋值给x
> x = c("ACTR3B","ANLN","BAG1","BCL2","BIRC5","RAB","ABCT","ANF","BAD","BCF","BARC7","BALV")
2.用函数计算向量长度
> length(x)
[1] 12
3.用向量取子集的方法,选出第1,3,5,7,9,11个基因名。
> seq(1,11,2)
[1] 1 3 5 7 9 11
> x[seq(1,11,2)]
[1] "ACTR3B" "BAG1" "BIRC5" "ABCT" "BAD" "BARC7"
> x[c(1,3,5,7,9)]
[1] "ACTR3B" "BAG1" "BIRC5" "ABCT" "BAD"
4.用向量取子集的方法,选出除倒数第2个以外所有的基因名。
> x[-11]
[1] "ACTR3B" "ANLN" "BAG1" "BCL2" "BIRC5" "RAB" "ABCT"
[8] "ANF" "BAD" "BCF" "BALV"
> length(x)-1#倒数第二个
[1] 11
> x[-(length(x)-1)]#反向取值
[1] "ACTR3B" "ANLN" "BAG1" "BCL2" "BIRC5" "RAB" "ABCT"
[8] "ANF" "BAD" "BCF" "BALV"
5.用向量取子集的方法,选出出在c("ANLN", "BCL2","TP53")中有的基因名。
> # 提示：%in%
> y = c("ANLN", "BCL2","TP53")
> x %in% y
[1] FALSE TRUE FALSE TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
[12] FALSE
> x[x %in% y]
[1] "ANLN" "BCL2"
6.修改第6个基因名为"a"并查看是否成功
> x[6] <- "a"
7.生成100个随机数: rnorm(n=100,mean=0,sd=18)
> z = rnorm(n=100,mean=0,sd=18)
> #将小于-2的统一改为-2,将大于2的统一改为2
> z[z< (-2)] <- -2#加括号shift+9或者空格 不然成了赋值号
> z[z>2] <- 2
>
1.两个不同类型的向量合并在一起会怎么样？
1.两个不同类型的向量合并在一起会怎么样？
2.如何将两个向量合到一起，组成一个长向量？
1.两个不同类型的向量合并在一起会怎么样？
2.如何将两个向量合到一起，组成一个长向量？
3.如何在向量首/尾/中间某位置增加一个元素？