生信课程note-2
原创
title: "noteH"
output: html_document
date: "2023-02-06"
class 2
2.1数据类型转换的优先顺序：
数值型会转变成字符型
c(1,"a") "1" "a"
逻辑型会转变成字符型
逻辑型会变成数值型
2.2 对单个向量进行的操作
（1）赋值
x <- c(1,3,5,1) #规范的赋值符号 Alt+减号 是等号的意思
x回车可以看x里面是什么东西
x = c(1,3,5,1) #随意的写法
#赋值+输出一起实现
x <- c(1,3,5,1);x
(x <- c(1,3,5,1))
注：
建议/不建议使用的变量名:
yes：x,y,z,A,B no: c "x"
yes：jimmy,bala no:seq,limma
yes：x1,bala1 no:1x，1bala
yes：x_1 no: x 1
yes：x.1 no: x-1 , x+1
yes：gp1_number no: 芭芭拉
(2)简单数学计算
x+1
log(x)
sqrt(x)
(3)根据某条件进行判断,生成逻辑型向量
x>3
x==3
(4)初级统计
max(x) #最大值
min(x) #最小值
mean(x) #均值
median(x) #中位数
var(x) #方差
sd(x) #标准差
sum(x) #总和
length(x) #长度
unique(x) #去重复 从左到右第二次出现才叫重复。
duplicated(x) #对应元素是否重复 重复是T
table(x) #重复值统计
sort(x) 默认排序是从小到大
sort(x,decreasing = F) 其实是升序
sort(x,decreasing = T) 是降序
2.3对两个向量的操作
(1)比较运算，生成等长的逻辑向量
x == y
y == x
(2)数学计算
x + y
(3)连接
paste(x,y,sep=",")
paste与paste0的区别
paste(x,y)
paste0(x,y)
paste(x,y,sep = "")
paste(x,y,sep = ",")
#当两个向量长度不一致
x = c(1,3,5,6,2)
y = c(3,2,5)
x == y #判断是否相等
会发生循环补齐--看ppt
会发生循环补齐的是x==y;paste(x,y);x+y
#利用循环补齐简化代码
paste0(rep("x",3),1:3)
paste0("x",1:3)
(4)交集、并集、差集
intersect(x,y) 系统会去重复
union(x,y)
setdiff(x,y) x里有y里没有
setdiff(y,x) y有x没有
重点： %in%
x %in% y #x的每个元素在y中存在吗
y %in% x #y的每个元素在x中存在吗
2.4.向量筛选(取子集)--
x <- 8:12
#根据逻辑值取子集
xx==10
xx<12
xx %in% c(9,13)
#根据位置取子集
x4
x2:4
xc(1,5) 取出第一个和第五个
x-4 去掉第四个
x-(2:4)
2.5.修改向量中的某个/某些元素：
取子集+赋值
#改一个元素
x4 <- 40
x
#改多个元素
xc(1,5) <- c(80,20)
x
2.6 简单向量作图
k1 = rnorm(12);k1
k2 = rep(c("a","b","c","d"),each = 3);k2
plot(k1)
boxplot(k1~k2) #
实操：
R Markdown
# 1.生成1到15之间所有偶数
seq(from = 1,to = 15,by = 2)`
## [1] 1 3 5 7 9 11 13 15
seq(from = 2,to = 15,by = 2)
## [1] 2 4 6 8 10 12 14
# 2.生成向量，内容为："student2" "student4" "student6" "student8" "student10" "student12"
# "student14"
# 提示：paste0
paste0(rep("student",times = 7),seq(from = 2, to = 15,by = 2))
## [1] "student2" "student4" "student6" "student8" "student10" "student12" "student14"
# 3.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(TRUE,"a")## [1] "TRUE" "a"c(1,TRUE)## [1] 1 1# 4.用函数计算向量g的长度
load("gands.Rdata")
length(g)## [1] 100# 5.筛选出向量g中下标为偶数的基因名。
seq(2,100,2)## [1] 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42
## [22] 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84
## [43] 86 88 90 92 94 96 98 100g[seq(2,100,2)]## [1] "CRAMP1L" "PRSS8" "CRAMP1L" "SLCO1C1" "COMMD1" "CCT4"
## [7] "RAB7A" "ZDHHC16" "MYL12B" "SNRPE" "ZNF586" "GGT7"
## [13] "RAB7A" "AFG3L2" "AC104581.1" "MPP2" "ATP2A2" "SNRPE"
## [19] "PRSS8" "ZNF461" "CECR5" "CLEC17A" "ATG10" "ATG10"
## [25] "SLC25A25" "KRTAP4-3" "SLCO1C1" "GGT7" "GSTP1" "UBAC1"
## [31] "NYNRIN" "MYL12B" "KCND1" "RGPD3" "C10orf128" "SLC30A9"
## [37] "GGT7" "TUBA4A" "KLHDC8A" "HBP1" "MARC2" "LCP1"
## [43] "OR2D3" "LIPE" "LIPE" "CANX" "ATP6V1B2" "MARC2"
## [49] "LCP1" "HOOK2"# 6.向量g中有多少个元素在向量s中存在(要求用函数计算出具体个数)？将这些元素筛选出来
# 提示：%in%
table(g %in% s)##
## FALSE TRUE
## 37 63g[g %in% s]## [1] "GFM2" "SLCO1C1" "NYNRIN" "COMMD1" "COMMD1"
## [6] "AC017081.1" "RAB7A" "CASKIN2" "GGT7" "SNRPE"
## [11] "RGPD3" "ZNF586" "COMMD1" "GGT7" "URB1"
## [16] "RAB7A" "MPP2" "AFG3L2" "URB1" "AC104581.1"
## [21] "MPP2" "SNRPE" "ARHGAP1" "ZNF461" "OR2D3"
## [26] "CECR5" "SPDL1" "CLEC17A" "ZNF461" "ATG10"
## [31] "ATG10" "ATG10" "SLC25A25" "SLC30A9" "SLCO1C1"
## [36] "GGT7" "CASKIN2" "GSTP1" "MPP2" "NYNRIN"
## [41] "INTS12" "MPP2" "RGPD3" "RGPD3" "SLC30A9"
## [46] "C10orf128" "HBD" "SLC30A9" "GGT7" "HEPH"
## [51] "RP5-1021I20.4" "KLHDC8A" "HBD" "ZNF586" "CECR5"
## [56] "OR2D3" "LIPE" "INTS12" "LIPE" "SPDL1"
## [61] "SLCO1C1" "GGT7" "CECR5"
# 7.生成10个随机数: rnorm(n=10,mean=0,sd=18)，用向量取子集的方法，取出其中小于-2的值
z = rnorm(n=10,mean=0,sd=18)
z[z<(-2)]
## [1] -4.657298 -8.565170 -18.576409 -2.250447引自生信技能树
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原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。
如有侵权，请联系 cloudcommunity@tencent.com 删除。