R语言day7:函数的高级运用（1）

rm(list = ls())
if(!require(stringr))install.packages('stringr')
library(stringr)

x <- "The birch canoe slid on the smooth planks."
x

## [1] "The birch canoe slid on the smooth planks."

### 1.检测字符串长度
str_length(x) #一个引号为一个字符串

## [1] 42

length(x)

## [1] 1

### 2.字符串拆分
str_split(x," ")

## [[1]]
## [1] "The"     "birch"   "canoe"   "slid"    "on"     
## [6] "the"     "smooth"  "planks."

class(str_split(x," "))

## [1] "list"

x2 = str_split(x," ")[[1]];x2 #列表取子集

## [1] "The"     "birch"   "canoe"   "slid"    "on"     
## [6] "the"     "smooth"  "planks."

y = c("jimmy 150","nicker 140","tony 152")
str_split(y," ")

## [[1]]
## [1] "jimmy" "150"  
## 
## [[2]]
## [1] "nicker" "140"   
## 
## [[3]]
## [1] "tony" "152"

str_split(y," ",simplify = T) #将拆分结果简化 #返回了一个matrix数据结构

##      [,1]     [,2] 
## [1,] "jimmy"  "150"
## [2,] "nicker" "140"
## [3,] "tony"   "152"

#matrix只能有一种数据类型，不能只改其中一列数据类型
#只有数据框可以修改其中一列数据类型

### 3.按位置提取字符串
str_sub(x,5,9)#从x字符串的第5位到第9位截取

## [1] "birch"

### 4.字符检测
str_detect(x2,"h") #哪一个字符含有h

## [1]  TRUE  TRUE FALSE FALSE FALSE  TRUE  TRUE FALSE

str_starts(x2,"T") #是否T开头

## [1]  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE

str_ends(x2,"e") #是否以e结尾

## [1]  TRUE FALSE  TRUE FALSE FALSE  TRUE FALSE FALSE

### 5.字符串替换
x2

## [1] "The"     "birch"   "canoe"   "slid"    "on"     
## [6] "the"     "smooth"  "planks."

str_replace(x2,"o","A") #只替换第一个出现o为A

## [1] "The"     "birch"   "canAe"   "slid"    "An"     
## [6] "the"     "smAoth"  "planks."

str_replace_all(x2,"o","A")

## [1] "The"     "birch"   "canAe"   "slid"    "An"     
## [6] "the"     "smAAth"  "planks."

str_replace_all(x2,"o｜e","A")

## [1] "The"     "birch"   "canoe"   "slid"    "on"     
## [6] "the"     "smooth"  "planks."

### 6.字符删除
x

## [1] "The birch canoe slid on the smooth planks."

str_remove(x," ") #删除第一个空格

## [1] "Thebirch canoe slid on the smooth planks."

str_remove_all(x," ") #删除所有空格

## [1] "Thebirchcanoeslidonthesmoothplanks."

test <- iris[c(1:2,51:52,101:102),]
rownames(test) =NULL # 去掉行名，NULL是“什么都没有”
test

##   Sepal.Length Sepal.Width Petal.Length Petal.Width
## 1          5.1         3.5          1.4         0.2
## 2          4.9         3.0          1.4         0.2
## 3          7.0         3.2          4.7         1.4
## 4          6.4         3.2          4.5         1.5
## 5          6.3         3.3          6.0         2.5
## 6          5.8         2.7          5.1         1.9
##      Species
## 1     setosa
## 2     setosa
## 3 versicolor
## 4 versicolor
## 5  virginica
## 6  virginica

# arrange，数据框按照某一列排序

library(dplyr)
arrange(test, Sepal.Length) #根据指定列将所有行从小到大排序

##   Sepal.Length Sepal.Width Petal.Length Petal.Width
## 1          4.9         3.0          1.4         0.2
## 2          5.1         3.5          1.4         0.2
## 3          5.8         2.7          5.1         1.9
## 4          6.3         3.3          6.0         2.5
## 5          6.4         3.2          4.5         1.5
## 6          7.0         3.2          4.7         1.4
##      Species
## 1     setosa
## 2     setosa
## 3  virginica
## 4  virginica
## 5 versicolor
## 6 versicolor

arrange(test, desc(Sepal.Length)) #从大到小

##   Sepal.Length Sepal.Width Petal.Length Petal.Width
## 1          7.0         3.2          4.7         1.4
## 2          6.4         3.2          4.5         1.5
## 3          6.3         3.3          6.0         2.5
## 4          5.8         2.7          5.1         1.9
## 5          5.1         3.5          1.4         0.2
## 6          4.9         3.0          1.4         0.2
##      Species
## 1 versicolor
## 2 versicolor
## 3  virginica
## 4  virginica
## 5     setosa
## 6     setosa

# distinct，数据框按照某一列去重复
distinct(test,Species,.keep_all = T) #留下第一行去掉重复的行

##   Sepal.Length Sepal.Width Petal.Length Petal.Width
## 1          5.1         3.5          1.4         0.2
## 2          7.0         3.2          4.7         1.4
## 3          6.3         3.3          6.0         2.5
##      Species
## 1     setosa
## 2 versicolor
## 3  virginica

# mutate，数据框新增一列
mutate(test, new = Sepal.Length * Sepal.Width)

##   Sepal.Length Sepal.Width Petal.Length Petal.Width
## 1          5.1         3.5          1.4         0.2
## 2          4.9         3.0          1.4         0.2
## 3          7.0         3.2          4.7         1.4
## 4          6.4         3.2          4.5         1.5
## 5          6.3         3.3          6.0         2.5
## 6          5.8         2.7          5.1         1.9
##      Species   new
## 1     setosa 17.85
## 2     setosa 14.70
## 3 versicolor 22.40
## 4 versicolor 20.48
## 5  virginica 20.79
## 6  virginica 15.66

#运行这句代码test需要赋值

# 连续的步骤

# 1.多次赋值，产生多个中间的变量
x1 = select(iris,-5)
x2 = as.matrix(x1)
x3 = head(x2,50) #取前50行
pheatmap::pheatmap(x3)

# 2. 嵌套，代码不易读
pheatmap::pheatmap(head(as.matrix(select(iris,-5)),50))

# 3.管道符号传递，简洁明了
iris %>% #%>% #cmd+shift+m
  select(-5) %>%
  as.matrix() %>%
  head(50) %>% 
  pheatmap::pheatmap()

rm(list = ls())

i = -1
if (i<0) print('up')

## [1] "up"

if (i>0) print('up')

#理解下面代码
if(!require(tidyr)) install.packages('tidyr')
#读取下一级文件夹里的文件 read.csv(xiaolizhenbang/x.csv)
#读取上一级read.csv(../dalizhenbang/x.csv)

i =1
if (i>0){ #()一个逻辑值
  print('+')
} else {
  print("-")
}

## [1] "+"

i = 1
ifelse(i>0,"+","-")

## [1] "+"

x = rnorm(3)
x

## [1] -0.9283129 -0.1291495 -0.7929700

ifelse(x>0,"+","-")

## [1] "-" "-" "-"

samples = c("tumor1","tumor2","tumor3","normal1","normal2","normal3")
k1 = str_detect(samples,"tumor");k1

## [1]  TRUE  TRUE  TRUE FALSE FALSE FALSE

ifelse(k1,"tumor","normal")

## [1] "tumor"  "tumor"  "tumor"  "normal" "normal" "normal"

k2 = str_detect(samples,"normal");k2

## [1] FALSE FALSE FALSE  TRUE  TRUE  TRUE

ifelse(k2,"normal","tumor")

## [1] "tumor"  "tumor"  "tumor"  "normal" "normal" "normal"

i = 0
if (i>0){
  print('+')
} else if (i==0) {
  print('0')
} else if (i< 0){
  print('-')
}

## [1] "0"

ifelse(i>0,"+",ifelse(i<0,"-","0"))

## [1] "0"

for( i in 1:4){
  print(i)
}

## [1] 1
## [1] 2
## [1] 3
## [1] 4

#批量画图
par(mfrow = c(2,2))
for(i in 1:4){
  plot(iris[,i],col = iris[,5])
}

#批量装包
pks = c("tidyr","dplyr","stringr")
for(g in pks){
  if(!require(g,character.only = T))
    install.packages(g,ask = F,update = F)
}