---

title: “R example”
author:

• cnliutz
  documentclass: ctexart
  keywords:
• 中文
• R Markdown
  output:
  rticles::ctex:
  fig_caption: yes
  number_sections: yes
  toc: yes

---

数据输入与创建数据框

#C()系列的创建
scores <- c(61,66,90,88,100)
scores

#data.frame 创建数据框
points <- data.frame(
     labels=c("Low","Mid","High"),
     ubound = c(0.674,1.64,2.33),
     lbound = c(0,0.6,1.64)
 )
points
#edit data.frame--表格方式输入数据
score <- data.frame()
score <- edit(score)
#plot
#plot(cars)
#-------------
# scan() 输入数据（数字）
x <-scan()
x
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数据框列求和方法

widgets <- c(179,153,183,153,154)
gadgets <- c(167,193,190,161,181)
thingys <- c(182,166,170,171,186)
daily.prod <- data.frame(widgets,gadgets,thingys,row.names = c('Mon','Tue','Wed','Thu','Fri'))
rbind(daily.prod,Total=colSums(daily.prod))
cbind(daily.prod,Totol=rowSums(daily.prod))

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digits小数位控制

pi
options(digits = 15)
print(pi,digits = 4)  #4位数字
print(100*pi,digits = 4)
cat(pi,"\n")
cat(format(pi,digits = 4),"\n") #4位数字
pnorm(-3:3)
print(pnorm(-3:3),digits = 3)

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输出到文件

#cat使用
#cat("The answer is",answer,file = "filename",append = TRUE)
#cat(data,file = "filename",append = TRUE)
#sink（）使用
#sink("filename")   #屏幕输出被写入文件
    #    ...other session work...
    #source("script.R")
#sink() #停止写入文件，输出到屏幕

#文件列表，目录列表
list.files()
#list.dirs()

#write 把数据写入文件
##write(x,"filename")
#write.csv(data,file = "filename",row.names = T)

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读取数据

# records <- read.fwf("",widths = c(w1,w2,w3,...,w)) #固定宽度的数据格式w-宽度
# dfram <- read.table("data.txt",header=TRUE,sep = ":")
# tbl <- read.csv("filename",header=FALSE)
# tbl <- read.table("http://www.example.com/download/data.txt")  #直接读取网络数据
# 
# save(mydata,file = "mydata.RData")  # 存入
# load("mydata.RData")                # 读出

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不同自由的的t分布图

#pdf("t-distribution.pdf")
par(mfrow=c(2,2))
#opar=par(no.readonly = TRUE)
x=seq(-4,4,length.out=100)

par(fig=c(0,1,0,1))
d1=dt(x,2)
d2=dt(x,5)
d3=dt(x,15)
#不同自由度t分布密度曲线画在一张图上 plot和lines结合即可
plot(d1,ylim = c(0,0.4),type="l")
lines(d2,col='red')
lines(d3,col="blue")
#不同自由度t分布密度曲线画在不同的图上 
plot(x,dt(x,1),type = "l",ylim = c(0,0.5))
plot(x,dt(x,3),type = "l",ylim = c(0,0.5))
plot(x,dt(x,5),type = "l",ylim = c(0,0.5))
plot(x,dt(x,10),type = "l",ylim = c(0,0.5))
plot(x,dt(x,30),type = "l",ylim = c(0,0.5))
#dev.off()

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Cluster聚类分析

means <- sample(c(-3,0,3),replace = T)
x <- rnorm(99,mean = means)
d <- dist(x)
hc <- hclust(d)
plot(hc,hang=-1)
clust <- cutree(hc,k=3)
plot(x~factor(clust),main = "Class Mean")
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几个R函数 list which apply lapply sapply scan cat file

list()列表

findwords <- function(tf){     #tf short for:text file
  txt <- scan(tf,"")           #读取文本文件tf内容，空格间隔的英文内容，汉字不适用
  #print(txt)                   #输出文本列表
  wl <- list()                 #创建word（单词）列表list --wl
  for (i in 1:length(txt)){    # 循环读取txt内单词
    wrd <- txt[i]
    wl[[wrd]] <- c(wl[[wrd]],i)  # wl[[wrd]是个单词位置，把位置向量存起来
  }
  return(wl)
}
#orders the output of findwords() by word frequwncy
freqwl <- function(wordlist){
  freqs <- sapply(wordlist,length)
  return(wordlist[order(freqs)])   #order()按位次排序，sort() 按值排序
}

x <- findwords("tf") 
#print(x)

# names(x)     #显示列表标签名，提取x中的单词
# unlisted(x)  #获取列表的值
# unname(x)    #去掉列表元素名
#sort(names(x)) #列表标签名（单词)排序
#提取词频较高的10%单词作图
#----------------------------
snyt <- freqwl(x)
#print(snyt)
nword <- length(snyt)
#class(nword)
freqs <- sapply(snyt[round(0.9*nword):nword],length)
barplot(freqs)

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列表应用lapply（） & sapply（）

lapply(list(1:6,20:36),median) #输出中位数1:6，20:36列表
sapply(list(1:6,20:36),median) #输出中位数1:6，20:36矩阵
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which()

# which函数
# 1. 返回满足条件的向量下标
cy <- c(1,4,3,7,NA)
cy
which(cy>3)   #返回下标
cy[which(cy>3)]   #返回下标对应的值

# 2.数组中使用
ay <- array(rep(c(4,6,2,1,3,7),2),dim=c(2,3,2))
ay
which(ay>6)
which(ay>6,arr.ind=TRUE)
ay[which(ay>6,arr.ind=TRUE)]
which(ay>6,arr.ind=TRUE,useNames=F)
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数据框中使用

studentID <- c(1,2,3,4,5,6)
gender <- c('M','F','M','M','F','F')
math <- c(40,60,70,60,90,60)
English <- c(98,56,78,93,79,78)
Chinese <- c(86,54,78,90,78,54)
data <- data.frame(studentID,gender,math,English,Chinese,stringsAsFactors = F)
data

which(data[,5]==78)
#挑选语文成绩为78的学生
data[which(data[,5]==78),]
#原文链接：https://blog.csdn.net/chongbaikaishi/article/details/115765282
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画饼pie图

# 数据准备
info = c(1, 2, 4, 8)
# 命名
names = c("Google", "Runoob", "Taobao", "Weibo")
# 涂色（可选）
cols = c("#ED1C24","#22B14C","#FFC90E","#3f48CC")
# 计算百分比
piepercent = paste(round(100*info/sum(info)), "%")
# 绘图
pie(info, labels=piepercent, main = "网站分析", col=cols)
# 添加颜色样本（图例）标注
legend("topright", names, cex=0.8, fill=cols)
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绘制气泡图 bibole

attach(mtcars)
r <- sqrt(disp/pi)
symbols(wt, mpg, circle=r, inches=0.30,
        fg="white", bg="lightblue",
        main="Bubble Plot with point size proportional to displacement",
        ylab="Miles Per Gallon",
        xlab="Weight of Car (lbs/1000)")
text(wt, mpg, rownames(mtcars), cex=0.6)
detach(mtcars)
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scan and cat

rm(list=ls())
# x <- scan("")    #键盘输入数据x
# y <- scan("")    #键盘输入数据y
kids <- c("Tom","jime","cat","peter")
age <- c(23,14,26,25)
d <- data.frame(kids,age)
d
write.table(d,'kids.txt')
#getwd()
kids <- scan(file = "kids.txt",what = "") #读取文件中数据，what=‘’ 字符，默认读取实数。
kids
#scan&cat 配合file()使用
f <- file("kids",'w')
cat("12 23 56",f,append = TRUE) #向文件中追加写入
close(f)

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得到要打开的文件名

f <- choose.files()
print(f)
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