基于R语言for循环的替换方案

r语言中，for循环运行比较慢

for(i in 1:1000){print(i^2)}

补充：r语言：for循环使用小结

基本结构展示：

vals =c(5,6,7)for(v in vals){  print(v)}#即把大括号里的内容对vals里的每一个值都循环run一遍

实例展示：

1. paste() 命令是把几个字符连接起来

如paste(“a”,”b”,”c”,p=” “)得到的就是“a b c”，在次基础上写如下for loop:

partnumber = c(1,2,5,78)for(i in partnumber){ print(paste("participant number",i, p = " ")) }#就可以得到一串参与者号码，根据上面给定的几个值， 从"participant number 1" 到"participant number 8" 

2. 双重loop

partnumber = c(1,2,5,78)institution =c("cancer center", "rmh", "florey")for(i in partnumber){  for(j in institution){  print(paste("participant number",i,", institution",j,p = " "))}}# 先对j循环，后对i循环，得到如下结果[1] "participant number 1 , institution cancer center"[1] "participant number 1 , institution rmh"[1] "participant number 1 , institution florey"[1] "part电子商务发展现状icipant number 2 , institution cancer center"[1] "participant nu张槐乾mber 2 , institution rmh"[1] "participant number 2 , institution florey"[1] "participant number 5 , institution cancer center"[1] "participant number 5 , institution rmh"[1] "participant number 5 , institution florey"[1] "participant number 78 , institution cancer center"[1] "participant number 78 , institution rmh"[1] "participant number 78 , institution florey"# 两个loop的话，output得放最中心的loop里面，如果只要要第一层loop,就放在靠外一层括号里面，第二层括号就保留最后的一个值

3. 数据库实例演示

titanic=read.csv("https://goo.gl/4gqsnz")  #从网络读取数据<0.2, 0.2-0.6还是>0.6。

目的：看不同舱位（pclass）和不同性别（x）的人的生存率是

a<- sort(unique(pclass))   #sort可以把类别按大小顺序排，unique()命令是把分类变量的种类提取出来b<- sort(unique(x))for(i in a){   for(j in b){   if(mean(survived[pclass==i&x==j])<0.2){    print(paste("for class",i,"x",j,"读高铁学校好吗mean surviv承翰学校al is less than 0.2"))  } el if (mean(survived[pclass==i&x==j])>0.6){    print(paste("for class",i,"x",j,"mean survival is more than 0.6"))  } el {    print(paste("for class",i,"x",j,"mean survival is between 0.2 and 0.6"))}   }  }

结果如下：

[1] “for class 1 x female mean survival is more than 0.6”

[1] “for class 1 x male mean survival is between 0.2 and 0.6”

[1] “for class 2 x female mean survival is more than 0.6”

[1] “for class 2 x male mean survival is less than 0.2”

[1] “for class 3 x female mean survival is between 0.2 and 0.6”

[1] “for class 3 x male mean survival is less than 0.2”

补充：r语言for循环批量生成变量，并且赋值

看代码~

rm(list=ls())data <- read.table("ms_identified_information.txt",header = t,p = "\t",quote="",na.strings = "",row.names = 1,comment.char = "")name1 <- paste("h1299",p = "_",c(1:3)给老师送什么礼物合适)name2 <- paste("metf",p = "_",c(1:3))name3 <- paste("oemetf",p = "_",c(1:3))name <- data.frame(name1,name2,name3)mean.data=data.frame(row.names(data))for (i in 1:3){  tmp <- subt(data,lect = as.vector.factor(name[,i])) #筛选特定的样本  mean_ <- as.data.frame(apply(tmp, 1, mean)) #行求平均值  //assign()功能就是对变量进行赋值如i=1时，df1=mean_  //把三次结果组合起来  mean.data <- cbind.data.frame(mean.data,assign(paste("df", i, p=""), mean_))  //这里没有体现出变量，实际上生成了df1,df2,df3结果}colnames(mean.data) <- c("id","h1299","metf","oemetf")write.table(mean.data,file="ms_mean.xls",row.names = fal,p = "\t",na="")

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