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基于R語言for循環(huán)的替換方案

更新時(shí)間：2021年04月19日 14:38:03 作者：data_momo

這篇文章主要介紹了基于R語言for循環(huán)的替換方案，具有很好的參考價(jià)值，希望對大家有所幫助。一起跟隨小編過來看看吧

R語言中，for循環(huán)運(yùn)行比較慢

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

補(bǔ)充：R語言：for循環(huán)使用小結(jié)

基本結(jié)構(gòu)展示：

vals =c(5,6,7)
for(v in vals){
  print(v)
}
#即把大括號(hào)里的內(nèi)容對vals里的每一個(gè)值都循環(huán)run一遍

實(shí)例展示：

1. paste() 命令是把幾個(gè)字符連接起來

如paste("A","B","C",sep=" ")得到的就是“A B C”，在次基礎(chǔ)上寫如下for loop:

partnumber = c(1,2,5,78)
for(i in partnumber){
 print(paste("participant number",i, sep = " ")) 
}
#就可以得到一串參與者號(hào)碼，根據(jù)上面給定的幾個(gè)值， 從"participant number 1" 到"participant number 8"

2. 雙重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,sep = " "))
}
}
# 先對j循環(huán)，后對i循環(huán)，得到如下結(jié)果
[1] "participant number 1 , institution cancer center"
[1] "participant number 1 , institution RMH"
[1] "participant number 1 , institution Florey"
[1] "participant number 2 , institution cancer center"
[1] "participant number 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"
# 兩個(gè)loop的話，output得放最中心的loop里面，如果只要要第一層loop,就放在靠外一層括號(hào)里面，第二層括號(hào)就保留最后的一個(gè)值

3. 數(shù)據(jù)庫實(shí)例演示

Titanic=read.csv("https://goo.gl/4Gqsnz")  #從網(wǎng)絡(luò)讀取數(shù)據(jù)<0.2, 0.2-0.6還是>0.6。

目的：看不同艙位（Pclass）和不同性別（Sex）的人的生存率是

A<- sort(unique(Pclass))   #sort可以把類別按大小順序排，unique()命令是把分類變量的種類提取出來
B<- sort(unique(Sex))
for(i in A){ 
  for(j in B){
   if(mean(Survived[Pclass==i&Sex==j])<0.2){
    print(paste("for class",i,"sex",j,"mean survival is less than 0.2"))
  } else if (mean(Survived[Pclass==i&Sex==j])>0.6){
    print(paste("for class",i,"sex",j,"mean survival is more than 0.6"))
  } else {
    print(paste("for class",i,"sex",j,"mean survival is between 0.2 and 0.6"))} 
  }  
}

結(jié)果如下：

[1] "for class 1 sex female mean survival is more than 0.6"

[1] "for class 1 sex male mean survival is between 0.2 and 0.6"

[1] "for class 2 sex female mean survival is more than 0.6"

[1] "for class 2 sex male mean survival is less than 0.2"

[1] "for class 3 sex female mean survival is between 0.2 and 0.6"

[1] "for class 3 sex male mean survival is less than 0.2"

補(bǔ)充：R語言for循環(huán)批量生成變量，并且賦值

看代碼~

rm(list=ls())
data <- read.table("MS_identified_information.txt",header = T,sep = "\t",quote="",na.strings = "",row.names = 1,comment.char = "")
name1 <- paste("H1299",sep = "_",c(1:3))
name2 <- paste("Metf",sep = "_",c(1:3))
name3 <- paste("OEMetf",sep = "_",c(1:3))
name <- data.frame(name1,name2,name3)
mean.data=data.frame(row.names(data))
for (i in 1:3){
  tmp <- subset(data,select = as.vector.factor(name[,i])) #篩選特定的樣本
  mean_ <- as.data.frame(apply(tmp, 1, mean)) #行求平均值
  //assign()功能就是對變量進(jìn)行賦值如i=1時(shí)，df1=mean_
  //把三次結(jié)果組合起來
  mean.data <- cbind.data.frame(mean.data,assign(paste("df", i, sep=""), mean_))
  //這里沒有體現(xiàn)出變量，實(shí)際上生成了df1,df2,df3結(jié)果
}
colnames(mean.data) <- c("ID","H1299","Metf","OEMetf")
write.table(mean.data,file="MS_mean.xls",row.names = FALSE,sep = "\t",na="")

以上為個(gè)人經(jīng)驗(yàn)，希望能給大家一個(gè)參考，也希望大家多多支持腳本之家。如有錯(cuò)誤或未考慮完全的地方，望不吝賜教。

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