R

[R语言] apply函数

这是一篇关于R语言科学计算的技术文档

Posted by Leung ZhengHua on 2017-11-15

本文总点击量次

最近在使用apply函数，想要往函数FUN里面输入多个参数再调用apply，下面是实验的结果：

apply

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ryan=function(x,y,msg) {
  return(paste0(x,y,msg))
}
ryan(5,6,"-hello")
apply(matrix(1:6,ncol = 1), 1, ryan,y=1:8,msg=c("-GOOD MORING",'-GOOD AFTERNOON','-GOOD NIGHT'))
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     [,1]                [,2]                [,3]                [,4]                [,5]               
[1,] "11-GOOD MORING"    "21-GOOD MORING"    "31-GOOD MORING"    "41-GOOD MORING"    "51-GOOD MORING"   
[2,] "12-GOOD AFTERNOON" "22-GOOD AFTERNOON" "32-GOOD AFTERNOON" "42-GOOD AFTERNOON" "52-GOOD AFTERNOON"
[3,] "13-GOOD NIGHT"     "23-GOOD NIGHT"     "33-GOOD NIGHT"     "43-GOOD NIGHT"     "53-GOOD NIGHT"    
[4,] "14-GOOD MORING"    "24-GOOD MORING"    "34-GOOD MORING"    "44-GOOD MORING"    "54-GOOD MORING"   
[5,] "15-GOOD AFTERNOON" "25-GOOD AFTERNOON" "35-GOOD AFTERNOON" "45-GOOD AFTERNOON" "55-GOOD AFTERNOON"
[6,] "16-GOOD NIGHT"     "26-GOOD NIGHT"     "36-GOOD NIGHT"     "46-GOOD NIGHT"     "56-GOOD NIGHT"    
[7,] "17-GOOD MORING"    "27-GOOD MORING"    "37-GOOD MORING"    "47-GOOD MORING"    "57-GOOD MORING"   
[8,] "18-GOOD AFTERNOON" "28-GOOD AFTERNOON" "38-GOOD AFTERNOON" "48-GOOD AFTERNOON" "58-GOOD AFTERNOON"
     [,6]               
[1,] "61-GOOD MORING"   
[2,] "62-GOOD AFTERNOON"
[3,] "63-GOOD NIGHT"    
[4,] "64-GOOD MORING"   
[5,] "65-GOOD AFTERNOON"
[6,] "66-GOOD NIGHT"    
[7,] "67-GOOD MORING"   
[8,] "68-GOOD AFTERNOON"

可以看到apply把第一个参数识别为x，参数ryan后面，跟着和x长度不同的参数y和msg，可以见到，apply遍历了每组参数下的结果，这正是我们想要的。

但是当ryan中的参数y是矩阵（或者向量）的时候，apply识别不出y是应该按单个元素输入，还是按整块矩阵输入。

比如下面这种：

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ryan=function(x,y,msg) {
  return(paste0(x,sum(y),msg))
}
ryan(5,6:9,c("-hello",', sir'))
apply(matrix(1:6,ncol = 1), 1, ryan,y=1:8,msg=c("-GOOD MORING",'-GOOD AFTERNOON','-GOOD NIGHT'))
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[1] "530-hello" "530, sir" 
     [,1]                 [,2]                 [,3]                
[1,] "136-GOOD MORING"    "236-GOOD MORING"    "336-GOOD MORING"   
[2,] "136-GOOD AFTERNOON" "236-GOOD AFTERNOON" "336-GOOD AFTERNOON"
[3,] "136-GOOD NIGHT"     "236-GOOD NIGHT"     "336-GOOD NIGHT"    
     [,4]                 [,5]                 [,6]                
[1,] "436-GOOD MORING"    "536-GOOD MORING"    "636-GOOD MORING"   
[2,] "436-GOOD AFTERNOON" "536-GOOD AFTERNOON" "636-GOOD AFTERNOON"
[3,] "436-GOOD NIGHT"     "536-GOOD NIGHT"     "636-GOOD NIGHT"

解决办法可以考虑使用嵌套的apply函数

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