如何在列表中存储循环遍历列表R

想想我有一个简单的问题，但到目前为止我无法找到我的错误。我想创建一个有32名参与者的单一淘汰赛。要做到这一点，我创建4组8名球员，现在是想建立一个在对决for循环，并将它们存储到一个列表，但它不工作，我想:(如何在列表中存储循环遍历列表R

>groups 
      A  B  C  D 
    1 Player1 Player9 Player17 Player25 
    2 Player2 Player10 Player18 Player26 
    3 Player3 Player11 Player19 Player27 
    4 Player4 Player12 Player20 Player28 
    5 Player5 Player13 Player21 Player29 
    6 Player6 Player14 Player22 Player30 
    7 Player7 Player15 Player23 Player31 
    8 Player8 Player16 Player24 Player32

现在我想存储他们在他们的小组对有一个容易获得计算后再夺道具应该是这样的第一组

>teams.group.A <- matrix(groups$A,nrow = 2,ncol = 4) 
>teams.group.A 
    [,1]  [,2]  [,3]  [,4]  
[1,] "Player1" "Player3" "Player5" "Player7" 
[2,] "Player2" "Player4" "Player6" "Player8"

我对环路的想法是：

groupnames <- colnames(groups) 

mylist <- list() 
for(i in groupnames){ 
    mylist[[i]] <- matrix(groups$i,nrow = 2,ncol = 4) 
} 
mylist

我得到错误，“数据”必须是矢量类型？

Thx，如果你能帮助我这里！

来源

2017-07-11 Paul Hoffmann

你需要'list'作为输出吗？或'data.frame'好吗？ – CPak

只是为了解释错误：如果您使用$ i，R将不会评估i。这意味着它会直接在数据框中查找一个名为i的变量，该变量不存在。如果你使用组[，我]它的工作原理，因为在这种情况下，我被它的当前值取代。在任何情况下，解决方案@Val发布是一种方式，因为循环在R中不如在其他语言中更可取。 – friep

假设你groups变量是一个数据框，你可以很容易地使用lapply，你会得到一个不错的命名列表的结果：

# generate data 
players <- paste0('Player',1:32) 
grps <- data.frame(A=players[1:8],B=players[9:16],C=players[17:24],D=players[25:32]) 


#smoother version as suggested by P Lapointe: 
mylist <- lapply(grps,matrix,nrow=2) 

# more verbose 
# mylist <- lapply(grps,function(x) matrix(x,ncol = 4)) 


# output 

> mylist 
$A 
    [,1]  [,2]  [,3]  [,4]  
[1,] "Player1" "Player3" "Player5" "Player7" 
[2,] "Player2" "Player4" "Player6" "Player8" 

$B 
    [,1]  [,2]  [,3]  [,4]  
[1,] "Player9" "Player11" "Player13" "Player15" 
[2,] "Player10" "Player12" "Player14" "Player16" 

$C 
    [,1]  [,2]  [,3]  [,4]  
[1,] "Player17" "Player19" "Player21" "Player23" 
[2,] "Player18" "Player20" "Player22" "Player24" 

$D 
    [,1]  [,2]  [,3]  [,4]  
[1,] "Player25" "Player27" "Player29" "Player31" 
[2,] "Player26" "Player28" "Player30" "Player32"

要使其重新成为一个单一的数据框，您可以使用do.call(cbind,mylist) ：

> do.call(cbind,mylist) 
    [,1]  [,2]  [,3]  [,4]  [,5]  [,6]  [,7]  [,8]  [,9]  [,10]  [,11]  
[1,] "Player1" "Player3" "Player5" "Player7" "Player9" "Player11" "Player13" "Player15" "Player17" "Player19" "Player21" 
[2,] "Player2" "Player4" "Player6" "Player8" "Player10" "Player12" "Player14" "Player16" "Player18" "Player20" "Player22" 
    [,12]  [,13]  [,14]  [,15]  [,16]  
[1,] "Player23" "Player25" "Player27" "Player29" "Player31" 
[2,] "Player24" "Player26" "Player28" "Player30" "Player32"

来源

2017-07-11 14:48:44 Val

您可以将参数传递给像这样的函数：'lapply（grps，matrix，nrow = 2）' –

太棒了！永远学习。 – Val

你不能索引在使用$循环i，因为i是character。试试这个

for (i in groupnames) { 
    mylist[[i]] = matrix(groups[[i]], nrow=2, ncol=4) 
}

来源

2017-07-11 14:51:54 juan

如何在列表中存储循环遍历列表R

回答

相关问题