forループ内にforループの配列を追加する

Question

forループに配列を追加しようとしました。 しかし、繰り返しごとに私のループは上書きされます。 どうすれば解決できますか？

rnormRdn <- matrix() #init empty matrix set.seed(1234) 
set.seed(1234) 
    for(i in 1:3){ 
    rnormRdn <- matrix(rnorm(n = 4), nrow = 2, ncol = 2) 
    print("New random matrix that should be appended is:") 
    print(rnormRdn) 
    appendMat <- array(data = rnormRdn, dim = c(2,2,i)) 
    print("New random matrix not correctly apended on after first iteration:") 
    print(appendMat) 
    i <- i+1 
    } 

結果：最後の繰り返しで

[1] "New random matrix that should be appended is:" 
      [,1]  [,2] 
[1,] -1.2070657 1.084441 
[2,] 0.2774292 -2.345698 
[1] "New random matrix not correctly apended on after first iteration:" 
, , 1 

      [,1]  [,2] 
[1,] -1.2070657 1.084441 
[2,] 0.2774292 -2.345698 

[1] "New random matrix that should be appended is:" 
      [,1]  [,2] 
[1,] 0.4291247 -0.5747400 
[2,] 0.5060559 -0.5466319 
[1] "New random matrix not correctly apended on after first iteration:" 
, , 1 

      [,1]  [,2] 
[1,] 0.4291247 -0.5747400 
[2,] 0.5060559 -0.5466319 

, , 2 

      [,1]  [,2] 
[1,] 0.4291247 -0.5747400 
[2,] 0.5060559 -0.5466319 

[1] "New random matrix that should be appended is:" 
      [,1]  [,2] 
[1,] -0.5644520 -0.4771927 
[2,] -0.8900378 -0.9983864 
[1] "New random matrix not correctly apended on after first iteration:" 
, , 1 

      [,1]  [,2] 
[1,] -0.5644520 -0.4771927 
[2,] -0.8900378 -0.9983864 

, , 2 

      [,1]  [,2] 
[1,] -0.5644520 -0.4771927 
[2,] -0.8900378 -0.9983864 

, , 3 

      [,1]  [,2] 
[1,] -0.5644520 -0.4771927 
[2,] -0.8900378 -0.9983864 

期待される結果：

[1] "New random matrix not correctly apended on after first iteration:" 
, , 1 

      [,1]  [,2] 
[1,] -1.2070657 1.084441 
[2,] 0.2774292 -2.345698 

, , 2 

      [,1]  [,2] 
[1,] 0.4291247 -0.5747400 
[2,] 0.5060559 -0.5466319 

, , 3 

      [,1]  [,2] 
[1,] -0.5644520 -0.4771927 
[2,] -0.8900378 -0.9983864 

Answer 1

次のことを試してみてください。

set.seed(1234) 
# initialize array, giving dimensions 
myArray <- array(0, dim=c(2,2,3)) 

for(i in 1:3){ 
    rnormRdn <- matrix(rnorm(n = 4), nrow = 2, ncol = 2) 
    print("New random matrix that should be appended is:") 
    print(rnormRdn) 
    myArray[,,i] <- rnormRdn 
    print("New random matrix not correctly apended on after first iteration:") 
    print(myArray) 
} 

アレイのサイズを事前に知っていれば、2行目と同じようにスペースをあらかじめ割り当てておく方がずっと効率的です。