R語言for循環

基本語法：for （name in expr_1） expr_2

實例操作：

1.構造矩陣

x=array(0,dim=c(4,4)) # 構造四階矩陣 數值全為0
for (i in 1:4){
    for (j in 1:4){
        x[i,j]=1/(i+j+1)
  }
    }
print(x)

         [,1]      [,2]      [,3]      [,4]
[1,] 0.3333333 0.2500000 0.2000000 0.1666667
[2,] 0.2500000 0.2000000 0.1666667 0.1428571
[3,] 0.2000000 0.1666667 0.1428571 0.1250000
[4,] 0.1666667 0.1428571 0.1250000 0.1111111

2.利用循序進行單位根檢驗

nrow=20
ncol=5
A=matrix(nrow=nrow,ncol=ncol,data=NA)

for (i in 1:ncol)
{
A[,i]=  rnorm(20, mean=0, sd=1)  #構造正太分布，產生20個隨機數，服從正太分布
} 

library(tseries)  #導入所需要的函數包

for (i in 1:5)
{print(adf.test(A[,i]))}  #AD

 結果如下，很方便.

 Augmented Dickey-Fuller Test

data:  A[, i]
Dickey-Fuller = -2.4773, Lag order = 2, p-value = 0.3905
alternative hypothesis: stationary


        Augmented Dickey-Fuller Test

data:  A[, i]
Dickey-Fuller = -1.8836, Lag order = 2, p-value = 0.6167
alternative hypothesis: stationary


        Augmented Dickey-Fuller Test

data:  A[, i]
Dickey-Fuller = -3.5647, Lag order = 2, p-value = 0.05491
alternative hypothesis: stationary


        Augmented Dickey-Fuller Test

data:  A[, i]
Dickey-Fuller = -2.2957, Lag order = 2, p-value = 0.4597
alternative hypothesis: stationary


        Augmented Dickey-Fuller Test

data:  A[, i]
Dickey-Fuller = -2.2784, Lag order = 2, p-value = 0.4663
alternative hypothesis: stationary

　　

F單位根檢驗