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R语言for循环

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基本语法：for （name in expr_1） expr_2

实例操作：

x=array(0,dim=c(4,4)) # 构造四阶矩阵 数值全为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.利用循序进行单位根检验

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)  #构造正太分布，产生20个随机数，服从正太分布
} 

library(tseries)  #导入所需要的函数包

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

 结果如下，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