如何在R中创建一个空矩阵?

问题描述：

我是R的新手.我想使用cbind用我的for循环的结果填充一个空矩阵.我的问题是，如何消除矩阵第一栏中的NA.我在下面包含了我的代码:

I am new to R. I want to fill in an empty matrix with the results of my for loop using cbind. My question is, how can I eliminate the NAs in the first column of my matrix. I include my code below:

output<-matrix(,15,) ##generate an empty matrix with 15 rows, the first column already filled with NAs, is there any way to leave the first column empty?

for(`enter code here`){
  normF<-`enter code here`
  output<-cbind(output,normF)
}

输出是我期望的矩阵.唯一的问题是它的第一列中填充了NA.如何删除这些NA?

The output is the matrix I expected. The only issue is that its first column is filled with NAs. How can I delete those NAs?

答

matrix的默认值是1列.要明确拥有0列，您需要编写

The default for matrix is to have 1 column. To explicitly have 0 columns, you need to write

matrix(, nrow = 15, ncol = 0)

更好的方法是预分配整个矩阵，然后将其填充

A better way would be to preallocate the entire matrix and then fill it in

mat <- matrix(, nrow = 15, ncol = n.columns)
for(column in 1:n.columns){
  mat[, column] <- vector
}

如何在R中创建一个空矩阵?

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