在 R 编程中获取列数矩阵 - col()函数

R 语言中的col()函数用于获取一个矩阵，该矩阵包含作为参数传递给它的矩阵的列数。

Syntax: col(x, as.factor=FALSE)

Parameters:
x: matrix
as.factor: a logical value indicating whether the value should be returned as a factor of column labels (created if necessary) rather than as numbers

示例 1：

# R program to illustrate
# col function
  
# Initializing a matrix with
# 2 rows and 2 columns
x <- matrix(c(1, 2, 3, 4), 2, 2)
  
# Getting the matrix representation
x
  
# Calling the col() function
col(x)

输出：

[, 1] [, 2]
[1, ]    1    3
[2, ]    2    4
     [, 1] [, 2]
[1, ]    1    2
[2, ]    1    2

示例 2：

# R program to illustrate
# col function
  
# Initializing a matrix with
# 3 rows and 3 columns
x <- matrix(rep(1:9), 3, 3)
  
# Getting the matrix representation
x
  
# Calling the col() function
col(x)

输出：

[, 1] [, 2] [, 3]
[1, ]    1    4    7
[2, ]    2    5    8
[3, ]    3    6    9

     [, 1] [, 2] [, 3]
[1, ]    1    2    3
[2, ]    1    2    3
[3, ]    1    2    3