R编程中获取对象的列数——ncol()函数

R语言中的ncol()函数用于返回指定矩阵的列数。

Syntax: ncol(x)
Parameters:
x: matrix, vector, array or data frame

示例 1：

Python3

# R program to illustrate
# ncol function
 
# Getting R Biochemical Oxygen Demand Dataset
BOD
 
# Calling ncol() function to
# get the number of columns
ncol(BOD)

Python3

# R program to illustrate
# ncol function
 
# Specifying a matrix
x <- matrix(c(1, 2, 3, 4), 2, 2)
 
# Calling the ncol() function
ncol(x)

输出：

Time demand
1    1    8.3
2    2   10.3
3    3   19.0
4    4   16.0
5    5   15.6
6    7   19.8

[1] 2

示例 2：

Python3

# R program to illustrate
# ncol function
 
# Specifying a matrix
x <- matrix(c(1, 2, 3, 4), 2, 2)
 
# Calling the ncol() function
ncol(x)

输出：

[1] 2