在 R 编程中计算矩阵或数组的每一列的平均值 - colMeans()函数
R 语言中的colMeans()
函数用于计算矩阵或数组的每一列的平均值。
Syntax: colMeans(x, dims = 1)
Parameters:
x: array of two or more dimensions, containing numeric, complex, integer or logical values, or a numeric data frame
dims: integer value, which dimensions are regarded as ‘columns’ to sum over. It is over dimensions 1:dims.
示例 1:
# R program to illustrate
# colMeans function
# Initializing a matrix with
# 3 rows and 3 columns
x <- matrix(rep(1:9), 3, 3)
# Getting matrix representation
x
# Calling the colMeans() function
colMeans(x)
输出:
[, 1] [, 2] [, 3]
[1, ] 1 4 7
[2, ] 2 5 8
[3, ] 3 6 9
[1] 2 5 8
示例 2:
# R program to illustrate
# colMeans function
# Initializing a 3D array
x <- array(1:12, c(2, 3, 3))
# Getting the array representation
x
# Calling the colMeans() function
# for dims = 1, x[, 1, 1], x[, 2, 1], x[, 3, 1],
# x[, 1, 2] ... are columns
colMeans(x, dims = 1)
# for dims = 2, x[,,1], x[,,2], x[,,3]
# are columns
colMeans(x, dims = 2)
输出:
,, 1
[, 1] [, 2] [, 3]
[1, ] 1 3 5
[2, ] 2 4 6,, 2
[, 1] [, 2] [, 3]
[1, ] 7 9 11
[2, ] 8 10 12,, 3
[, 1] [, 2] [, 3]
[1, ] 1 3 5
[2, ] 2 4 6
[, 1] [, 2] [, 3]
[1, ] 1.5 7.5 1.5
[2, ] 3.5 9.5 3.5
[3, ] 5.5 11.5 5.5
[1] 3.5 9.5 3.5