向R中的矩阵添加列和行

所以我想做两个矩阵的点积，即使它们有不同的大小。问题是，如何将所有0的行和列附加到较小的矩阵中，使其与较大的矩阵大小相同

---

例如，如果我有一个2x2矩阵和一个4x4矩阵，我想看看在R中是否有一种方法来编码所有0的2行和2列的相加。有人能帮忙吗？

假设你从两个矩阵开始

m1

和

m2

，其中较大的是

m1

m1 <- matrix(1, 4, 4)
m2 <- matrix(1, 2, 2)

---

m1可能不是最优雅的方式，但我做了一个类似的任务，就是先水平添加填充矩阵，然后垂直添加填充矩阵，以完成缺少的部分，使其可组装。下面是一个函数和一个示例：

set.seed(1)
a <- matrix(rnorm(8), nrow=2, ncol=4)
b <- matrix(rnorm(10), nrow=5, ncol=2)

#> a
#           [,1]       [,2]       [,3]      [,4]
#[1,] -0.6264538 -0.8356286  0.3295078 0.4874291
#[2,]  0.1836433  1.5952808 -0.8204684 0.7383247
#> b
#           [,1]        [,2]
#[1,]  0.5757814 -2.21469989
#[2,] -0.3053884  1.12493092
#[3,]  1.5117812 -0.04493361
#[4,]  0.3898432 -0.01619026
#[5,] -0.6212406  0.94383621

# Here is a function that adds empty rows and columns of 0s to matrices x and y to make them comformable
# Two matrices x and y, and repeated fill element which is by default 0s
filler <- function(x, y, fill = 0){
    # Block of x to add horizontally before vertical block
    horizontal.x = matrix(fill,
        ncol=ifelse(ncol(x) > ncol(y), 0, ncol(y) - ncol(x)),
        nrow=nrow(x)
    )
    # Block of y to add horizontally before vertical block
    horizontal.y = matrix(fill,
        ncol=ifelse(ncol(x) > ncol(y), ncol(x) - ncol(y), 0),
        nrow=nrow(y)
    )
    # Vertical block of x to add after the horizontal block
    vertical.x = matrix(fill,
        ncol=ncol(x) + ncol(horizontal.x),
        nrow=ifelse(nrow(x) > nrow(y), 0, nrow(y) - nrow(x))
    )
    # Vertical block of y to add after the horizontal block
    vertical.y = matrix(fill,
        ncol=ncol(y) + ncol(horizontal.y),
        nrow=ifelse(nrow(x) > nrow(y), nrow(x) - nrow(y), 0)
    )
    # Bind the blocks together and return both within a list
    x <- rbind(cbind(x, horizontal.x), vertical.x)
    y <- rbind(cbind(y, horizontal.y), vertical.y)
    list(x, y)
}

filler(a, b)
filler(b, a)
filler(b, t(a))

#> filler(a, b)
#[[1]]
#           [,1]       [,2]       [,3]      [,4]
#[1,] -0.6264538 -0.8356286  0.3295078 0.4874291
#[2,]  0.1836433  1.5952808 -0.8204684 0.7383247
#[3,]  0.0000000  0.0000000  0.0000000 0.0000000
#[4,]  0.0000000  0.0000000  0.0000000 0.0000000
#[5,]  0.0000000  0.0000000  0.0000000 0.0000000
#
#[[2]]
#           [,1]        [,2] [,3] [,4]
#[1,]  0.5757814 -2.21469989    0    0
#[2,] -0.3053884  1.12493092    0    0
#[3,]  1.5117812 -0.04493361    0    0
#[4,]  0.3898432 -0.01619026    0    0
#[5,] -0.6212406  0.94383621    0    0
#
#> filler(b, a)
#[[1]]
#           [,1]        [,2] [,3] [,4]
#[1,]  0.5757814 -2.21469989    0    0
#[2,] -0.3053884  1.12493092    0    0
#[3,]  1.5117812 -0.04493361    0    0
#[4,]  0.3898432 -0.01619026    0    0
#[5,] -0.6212406  0.94383621    0    0
#
#[[2]]
#           [,1]       [,2]       [,3]      [,4]
#[1,] -0.6264538 -0.8356286  0.3295078 0.4874291
#[2,]  0.1836433  1.5952808 -0.8204684 0.7383247
#[3,]  0.0000000  0.0000000  0.0000000 0.0000000
#[4,]  0.0000000  0.0000000  0.0000000 0.0000000
#[5,]  0.0000000  0.0000000  0.0000000 0.0000000
#
#> filler(b, t(a))
#[[1]]
#           [,1]        [,2]
#[1,]  0.5757814 -2.21469989
#[2,] -0.3053884  1.12493092
#[3,]  1.5117812 -0.04493361
#[4,]  0.3898432 -0.01619026
#[5,] -0.6212406  0.94383621
#
#[[2]]
#           [,1]       [,2]
#[1,] -0.6264538  0.1836433
#[2,] -0.8356286  1.5952808
#[3,]  0.3295078 -0.8204684
#[4,]  0.4874291  0.7383247
#[5,]  0.0000000  0.0000000


ex <- filler(b, t(a))
# This is now defined
ex[[1]] %*% t(ex[[2]])

set.seed（1）
a b
#           [,1]        [,2]
#[1,]  0.5757814 -2.21469989
#[2,] -0.3053884  1.12493092
#[3,]  1.5117812 -0.04493361
#[4,]  0.3898432 -0.01619026
#[5,] -0.6212406  0.94383621
#这是一个函数，它将0的空行和空列添加到矩阵x和y中，以使它们可组合
#两个矩阵x和y，以及重复填充元素（默认为0s）
填料ncol（y），0，ncol（y）-ncol（x）），
nrow=nrow（x）
)
#要在垂直块之前水平添加的y块
水平。y=矩阵（填充，
ncol=ifelse（ncol（x）>ncol（y），ncol（x）-ncol（y），0），
nrow=nrow（y）
)
#要在水平块之后添加的x垂直块
垂直。x=矩阵（填充，
ncol=ncol（x）+ncol（水平x），
nrow=ifelse（nrow（x）>nrow（y），0，nrow（y）-nrow（x））
)
#在水平块之后添加y的垂直块
垂直。y=矩阵（填充，
ncol=ncol（y）+ncol（水平y），
nrow=ifelse（nrow（x）>nrow（y），nrow（x）-nrow（y），0）
)
#将块绑定在一起，并在列表中返回这两个块
x填料（b、a）
#[[1]]
#           [,1]        [,2] [,3] [,4]
#[1,]  0.5757814 -2.21469989    0    0
#[2,] -0.3053884  1.12493092    0    0
#[3,]  1.5117812 -0.04493361    0    0
#[4,]  0.3898432 -0.01619026    0    0
#[5,] -0.6212406  0.94383621    0    0
#
#[[2]]
#           [,1]       [,2]       [,3]      [,4]
#[1,] -0.6264538 -0.8356286  0.3295078 0.4874291
#[2,]  0.1836433  1.5952808 -0.8204684 0.7383247
#[3,]  0.0000000  0.0000000  0.0000000 0.0000000
#[4,]  0.0000000  0.0000000  0.0000000 0.0000000
#[5,]  0.0000000  0.0000000  0.0000000 0.0000000
#
#>填料（b、t（a））
#[[1]]
#           [,1]        [,2]
#[1,]  0.5757814 -2.21469989
#[2,] -0.3053884  1.12493092
#[3,]  1.5117812 -0.04493361
#[4,]  0.3898432 -0.01619026
#[5,] -0.6212406  0.94383621
#
#[[2]]
#           [,1]       [,2]
#[1,] -0.6264538  0.1836433
#[2,] -0.8356286  1.5952808
#[3,]  0.3295078 -0.8204684
#[4,]  0.4874291  0.7383247
#[5,]  0.0000000  0.0000000
前任
sameDim <- function(x, size, fill = 0L) {
    rb <- rbind(x, matrix(fill, size[1]-nrow(x), ncol(x)))
    cbind(rb, matrix(fill, nrow(rb), size[2]-ncol(x)))
}
sameDim(m2, dim(m1))
#      [,1] [,2] [,3] [,4]
# [1,]    1    1    0    0
# [2,]    1    1    0    0
# [3,]    0    0    0    0
# [4,]    0    0    0    0

set.seed(1)
a <- matrix(rnorm(8), nrow=2, ncol=4)
b <- matrix(rnorm(10), nrow=5, ncol=2)

#> a
#           [,1]       [,2]       [,3]      [,4]
#[1,] -0.6264538 -0.8356286  0.3295078 0.4874291
#[2,]  0.1836433  1.5952808 -0.8204684 0.7383247
#> b
#           [,1]        [,2]
#[1,]  0.5757814 -2.21469989
#[2,] -0.3053884  1.12493092
#[3,]  1.5117812 -0.04493361
#[4,]  0.3898432 -0.01619026
#[5,] -0.6212406  0.94383621

# Here is a function that adds empty rows and columns of 0s to matrices x and y to make them comformable
# Two matrices x and y, and repeated fill element which is by default 0s
filler <- function(x, y, fill = 0){
    # Block of x to add horizontally before vertical block
    horizontal.x = matrix(fill,
        ncol=ifelse(ncol(x) > ncol(y), 0, ncol(y) - ncol(x)),
        nrow=nrow(x)
    )
    # Block of y to add horizontally before vertical block
    horizontal.y = matrix(fill,
        ncol=ifelse(ncol(x) > ncol(y), ncol(x) - ncol(y), 0),
        nrow=nrow(y)
    )
    # Vertical block of x to add after the horizontal block
    vertical.x = matrix(fill,
        ncol=ncol(x) + ncol(horizontal.x),
        nrow=ifelse(nrow(x) > nrow(y), 0, nrow(y) - nrow(x))
    )
    # Vertical block of y to add after the horizontal block
    vertical.y = matrix(fill,
        ncol=ncol(y) + ncol(horizontal.y),
        nrow=ifelse(nrow(x) > nrow(y), nrow(x) - nrow(y), 0)
    )
    # Bind the blocks together and return both within a list
    x <- rbind(cbind(x, horizontal.x), vertical.x)
    y <- rbind(cbind(y, horizontal.y), vertical.y)
    list(x, y)
}

filler(a, b)
filler(b, a)
filler(b, t(a))

#> filler(a, b)
#[[1]]
#           [,1]       [,2]       [,3]      [,4]
#[1,] -0.6264538 -0.8356286  0.3295078 0.4874291
#[2,]  0.1836433  1.5952808 -0.8204684 0.7383247
#[3,]  0.0000000  0.0000000  0.0000000 0.0000000
#[4,]  0.0000000  0.0000000  0.0000000 0.0000000
#[5,]  0.0000000  0.0000000  0.0000000 0.0000000
#
#[[2]]
#           [,1]        [,2] [,3] [,4]
#[1,]  0.5757814 -2.21469989    0    0
#[2,] -0.3053884  1.12493092    0    0
#[3,]  1.5117812 -0.04493361    0    0
#[4,]  0.3898432 -0.01619026    0    0
#[5,] -0.6212406  0.94383621    0    0
#
#> filler(b, a)
#[[1]]
#           [,1]        [,2] [,3] [,4]
#[1,]  0.5757814 -2.21469989    0    0
#[2,] -0.3053884  1.12493092    0    0
#[3,]  1.5117812 -0.04493361    0    0
#[4,]  0.3898432 -0.01619026    0    0
#[5,] -0.6212406  0.94383621    0    0
#
#[[2]]
#           [,1]       [,2]       [,3]      [,4]
#[1,] -0.6264538 -0.8356286  0.3295078 0.4874291
#[2,]  0.1836433  1.5952808 -0.8204684 0.7383247
#[3,]  0.0000000  0.0000000  0.0000000 0.0000000
#[4,]  0.0000000  0.0000000  0.0000000 0.0000000
#[5,]  0.0000000  0.0000000  0.0000000 0.0000000
#
#> filler(b, t(a))
#[[1]]
#           [,1]        [,2]
#[1,]  0.5757814 -2.21469989
#[2,] -0.3053884  1.12493092
#[3,]  1.5117812 -0.04493361
#[4,]  0.3898432 -0.01619026
#[5,] -0.6212406  0.94383621
#
#[[2]]
#           [,1]       [,2]
#[1,] -0.6264538  0.1836433
#[2,] -0.8356286  1.5952808
#[3,]  0.3295078 -0.8204684
#[4,]  0.4874291  0.7383247
#[5,]  0.0000000  0.0000000


ex <- filler(b, t(a))
# This is now defined
ex[[1]] %*% t(ex[[2]])