Question

我正在使用消费者价格指数CPI，为了计算它，我必须将指数矩阵与相应的权重相乘：

grossCPI77_10 <- grossIND1977 %*% weights1910/100 
grossCPI82_10 <- grossIND1982 %*% weights1910/100

当然我更愿意拥有像以下那样的代码：

grossIND1982 <- replicate(20, cbind(1:61))
grossIND1993 <- replicate(20, cbind(1:61))
weights1910_sc <- c(1:20)
grossIND_list <- mget(ls(pattern = "grossIND...."))
totalCPI <- mapply("*", grossIND_list, weights1910_sc)

问题是它给了我一个1200x20的矩阵。我期望一个正常的矩阵（61x20）向量（20x1）乘法，它应该导致20x1向量？你能解释一下我做错了吗？感谢

Answer 1

我不确定我是否理解你问题的所有方面（特别是关于应该是colums的内容，应该是什么行，以及应该以何种顺序应用crossproduct），但我会尝试至少涵盖某些方面。请参阅以下代码中的注释，以了解您所做的和您可能想要的内容。我希望它有所帮助，让我知道这是否是你需要的。

#instead of using mget, I recommend to use a list structure
#otherwise you might capture other variables with similar names
#that you do not want
INDlist <- sapply(c("1990", "1991"), function(x) {

  #this is how to set up a matrix correctly, check `?matrix`
  #I think your combination of cbind and rep did not give you what you wanted
  matrix(rep(1:61, 20), nrow = 61)

}, USE.NAMES = TRUE, simplify = F)

weights <- list(c(1:20))

#the first argument of mapply needs to be a function, in this case of two variables
#the body of the function calculates the cross product
#you feed the arguments (both lists) in the following part of mapply
#I have repeated your weights, but you might assign different weights for each year
res <- mapply(function(x, y) {x %*% y}, INDlist, rep(weights, length(INDlist)))
dim(res)
#[1] 61  2

Answer 2

你的问题的一部分是你没有矩阵而是3D阵列，只有一个单一维度。另一个问题是mapply喜欢尝试将结果组合成一个矩阵，而且常量参数应该通过MoreArgs传递。但实际上，这更适用于lapply。

grossIND1982 <- replicate(20, cbind(1:61))[,1,]
grossIND1993 <- replicate(20, cbind(1:61))[,1,]
weights1910_sc <- c(1:20)
grossIND_list <- mget(ls(pattern = "grossIND...."))
totalCPI <- mapply("*", grossIND_list, MoreArgs=list(e2 = weights1910_sc), SIMPLIFY = FALSE) 


totalCPI <- lapply(grossIND_list, "*",  e2 = weights1910_sc)

列表与矩阵时间总是相同的向量

2 个答案: