R 编程：矩阵的值在哪里得分？

Question

I have a function which returns a list of 3 sub functions as follows:

makeCacheMatrix <- function(x = matrix()) {
inversedMatrix <- NULL
get <- function() x
setMatrix <- function(matrix) inversedMatrix <<- matrix
getMatrix <- function() inversedMatrix
list(get = get,
   setMatrix = setMatrix,
   getMatrix = getMatrix)
}

When I create an object by passing the matrix(1:4, 2, 2) to this function using matrixcal <- makeCacheMatrix(matrix(1:4, 2, 2)) the value of the matrix(1:4, 2, 2) gets stored somewhere. I want to understand where this value is being stored as I do not see it in R studio in the Global environment. Clearly it is being stored somewhere as I can access it later using matrixcal$get()

Thanks in advance!

Answer 1

If you call your function

foo <- makeCacheMatrix(matrix(1:4, 2, 2))

Then look at the object

foo
# $get
# function() x
# <environment: 0x0000021849b5da78>

# $setMatrix
# function(matrix) inversedMatrix <<- matrix
# <environment: 0x0000021849b5da78>

# $getMatrix
# function() inversedMatrix
# <environment: 0x0000021849b5da78>

You'll see that each of the functions has an associated environment (your exact numbers/digits will be different each time you run the function). Your function has created a closure environment to store the variables and functions created.

You can access that environment via

environment(foo$get)

which just gives you the environment object. You can list the contents of that environment with

ls.str(environment(foo$get))
# get : function ()  
# getMatrix : function ()  
# inversedMatrix :  NULL
# setMatrix : function (matrix)  
# x :  int [1:2, 1:2] 1 2 3 4

And there you'll see the original matrix stored in the x value of that environment.