如何在R中为向量的特定元素分配名称

Question

My question is: How to assign a name to a specific element of a vector in R, particularly, using the assign(x, value) function.

Normally, to assign a value to a specific element of a vector, I would do as follows:

agent1[2] <- TRUE

But, this is not possible for me , because my (pre-assigned) variables are being called in a for-loop as follows:

for (i in 1:10) {
assign(paste("agent", i, "[2]", sep=""), TRUE)
}

Unfortunately, it seems that the assign function doesn't work for assigning values to specific elements in a vector ! So while the following

for (i in 1:10) {
assign(paste("agent", i, "[2]", sep=""), TRUE)
}

does work to assign the TRUE value to agent1 to agent10, I cannot pick out that it assign the value to only the first (or nth) element in each of the agent vectors.

In a simple case, this can be seen in the following:

a <- 1:4
a[1] <- 2
a[1] == 2           # TRUE

However,

a <- 1:4
assign("a[1]", 2)
a[1] == 2          # FALSE

I'd appreciate any help on how to get around this. Thanks!

Answer 1

We can try

assign('a', `[<-`(a, 1, 2))
a[1]==2
#[1] TRUE

If we need to change the values for a range of index ie the 1st 3 values to 2

assign('a', `[<-`(a, 1:3, 2))
a
#[1] 2 2 2 4