Tim Pigden Tim Pigden - 1 year ago 81
R Question

R: How to pass values from a vector as args to gsub

gsub requires string arguments. But I'm want to process a whole array of string replacements. My sample code is as follows, but doesn't work

pairs <- c(c("a", "b"), c("e", "f"))
gsub("a", "b", "age")
#[1] "bge"

p1 <- pairs[1][1]
#[1] "a"

p2 <- pairs[1][2]

gsub(p1, p2, "age")
#[1] NA

I'm sure this is fundamental thing about difference between vectors and strings but I don't know how to solve it. Apologies for what is doubtless a duplicate question but I've searched a lot of false leads in trying to google it

So with comment and answer from below I now understand:
Not really getting the "everything is a vector" I was making a false mental model that c("a", "b") turned characters into a vector of characters.
By extension I was thinking c(c("a", "b"), c("e", "f")) was creating a vector of vectors
But c("a", "b") is actually combining 2 single-element vectors into a single 2-element vector and by extension c(c("a", "b"), c("e", "f")) actually combines two 2-element vectors into a 4-element vector.
So matrices indeed is what I should have been working with in the first place.
Thanks guys!

Answer Source

Although you have pairs as vector of character vectors. Ultimately if you check pairs it gives as

#[1] "a" "b" "e" "f"

So you can use them with single indexing

p1 <- pairs[1]
p2 <- pairs[2]

gsub(p1, p2, "age")
#[1] "bge"
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