CODEWITHSUNDEEP
rregextrim
sir_chocolate_soup
sir_chocolate_soup

Reputation: 449

what is going on with my trimws?

I was fiddling around in text cleaning when I ran into an interesting occurrence.

Reproducible Code:

trimws(list(c("this is an outrante", " hahaha", " ")))

Output: 

[1] "c(\"this is an outrante\", \" hahaha\", \" \")"

I've checked out the trimws documentation and it doesn't go into any specifics besides the fact that it expects a character vector, and in my case, I've supplied with a list of a list of character vectors. I know I can use lapply to easily solve this, but what I want to understand is what is going on with my trimws as is?

Upvotes: 1

Views: 699

Answers (1)

akrun
akrun

Reputation: 887541

The trimws would be directly applied to vector and not on a list.

According to ?trimws documentation, the usage is

trimws(x, which = c("both", "left", "right"))

where

x- a character vector

It is not clear why the vector is wrapped in a list

trimws(c("this is an outrante", " hahaha", " "))

If it really needs to be in a list, then use one of the functions that goes into the list elements and apply the trimws

lapply(list(c("this is an outrante", " hahaha", " ")), trimws)

Also, note that the OP's list is a list of length 1, which can be converted back to a vector either by [[1]] or unlist (more general)

trimws(list(c("this is an outrante", " hahaha", " "))[[1]])

Regarding why a function behaves this, it is supposed to have an input argument as a vector. The behavior is similar for other functions that expect a vector, for e.g.

paste(list(c("this is an outrante", " hahaha", " ")))
as.character(list(c("this is an outrante", " hahaha", " ")))

If we check the trimws function, it is calling regex sub which requires a vector

mysub <- function(re, x) sub(re, "", x, perl = TRUE) 
mysub("^[ \t\r\n]+", list(c("this is an outrante", " hahaha", " ")))
#[1] "c(\"this is an outrante\", \" hahaha\", \" \")"

Pass it a vector

mysub("^[ \t\r\n]+", c("this is an outrante", " hahaha", " "))
#[1] "this is an outrante" "hahaha"              ""

Upvotes: 3

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