CODEWITHSUNDEEP
r
user7905871
user7905871

Reputation:

How to use stopifnot with a list in R

Suppose I have a list of vectors. Suppose further that I would like to have a condition based on their length. That is, I would like my function return an error if the lengths of these vectors are not equal.

For example,

x <- c(1:4) y <- c(1:5) z <- c(1:4) k <- list(x, y, z)

I would like to check that their lengths are equal.

stopifnot(length(k[[1]]) == length (k[[2]]) == length(k[[3]]))

How could I generalize this code and make it works for an arbitrary number of elements of the list?

Upvotes: 1

Views: 710

Answers (1)

akrun
akrun

Reputation: 887168

We can use lengths with unique

stopifnot(length(unique(lengths(k)))==1)

Error: length(unique(lengths(k))) == 1 is not TRUE

The lengths will get the length of each of the vector in the list as a vector, get the unique and check if the length is equal to 1. If it is not i.e. stopifnot, give an error

Upvotes: 2

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