CODEWITHSUNDEEP
rvectorna
Tpellirn
Tpellirn

Reputation: 796

How to count NA in head of vector?

x=c(NA, 2, -3, NA, -5, 5, -7, -8, -9, -10, NA, -2, 2, -14, -15, NA, -17, 2, NA, -20)

I would like to select the first 10 values that are not NA. so I do:

head(x[!is.na(x)], 10)

Now I want to know how many NA were ignored:

sum(is.na(head(x[is.na(x)], 10)))
# [1] 5

which is not correct: it should be 3

Upvotes: 0

Views: 93

Answers (2)

akrun
akrun

Reputation: 887088

We need logicla vector on the subset of actual vector and not on the NA only data

sum(is.na(head(x, 10)))
#[1] 3

head(x[is.na(x)], 10)
#[1] NA NA NA NA NA

gives only NAs as we are subsetting the NA elements

Update

Based on the logic in comments, one way is

i1 <- !is.na(x)
i1[i1] <- seq_along(i1[i1])
sum(is.na(head(x, which(i1 == 10))))

Upvotes: 3

FloSchmo
FloSchmo

Reputation: 748

This should do it:

sum(is.na(head(x, which(cumsum(!is.na(x)) == 10))))

The cumsum of the logical vector given by !is.na gives us the index of the tenth non-NA number, which is the input we want for the head function (because we want all values of until we get to the tenth non-NA value).

Upvotes: 2

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