R: NaNs produced

Question

I have a time series in R Studio. Now I want to calculate the log() of this series. I tried the following:

i <- (x-y) 
ii <- log(i)

But

Answer 1

Use the test to subset your original vector with the values that produce NaN:

> i <- c(9,8,4,5,-7,1,6,-1,8,4,Inf,-Inf,NA)
> i[which(is.nan(log(i)))]
[1]   -7   -1 -Inf
Warning message:
In log(i) : NaNs produced

Here you see that -7, -1, and -Inf produced NaN.

Note that log(NA) is not NaN, its NA, which is a different sort of not-numberness.

Answer 2

As I said in my comment, to know which observation generated the NaN, you can use function which:

i <- c(9,8,4,5,7,1,6,-1,8,4)
which(is.nan(log(i))) # 8