Hi,
During the course of putting together a function I came across some
unexpected behaviour when using seq() and %in%.
I am creating two numeric vectors using seq(), and then using %in% to find
the values in one vector that are in the other. Sometimes all the values
are found, but sometimes a value is not found. It seems that the behaviour
is inconsistent and I don't understand why.
Below are some reproducible examples:
vec1 <- seq(from = 0.1, to = 20, by = 0.1)
vec2 <- seq(from = 2, to = 20, by = 2)
vec1[vec1 %in% vec2]
[1] 2 4 6 8 10 12 14 16 20
The value 18 is not found.
Starting vec1 at 0.2:
vec1 <- seq(from = 0.2, to = 20, by = 0.1)
vec2 <- seq(from = 2, to = 20, by = 2)
vec1[vec1 %in% vec2]
[1] 2 4 8 10 12 14 16 18 20
Now the value 6 is not found.
Starting vec1 at 0.5:
vec1 <- seq(from = 0.5, to = 20, by = 0.1)
vec2 <- seq(from = 2, to = 20, by = 2)
vec1[vec1 %in% vec2]
[1] 2 4 6 8 10 12 14 16 18 20
Now all the values are found.
Can someone please explain what is happening? Why should the starting value
of vec1 make a difference?
Thanks
Finlay
R version info:
platform x86_64-pc-linux-gnu
arch x86_64
os linux-gnu
system x86_64, linux-gnu
version.string R version 3.0.1 (2013-05-16)
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