On 12/07/2010 5:25 PM, Bryan Hanson wrote:
Hello Wise Ones...
I need a clever way around a problem with findInterval. Consider:
vec1 <- 1:10
vec2 <- seq(1, 10, by = 0.1)
x1 <- c(2:3)
a1 <- findInterval(x1, vec1); a1 # example 1
a2 <- findInterval(x1, vec2); a2 # example 2
In the problem I'm working on, vec* may be either integer or numeric, like
vec1 and vec2. I need to remove one or more sections of this vector; for
instance if I ask to remove values 2:3 I want to remove all values between 2
and 3 regardless of the resolution of the data (in my thinking, vec2 is more
dense or has better resolution than vec1). So example 1 above works fine
because the values 2 and 3 are the end points of a range that includes no
values in-between (a1). But, in example 2 the answer is, correctly, also
the end points, but now there are values in between these end points. Hence
a2 doesn't include the indices of the values in-between the end points.
I have looked at cut, but it doesn't quite behave the way I want since if I
set x1 <- c(2:4) I get more intervals than I really want and cleaning it up
will be laborious. I think I can construct the full set of indices I want
with a2[1]:a2[2] but is there a more clever way to do this? I'm thinking
there might be a function out there that I am not aware of.
I'm not sure I understand what you want. If you know x1 will always be
an increasing vector, you could use something like a2[1]:a2[length(a2)]
to select the full range of indices that it covers. If x1 is not
necessarily in increasing order, you'll have to do min(a2):max(a2)
(which might be clearer in any case).
If you're more interested in the range of values in vec*, maybe
range(vec2[min(a2):max(a2)])
will give you want you want.
Duncan Murdoch
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
