On Jul 8, 2011, at 3:16 PM, Nipesh Bajaj wrote:
Hi there, given a numeric vector, I can select numbers within a
specific range. However presently, I have something related but
different problem. Suppose I have a numeric vector. Now take an
arbitrary number. Goal to to chose a specific subset with a given
length, from that given vector, so that those chosen numbers are
centered around that given constant.
Here is one example:
### My original vector
Vec <- rnorm(1000)
### Now chose some arbitrary number
Number <- 0
### Chose the length of the resulting vector
New.Len <- 10
Now I have to chose 10 numbers from 'Vec' around 'Number'. If my 'Vec'
contains one or more zero then those zero(s) also be selected.
An odd number of values would be easier to "center" around the closest
to zero value. Here is a reduced example that picks out the 7 values
(3 on either side of the closest to zero whose order statistic is
closest to the value closest to zero:
> x <- rnorm(20) # Sorry, forgot to set.seed()
> ?which min
> sort(x)[which.min(abs(sort(x))]
# closest to zero is the 9th value in sort(x)
> sort(x)[(which.min(abs(sort(x)))-3):(which.min(abs(sort(x)))+3)]
[1] -0.15579551 -0.05612874 -0.04493361 -0.01619026 0.07456498
0.38984324
[7] 0.41794156
--
David Winsemius, MD
West Hartford, CT
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