Repeated Indexing / Sequence Operation

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Hi Everyone,

quick question before the end of the year.

I have soem indices to select data from a bigger sample. I want to select n
days before each index and n days after the index. Any clever way to do it.
A for loop would do but I wanted to know if there is a moreR-friendly way to
approach this
How about this:

SampleWidth <- 5
samples <- (-SampleWidth):SampleWidth
i2 <- c(90, 190, 290)
i3 <- as.vector(outer(samples, i2,  "+"))

Duncan Murdoch
Example
# InitialIndices
i2 = (90, 190, 290)

# Indices I want to end up with
i3 = c(85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 185, 186, 187, 188, 189,
190, 191, 192, 193, 194, 195
285, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295)
# A way to get Final Indices
SampleWidth
i3 = c(i2)
for (j in seq(1, SampleWidth )) {
i3 = c(i3, i2 + j )
  i3 = c(i3, i2 - j )
  }

I tried to tackle this with seq and the apply families but got nowhere

Thanks and Happy New Year

Paolo

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On Fri, Dec 31, 2010 at 1:03 PM, Paolo Rossi
Hi Everyone,

quick question before the end of the year.

I have soem indices to select data from a bigger sample. I want to select n
days before each index and n days after the index. Any clever way to do it.
A for loop would do but I wanted to know if there is a moreR-friendly way to
approach this

Example
# InitialIndices
i2 = (90, 190, 290)

# Indices I want to end up with
i3 = c(85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 185, 186, 187, 188, 189,
190, 191, 192, 193, 194, 195
285, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295)
# A way to get Final Indices
SampleWidth
i3 = c(i2)
for (j in seq(1, SampleWidth )) {
i3 = c(i3, i2 + j )
?i3 = c(i3, i2 - j )
?}
Try this:

n <- 5
c(sapply(i2, function(x) seq(x - n, x + n)))
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com

Hi Everyone,

quick question before the end of the year.

I have soem indices to select data from a bigger sample. I want to select n
days before each index and n days after the index. Any clever way to do it.
For heavy duty applications involving intervals - many intervals, finding 
overlapping intervals, set operations, et cetera, you may want to use the 
IRanges package:

http://www.bioconductor.org/help/bioc-views/release/bioc/html/IRanges.html
A for loop would do but I wanted to know if there is a moreR-friendly way to
approach this

Example
# InitialIndices
i2 = (90, 190, 290)

Like this:
 i2 <- c(90, 190, 290)
as.vector( IRanges( start= i2 - 5, end = i2 + 5 ) )
[1]  85  86  87  88  89  90  91  92  93  94  95 185 186 187 188 189 190 191 192
[20] 193 194 195 285 286 287 288 289 290 291 292 293 294 295

HTH,

Chuck
# Indices I want to end up with
i3 = c(85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 185, 186, 187, 188, 189,
190, 191, 192, 193, 194, 195
285, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295)
# A way to get Final Indices
SampleWidth
i3 = c(i2)
for (j in seq(1, SampleWidth )) {
i3 = c(i3, i2 + j )
i3 = c(i3, i2 - j )
}

I tried to tackle this with seq and the apply families but got nowhere

Thanks and Happy New Year

Paolo

	[[alternative HTML version deleted]]

______________________________________________
R-help at 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.

Charles C. Berry                            Dept of Family/Preventive Medicine
cberry at tajo.ucsd.edu			    UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901