On Dec 5, 2012, at 6:47 PM, Brian Feeny wrote:
I would like to take the values of observations and map them to a
new index. I am not sure how to accomplish this. The result would
look like so:
x[1,2,3,4,5,6,7,8,9,10]
becomes
y[2,4,6,8,10,12,14,16,18,20]
This suggests to me that you are having difficulty transfering your
Matlab knowldege to R.
The "newindex" would not necessarily be this sequence, but a
sequence I have stored in a vector, so it could be all kinds of
values. here is what happens:
x <- rnorm(10)
myindex <- seq(from = 1,to = 20, by = 2)
y <- numeric()
y[myindex] <- x
y
[1] -0.03745988 NA -0.09078822 NA
0.92484413 NA 0.32057426 NA
[9] 0.01536279 NA 0.02200198 NA
0.37535438 NA 1.46606535 NA
[17] 1.44855796 NA -0.05048738
So yes, it maps the values to my new indexes, but I have NA's. The
result I want would look like this instead:
The only structure in R that allows NULL values is a list. Matrices
need to have either value or NA.
[1] -0.03745988
[3] -0.09078822
[5] 0.92484413
[7] 0.32057426
[9] 0.01536279
[11] 0.02200198
[13] 0.37535438
[15] 1.46606535
[17] 1.44855796
[19] -0.05048738
and remove the NA's. I tried this with na.omit() on x, but it looks
like so:
x <- rnorm(10)
myindex <- seq(from = 1,to = 20, by = 2)
y <- numeric()
y[myindex] <- na.omit(x)
y
[1] 0.87399523 NA -0.39908184 NA
0.14583051 NA 0.01850755 NA
[9] -0.47413632 NA 0.88410517 NA
-1.64939190 NA 0.57650807 NA
[17] 0.44016971 NA -0.56313802
However it will not display the way you were inteniding:
> y <- list()
> y[seq(1,20, by=2)] <- 1:10
> y
[[1]]
[1] 1
[[2]]
NULL
[[3]]
[1] 2
[[4]]
NULL
[[5]]
[1] 3
snipped
--
David.
Brian
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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David Winsemius, MD
Alameda, CA, USA
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
