[R] Sample without replacement
Hello, I have a simple problem (checked the archives and the appropriate
help pages, to no avail). I want to creat a vector that is length(2000).
The vector is to consist of two strings( std and dev) with 1760 stds
and 240 devs. Furthermore, for each element of the vector, i want the
selection of one of the strings to be approx. random. The end result will
be a vector with the following proportions: .12 dev and .88 std.
My solution, below, almost works, but i don't get the exact desired
proportions:
sample.from.vector - c(rep(std,1760),rep(dev,240))
make.vector - rep(99,2000)
for (i in 1:2000){
make.vector[i] - sample(sample.from.vector,1,replace=F)
}
As I understand the above code (which is not very well, obviously), each
iteration assigns one element from the sample.from.vector to the current
make.vector element; the element choosen from sample.from.vector is
tagged so that i is not selected again. However, after the loop,
make.vector contains, for example, 1758 stds and 242 devs. Each
iteration results in a different proportion of stds and devs (although
close to the desired, not right on).
Any help would be greatly apprecitated.
-Mark Orr
Mark G. Orr
Postdoctoral Research Fellow
Dept. of Neuroscience
RM 825 Kennedy Center
Albert Einstein College of Medicine
Bronx, NY 10461
718-430-2610
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PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] THanks, random/repl. prob. SOLVED.
Thanks for the help, it worked. Mark G. Orr Postdoctoral Research Fellow Dept. of Neuroscience RM 825 Kennedy Center Albert Einstein College of Medicine Bronx, NY 10461 718-430-2610 __ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] SORTING Arrays by index value
Hello, I'm somewhat new to R. I've searched the archive for the last year and tried to consult the manual pages for the following problem, but did not find an answer. I want to sort an array by the index values. Here is the array acc.gp.bl.wtmn Gp17 Gp4 1 0.5703125 0.6406250 10 0.7812500 0.7109375 11 0.8046875 0.7343750 12 0.8359375 0.7890625 13 0.8515625 0.7109375 14 0.8281250 0.7343750 15 0.8671875 0.7812500 16 0.8125000 0.7578125 17 0.7734375 0.750 18 0.800 0.780 19 0.870 0.730 2 0.8046875 0.7265625 20 0.830 0.740 21 0.750 0.800 22 0.770 0.760 23 0.820 0.780 24 0.760 0.740 25 0.810 0.800 3 0.7578125 0.7812500 4 0.8203125 0.7890625 5 0.7890625 0.7421875 6 0.7265625 0.7812500 7 0.8125000 0.7421875 8 0.8515625 0.7265625 9 0.8203125 0.6953125 My question is: How do I sort by the first index (the values are 1:25) without losing the associated values per index value for the two columns(Gp17 and Gp4). I want ascending order (1:25) of the index values. Thank you in advance. -Mark Orr Postdoctoral Fellow Psychology Dept. Carnegie Mellon Univ. Pittsburgh, PA 15213 __ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help
