Hey,
I am hoping someone can help me with a sampling question.
I have a data frame of 8 variables (the first column is the subjects' id):
SubID CSE1 CSE2 CSE3 CSE4 WSE1 WSE2 WSE3 WSE4
1 6 5 6 2 6 2 2 4
2 6 4 7 2 6 6 2 3
3 5 5 5 5 5 5 4 5
4 5 4 3 4 4 4 5 2
5 5 6 7 5 6 4 4 1
6 5 4 3 6 4 3 7 3
7 3 6 6 3 6 5 2 1
8 3 6 6 3 6 5 4 7
the 6 variables are categorized into two groups with CSE1, CSE2, CSE3, and
CSE4 in one group and the rest in another group.
>sample(data[,2:4],2,replace=FALSE)
CSE1 CSE2
1 6 5
2 6 4
3 5 5
4 5 4
5 5 6
6 5 4
7 3 6
8 3 6
Now I want to sample 1 column from another group of variables (i.e., WSE1,
WSE2, WSE3, WSE4), but I want to restrict a vector I am going to sample from
to only those columns that are not correspond to GROUP 1 variables I have
sampled. That is, I want to sample a column from WSE3, WSE4 Columns
corresponding to CSE1 and CSE2 (i.e., WSE1, WSE2) need to be dropped.
How can I do this? what if I want to repeat this whole process (drawing 2
random columns from CSE1, CSE2, CSE3, and CSE4 first, AND then another
random column from WSE1, WSE2, WSE3, and WSE4) for 1000 times. any ideas?
Many thanks in advance!!
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