[R] simple loop questions

From: <xueke_at_pdx.edu>
Date: Sat, 23 Apr 2011 03:31:48 -0700


Hi all,

I am trying to write a loop to return the matched index for a column of values. Here is an simple example of this,

A B
0 5
1 2
2 2
3 4
4 1
5 4
6 2

In this case, A is an index column for B. Now I have this new column C with just two values of 2 and 4. I want to match column C with column B, and return the matched indexes. So what I desire is to return:

[1] 1 2 6
[2] 3 5

Since value 2 corresponds to indexes 1,2,6, and 4 corresponds to indexes 3,5.

Is there any way to write a loop to have this done? Thank you for the help.

Xueke



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