[R] create variables with indexes

[Jeff Newmiller]

In virtually every case where people think they need gobs of similarly-named variables, what they really need are vectors or data frames. I strongly recommend reading the Introduction to R document again to learn how to create them and access individual elements and subsets of elements.Data frames can be used to contain multiple "indexes" as you describe, and subset, logical vectors, and apply and the plyr library can be used to select and analyze parts of the data frame in a systematic manner.

"He, Yulei" <he at hcp.med.harvard.edu> wrote:

>Hi, there:
>
>Suppose I want create variables with indexes in their names, e.g., X_1_1, X_1_2, X_1_3, ..., X_1_10,  X_2_1, X_2_2, X_2_3, .. X_2_10,..., X_10_1, X_10_2, ... X_10_10. It looks like I need to use 2 indexes I and J so I is looped from 1 to 10, and J is looped from 1 to 10. But I don't know how to automatically produce X with these combination of indexes. Should I use paste function? Can someone help?
>
>Thanks.
>
>Yulei
>
>
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