[R] arrange data for simple regression analysis

[Tomás Revilla]

Hello, I want to arrange data from a table to perform a simple
regression. All the examples I saw deal with paired data, e.g. 'x' and
'y' have the same dimensions (e.g. 5 values for x and 5 for y).

But I have more than one 'y' for each 'x' value, e.g. the data file
has a x = 0, 30, 60, and 120 columns. And for each of them I have
several replicate responses (e.g. individuals), not allways the same
number. After I read the data with read.table(), ending with 4
columns, what is next? how can I regress this against c(0, 30, 60,
120)?

0       -->   n1 y values
30     -->  n2 y values
60     --> n3 y values
120  --> n4 y values

Thanks,

Tomas