How can I perform matrix operations on certain rows?

I have data stored in a large matrix (8 columns of hundreds of thousands of rows), for example:

Year D Val

1980 1 345

1980 2 320

1980 3 364

1981 1 400

1981 2 387

1981 3 209

1982 1 195

1982 2 358

1982 3 322

How can I plot/ save/ perform operations on the rows for certain years?

Many thanks.

Answer 1

[zepp]

What do you mean by 'certain'? Is there any condition that determines the selection of years. Then, you could use a logical array of length (nrows) and then select the years based on this logical array.

[Ryan Hickson]

No worries, I found what I was looking for. :)