extracting a subTable
Hello, Something you can do is first, find the indexes to extract as follows: indexes.to.extract <- tapply(table.1$Seq, tablle.1$ID, max) Then, table.2 is just table.2 <- table.1[ indexes.to.extract, ] You could do it in just one line. I think this is as efficient as it can get. Best regards, Carlos J. Gil Bellosta http://www.datanalytics.com
On Wed, 2009-01-14 at 16:30 -0500, Jorge Nieves wrote:
Hi, I have a BIG table with data organized by ID, see example on Table#1 bellow. I would like to extract a smaller table with the same number of columns. The rows should include only the last ROW of each ID. Table# 2 is an example extracted form table #1. I tried using the SUBSET function and plan to loop, but I was wondering if someone out there has a more efficient way to accomplish this. You recommendations are highly appreciated. Jorge Table # 1 Table # 2 Seq ID X1 X2 Seq ID X1 X2 1 15 -616 796 12 15 -148 878 2 15 -661 -455 20 20 -515 1,802 3 15 -355 -1,639 27 45 -138 179 4 15 -1,226 -97 34 70 1,348 840 5 15 506 985 6 15 -612 76 7 15 947 122 8 15 -45 1,980 9 15 295 -1,827 10 15 1,490 -743 11 15 115 1,283 12 15 -148 878 13 20 359 1,297 14 20 -185 -430 15 20 481 800 16 20 1,567 874 17 20 2,365 -167 18 20 1,636 1,649 19 20 -2,741 337 20 20 -515 1,802 21 45 90 624 22 45 -221 345 23 45 -2,168 -1,734 24 45 1,056 -1,070 25 45 678 -80 26 45 1,747 -74 27 45 -138 179 28 70 1,152 -3,167 29 70 -802 -337 30 70 -388 263 31 70 812 342 32 70 -576 972 33 70 653 -737 34 70 1,348 840 Jorge Nieves Phone 212.782.7083 Fax 212.642.7644 [[alternative HTML version deleted]]
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