[R] extracting max row from data matrix

Shubha Vishwanath Karanth shubhak at ambaresearch.com
Mon Sep 8 09:46:45 CEST 2008

> aggregate(x$weight,list(x$fruit),max)

  Group.1   x
1   apple 1.6
2  orange 1.6

Shubha Karanth | Amba Research
Ph +91 80 3980 8031 | Mob +91 94 4886 4510 
Bangalore * Colombo * London * New York * San José * Singapore * www.ambaresearch.com
-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Srinivas Iyyer
Sent: Monday, September 08, 2008 7:55 AM
To: r-help at stat.math.ethz.ch
Subject: [R] extracting max row from data matrix

dear group, 
i have a data matrix with some replicate items with different values. I want to extract the row with max value. 

for example:
> x
   fruit weight
1  apple    1.3
2  apple    1.5
3  apple    1.6
4 orange    1.4
5 orange    1.6

x is a data frame. 
I want to extract unique items from fruits that has max weight. 

that is:

3  apple    1.6
5 orange    1.6

I want to be able to use apply functions. Could some one lend some help please. 


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