locate the rows in a dataframe with some criteria

i <- with(M, which(x >= 10 & y == "A")) ## will get you the row indices.
 
m <- subset(M, x >= 10 & y == "A")  ## will get you the rows themselves

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of zhihuali
Sent: Saturday, 8 March 2008 1:51 AM
To: r-help at stat.math.ethz.ch
Subject: [R] locate the rows in a dataframe with some criteria


Hi, netters,

This is probably a rookie question but I couldn't find the answer after hours of searching and trying.

Suppose there'a a dataframe M:

x     y
10   A
13   B
8     A
 11   A

I want to locate the rows where x >=10 and y="A". I know how to do it to vectors by using 
which, but how to do it with the dataframe?

Thank you very much!


Zhihua Li

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