R help - Mar 2008 - 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

_________________________________________________________________
MSN ÖÐÎÄÍø£¬×îÐÂʱÉÐÉú»î×ÊѶ£¬°×Áì¾Û¼¯ÃÅ»§¡£

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On Mar 7, 2008, at 10:50 AM, zhihuali wrote:
>
> 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?
>
Does ?subset do what you want?
> Thank you very much!
>
>
> Zhihua Li
>
Haris Skiadas
Department of Mathematics and Computer Science
Hanover College

Un texte encapsul? et encod? dans un jeu de caract?res inconnu a ?t? nettoy?...
Nom : non disponible
Url :
https://stat.ethz.ch/pipermail/r-help/attachments/20080307/3424129d/attachment.pl

Try:

with(m, which((x >= 10 & y == "A")))

On 07/03/2008, zhihuali <lzhtom at hotmail.com>
wrote:
>
>  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
>
>
>  _________________________________________________________________
>  MSN ????????????????????
>
>         [[alternative HTML version deleted]]
>
>
> ______________________________________________
>  R-help at r-project.org mailing list
>  https://stat.ethz.ch/mailman/listinfo/r-help
>  PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
>  and provide commented, minimal, self-contained, reproducible code.
>
>

-- 
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O

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

_________________________________________________________________
MSN ????????????????????????????????????????

	[[alternative HTML version deleted]]