[R] dataframe indexing by number of cases per group
Hello, assume we have following dataframe: group -c(rep(A,5),rep(B,6),rep(C,4)) x - c(runif(5,1,5),runif(6,1,10),runif(4,2,15)) df - data.frame(group,x) Now I want to select all cases (rows) for those groups which have more or equal 5 cases (so I want to select all cases of group A and B). How can I use the indexing for such questions? df[??]... I think it is probably quite easy but I really don't know how to do that at the moment. maybe someone can help me... /johannes -- __ R-help@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.
Re: [R] dataframe indexing by number of cases per group
A very similar question was asked a couple of days ago - see the thread titled Removing rows in dataframe w'o duplicated values - in particular, the responses by Dimitris Rizopoulos and David Winsemius. The adaptation to this problem is df[ave(as.numeric(df$group), as.numeric(df$group), FUN = length) 4, ] groupx 1 A 3.903747 2 A 3.599547 3 A 2.449991 4 A 2.740639 5 A 4.268988 6 B 8.649600 7 B 5.493841 8 B 1.892154 9 B 6.781754 10 B 1.459250 11 B 6.749522 HTH, Dennis On Thu, Nov 24, 2011 at 4:02 AM, Johannes Radinger jradin...@gmx.at wrote: Hello, assume we have following dataframe: group -c(rep(A,5),rep(B,6),rep(C,4)) x - c(runif(5,1,5),runif(6,1,10),runif(4,2,15)) df - data.frame(group,x) Now I want to select all cases (rows) for those groups which have more or equal 5 cases (so I want to select all cases of group A and B). How can I use the indexing for such questions? df[??]... I think it is probably quite easy but I really don't know how to do that at the moment. maybe someone can help me... /johannes -- __ R-help@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. __ R-help@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.
Re: [R] dataframe indexing by number of cases per group
On Thu, Nov 24, 2011 at 7:02 AM, Johannes Radinger jradin...@gmx.at wrote:
Hello,
assume we have following dataframe:
group -c(rep(A,5),rep(B,6),rep(C,4))
x - c(runif(5,1,5),runif(6,1,10),runif(4,2,15))
df - data.frame(group,x)
Now I want to select all cases (rows) for those groups
which have more or equal 5 cases (so I want to select
all cases of group A and B).
How can I use the indexing for such questions?
df[??]... I think it is probably quite easy but I really
don't know how to do that at the moment.
maybe someone can help me...
Here are three approaches:
subset(merge(df, xtabs(~ group, df)), Freq = 5)
:
subset(transform(df, len = ave(x, group, FUN = length)), len = 5)
library(sqldf)
sqldf('select a.*
from df a join (select group, count(*) count from df group by group)
using (group)
where count = 5')
--
Statistics Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com
__
R-help@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.
Re: [R] dataframe indexing by number of cases per group
Hi,
thank you for your suggestions.
I think I'll stay with Dennis' approach
as this is a real indexing approach:
df[ave(as.numeric(df$group), as.numeric(df$group), FUN = length) 4, ]
I'll try that out now
best regards
/Johannes
Original-Nachricht
Datum: Thu, 24 Nov 2011 09:12:57 -0500
Von: Gabor Grothendieck ggrothendi...@gmail.com
An: Johannes Radinger jradin...@gmx.at
CC: r-help@r-project.org
Betreff: Re: [R] dataframe indexing by number of cases per group
On Thu, Nov 24, 2011 at 7:02 AM, Johannes Radinger jradin...@gmx.at
wrote:
Hello,
assume we have following dataframe:
group -c(rep(A,5),rep(B,6),rep(C,4))
x - c(runif(5,1,5),runif(6,1,10),runif(4,2,15))
df - data.frame(group,x)
Now I want to select all cases (rows) for those groups
which have more or equal 5 cases (so I want to select
all cases of group A and B).
How can I use the indexing for such questions?
df[??]... I think it is probably quite easy but I really
don't know how to do that at the moment.
maybe someone can help me...
Here are three approaches:
subset(merge(df, xtabs(~ group, df)), Freq = 5)
:
subset(transform(df, len = ave(x, group, FUN = length)), len = 5)
library(sqldf)
sqldf('select a.*
from df a join (select group, count(*) count from df group by
group)
using (group)
where count = 5')
--
Statistics Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com
--
__
R-help@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.
