Re: [R] How to compute within-group mean and sd?

2012-03-25 Thread reeyarn 
Thanks Rui, Greg, and Michael.
Your answers helped a lot!

Best,
Reeyarn

On Sun, Mar 25, 2012 at 1:02 AM, Rui Barradas rui1...@sapo.pt wrote:

 Hello,


 You can use sql with package 'sqldf'.
  library(sqldf) # It needs package 'tcltk'
 ?sqldf
  tbl - data.frame(firm_id=rep(c(1,2), 10), value=rnorm(20))
  sqldf(SELECT firm_id, count(*), avg(value), stdev(value)
  FROM tbl
  GROUP BY firm_id;)

 I've changed the name of your data.frame because 'table' is an R function.
  Hope this helps,

 Rui Barradas



[[alternative HTML version deleted]]

__
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] How to compute within-group mean and sd?

2012-03-24 Thread reeyarn 
Hi, I want to run something like
  SELECT firm_id, count(*), mean(value), sd(value)
  FROM table
  GROUP BY firm_id;

But I have to write a for loop like
  for ( id in unique(table$firm_id ) {
print(paste(  id, mean(table[firm_id == id, value])  ))
  }

Is there any way to do it easier? Thanks :)


Best,
Reeyarn Lee

[[alternative HTML version deleted]]

__
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] How to compute within-group mean and sd?

2012-03-24 Thread R. Michael Weylandt 
This is a very commonly used paradigm in R and there are many
different answers, one would be tapply(). You could also look at the
plyr package.

Michael

On Sat, Mar 24, 2012 at 11:32 AM, reeyarn reey...@gmail.com wrote:
 Hi, I want to run something like
  SELECT firm_id, count(*), mean(value), sd(value)
  FROM table
  GROUP BY firm_id;

 But I have to write a for loop like
  for ( id in unique(table$firm_id ) {
    print(paste(  id, mean(table[firm_id == id, value])  ))
  }

 Is there any way to do it easier? Thanks :)


 Best,
 Reeyarn Lee

        [[alternative HTML version deleted]]

 __
 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] How to compute within-group mean and sd?

2012-03-24 Thread Greg Snow 
In addition to Michael's answers, there are packages that allow you to
use SQL syntax on R data objects, so you could probably just use what
you are familiar with.

On Sat, Mar 24, 2012 at 9:32 AM, reeyarn reey...@gmail.com wrote:
 Hi, I want to run something like
  SELECT firm_id, count(*), mean(value), sd(value)
  FROM table
  GROUP BY firm_id;

 But I have to write a for loop like
  for ( id in unique(table$firm_id ) {
    print(paste(  id, mean(table[firm_id == id, value])  ))
  }

 Is there any way to do it easier? Thanks :)


 Best,
 Reeyarn Lee

        [[alternative HTML version deleted]]

 __
 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.



-- 
Gregory (Greg) L. Snow Ph.D.
538...@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] How to compute within-group mean and sd?

2012-03-24 Thread Rui Barradas 
Hello,


Reeyarn_李智洋_10928113 wrote
 
 Hi, I want to run something like
   SELECT firm_id, count(*), mean(value), sd(value)
   FROM table
   GROUP BY firm_id;
 
 But I have to write a for loop like
   for ( id in unique(table$firm_id ) {
 print(paste(  id, mean(table[firm_id == id, value])  ))
   }
 
 Is there any way to do it easier? Thanks :)
 
 
 Best,
 Reeyarn Lee
 
   [[alternative HTML version deleted]]
 
 __
 R-help@ 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.
 

You can use sql with package 'sqldf'.

library(sqldf) # It needs package 'tcltk'
?sqldf

tbl - data.frame(firm_id=rep(c(1,2), 10), value=rnorm(20))

sqldf(SELECT firm_id, count(*), avg(value), stdev(value)
  FROM tbl
  GROUP BY firm_id;)

I've changed the name of your data.frame because 'table' is an R function.

Hope this helps,

Rui Barradas


--
View this message in context: 
http://r.789695.n4.nabble.com/How-to-compute-within-group-mean-and-sd-tp4501504p4501709.html
Sent from the R help mailing list archive at Nabble.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.