Re: [R] Subset a list

From: Chuck Cleland <ccleland_at_optonline.net>
Date: Tue 23 May 2006 - 08:41:51 EST

Doran, Harold wrote:
> I have a data frame of ~200 columns and ~20,000 rows where each column
> consists of binary responses (0,1) and a 9 for missing data. I am
> interested in finding the columns for which there are fewer than 100
> individuals with responses of 0.
>
> I can use an apply function to generate a table for each column, but I'm
> not certain whether I can subset a list based on some criterion as
> subset() is designed for vectors, matrices or dataframes.
>
> For example, I can use the following:
> tt <- apply(data, 2, table)
>
> Which returns an object of class list. Here is some sample output from
> tt
>
> $R0235940b
>
> 0 1 9
> 2004 1076 15361
>
> $R0000710a
>
> 0 9
> 2 18439
>
> $R0000710b
>
> 0 1 9
> 3333 3941 11167
>
> tt$R0000710a meets my criteria and I would want to be able to easily
> find this instead of rolling through the entire output. Is there a way
> to subset this list to identify the columns which meet the criteria I
> note above?

How about this?

newdf <- mydf[,colSums(mydf == 0) < 100]

> Thanks,
> Harold
>
>
>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
>

-- 
Chuck Cleland, Ph.D.
NDRI, Inc.
71 West 23rd Street, 8th floor
New York, NY 10010
tel: (212) 845-4495 (Tu, Th)
tel: (732) 512-0171 (M, W, F)
fax: (917) 438-0894

______________________________________________
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Received on Tue May 23 08:50:42 2006

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.1.8, at Tue 23 May 2006 - 10:10:18 EST.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help. Please read the posting guide before posting to the list.