RE: [R] Keeping factors with zero occurrences in "table" output

From: Wiener, Matthew <matthew_wiener_at_merck.com>
Date: Thu 21 Apr 2005 - 02:15:34 EST


Ravi --

If you use table on a factor, you'll get 0's if appropriate:

> table(sample(1:5, 10, replace = TRUE)) #no 2's, by chance

1 3 4 5
3 1 2 4

> table(sample(1:5, 20, replace = TRUE)) # no 6's here, so 6 doesn't show
up

1 2 3 4 5
3 5 2 5 5

## now make it a factor, and you get 0 3's and 0 6's
> table(factor(sample(1:5, 20, replace = TRUE), levels = 1:6))

 1 2 3 4 5 6
 5 4 0 1 10 0

## just happened to get no 3's in previous sample; it doesn't happen every time:
> table(factor(sample(1:5, 20, replace = TRUE), levels = 1:6))

1 2 3 4 5 6
7 3 3 5 2 0

You can probably create the factor you want with "interaction" on participants and ranks.

Hope this helps,

Matt Wiener

-----Original Message-----
From: r-help-bounces@stat.math.ethz.ch
[mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Ravi Varadhan Sent: Wednesday, April 20, 2005 11:38 AM To: r-help@stat.math.ethz.ch
Subject: [R] Keeping factors with zero occurrences in "table" output

Dear R group,  

I have a data frame which contains data on preferences on 7 items (ranks 1 through 7) listed by each participant. I would like to tabulate this in a 7x7 table where the rows would be the items and the columns would be the number of times that item received a particular rank.  

I tried doing this by creating a matrix by "rbind"ing each vector obtained using "table" on each item. This, however, does not work because there are some items which didn't receive some of the ranks, so "table" does not list that item. Is there a way to force it to list the item and give a "0" to it? Or, is there a simpler way to solve this problem?  

Thanks for any help,

Ravi.  


Ravi Varadhan, Ph.D.

Assistant Professor, The Center on Aging and Health

Division of Geriatric Medicine and Gerontology

Johns Hopkins University

Ph: (410) 502-2619

Fax: (410) 614-9625

Email: <mailto:rvaradhan@jhmi.edu> rvaradhan@jhmi.edu


 

        [[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

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 Thu Apr 21 03:34:17 2005

This archive was generated by hypermail 2.1.8 : Fri 03 Mar 2006 - 03:31:18 EST