[R] merge counts from table()

[David L Carlson]

If you know all of the categories in advance, you can convert x and y to
factors and then sum the tables:

> x<-1:4
> y<-2:5
> x <- factor(x , levels=1:5) # list all possible categories
> y <- factor(y , levels=1:5)
> table(x)
x
1 2 3 4 5 
1 1 1 1 0 
> table(y)
y
1 2 3 4 5 
0 1 1 1 1 
> table(c(x, y))

1 2 3 4 5 
1 2 2 2 1 
> table(x) + table(y)
x
1 2 3 4 5 
1 2 2 2 1

----------------------------------------------
David L Carlson
Associate Professor of Anthropology
Texas A&M University
College Station, TX 77843-4352


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Francois Pepin
> Sent: Monday, August 13, 2012 1:26 PM
> To: r-help at r-project.org
> Subject: [R] merge counts from table()
> 
> Hi everyone,
> 
> Is there an easy way to combine the counts from table()?
> 
> Let's say that I have:
> x<-1:4
> y<-2:5
> 
> I want to replicate:
> table(c(x,y))
> 
> using only table(x) and table(y) as input.
> 
> The reason is that it's cumbersome to carry all the values around when
> all I care about are the counts. The actual situation has about a
> billion counts over ~150 categories.
> 
> I know there's got to be a number of ways of doing things (plyr comes
> to mind), but I can't seem to find how to accomplish it.
> 
> Thanks,
> 
> François Pepin
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