[R] contingency table on data frame

[John Kane]

It is not a good idea to use "sample' when building an
example like this!  Running the code does not give the
example dataframe.

This is crude but it will do what you want.

 x <- "  Z Y       X
   1 4     Yes
   2 1      No
   3 2 Perhaps
   4 3     Yes
   5 4      No
   6 5      No
   7 1     Yes
   8 4 Perhaps
   9 4     Yes
  10 2 Perhaps "
  
  xx <- read.table(textConnection(x), header=TRUE,
as.is=TRUE); xx
 
 df1 <- data.frame(xx[,3],xx[,2]) ; df1
 
 df2  <- unique(df1)
 table(df2[,1]) 

 


--- Karin Lagesen <karin.lagesen at medisin.uio.no>
wrote:

> 
> I am sorry if this is a faq or tutorial somewhere,
> but I am unable to
> solve this one.
> 
> What I am looking for is a count of how many
> different
> categories(numbers in this case) that appears for a
> given factor.
> 
> Example:
> 
> > l <- c("Yes", "No", "Perhaps")
> > x <- factor( sample(l, 10, replace=T), levels=l )
> > m <- c(1:5)
> > y <- factor( sample(m, 10, replace=T), levels=m )
> > z = c(1:10)
> > my_df = data.frame("Z" = z, "Y"= y, "X" = x)
> > my_df
>     Z Y       X
> 1   1 4     Yes
> 2   2 1      No
> 3   3 2 Perhaps
> 4   4 3     Yes
> 5   5 4      No
> 6   6 5      No
> 7   7 1     Yes
> 8   8 4 Perhaps
> 9   9 4     Yes
> 10 10 2 Perhaps
> > 
> 
> I am now looking for a table that will give me this:
> 
> Yes      3       # Yes has these ys: 4,3,1,4, two
> are the same, ergo 3
> No       3       # No has these ys: 1,4,5
> Perhaps  2       # Perhaps has these ys: 2,4,2
> 
> My dataframe has lots of other colums too, but I
> only want this
> information out.



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