On Jan 21, 2010, at 12:38 PM, b k wrote:

Hello,

I know there must be a simple soluton to this problem but it eludes me
currently.

My data is partitioned into two subsets, each subset has a common column
factor but with varying levels:

levels(fdf_ghc$AgeDemo)
[1] "26TO35" "36TO45" "46TO55" "56TO65" "66TO75" "76TO85"
levels(fdf_ghcnull$AgeDemo)
[1] "26TO35" "36TO45" "46TO55" "56TO65" "66TO75" "76TO85" "86TO100"
table(fdf_ghc$AgeDemo)
26TO35 36TO45 46TO55 56TO65 66TO75 76TO85
    6     14     21     31     19     14
table(fdf_ghcnull$AgeDemo)
26TO35  36TO45  46TO55  56TO65  66TO75  76TO85 86TO100
     5       5      10       7       8       4       1
I need to construct a common contingency table from the two lists, but rbind
recycles values due to the differing levels:

rbind(table(fdf_ghc$AgeDemo), table(fdf_ghcnull$AgeDemo))
    26TO35 36TO45 46TO55 56TO65 66TO75 76TO85 86TO100
[1,]      6     14     21     31     19     14       6
[2,]      5      5     10      7      8      4       1
Warning message:
In rbind(table(fdf_ghc$AgeDemo), table(fdf_ghcnull$AgeDemo)) :
number of columns of result is not a multiple of vector length (arg 1)

fdf_ghc<- data.frame(AgeDemo=factor( c("26TO35", "36TO45", "46TO55", "56TO65", "66TO75", "76TO85") )) fdf_ghcnull <- data.frame(AgeDemo= factor( c( "26TO35", "36TO45", "46TO55", "56TO65", "66TO75" ,"76TO85", "86TO100") ))

table( rbind(subset(fdf_ghcnull, select=AgeDemo), subset(fdf_ghc, select=AgeDemo)) )
# You need a strategy that prevents wiping out the factor level labels.
# in my test case:

 26TO35  36TO45  46TO55  56TO65  66TO75  76TO85 86TO100
      2       2       2       2       2       2       1

Whereas concatenation seemed to remove the factor labels although it keeps the counts:
> factor(c(fdf_ghcnull$AgeDemo, fdf_ghc$AgeDemo))
 [1] 1 2 3 4 5 6 7 1 2 3 4 5 6
Levels: 1 2 3 4 5 6 7


I need something I can pass to fisher.test() or chisq.test().

I'm not sure I see how those would accept a single factor or one row table for a test.

--

David Winsemius, MD
Heritage Laboratories
West Hartford, CT

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