Hi,
I am still new to R and have, in spite of searching all over, found no
"understandable" documentation for how to join two (or more) frequency
tables.
Why would I want to do that and what do I mean by "joining" ? Let me try
to explain:
I have a diagnosis form that allows registration of up to three diagnosis
codes on animals with birth defects, like this:
father.id diagnosis diagnosis2 diagnosis3
a 100 200 300
b 200 100 340
....
and so on.
As you can see the same diagnosis can show up in either field (1, 2 or 3).
I am interested in how many times each diagnosis shows up for offspring
from the same father (looking at inheritance)
The best I have come up with so far is
table(father.id, diagnosis)
table(father.id, diagnosis2)
table(father.id, diagnosis3)
which gives me the frequency counts for each combination of father.id and
diagnosis code
and then I manually join these tables together by cutting and pasting (in
Excel!!). Oh the horror!
The resulting table looks like this though and gives me what I want:
father.id 100 200 300 340
a 1 1 1 0
b 1 1 0 1
.....
This is incredibly cumbersome and therefore I want to find a way of doing
this completely in R script so that I have the code ready when I need it
again.
So far I have tried with several varieties of merge() and xtabs() but have
given up. I can not afford to spend more time on this and as a last resort
I'm hoping anyone here could pass me a tip.
I use R for modelling but I am so far finding it hard to wrap my head
around it when it comes to the pre-analysis data manipulation like this as
I am not proficient enough (i.e. do not quite understand) in the language
and data structure intricacies.
Regards,
Jan
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