[R] histogram frequency weighing
Sebastian P. Luque
spluque at gmail.com
Sun Sep 17 22:12:30 CEST 2006
Fellow R-helpers,
Suppose we create a histogram as follows (although it could be any vector
with zeroes in it):
R> lenh <- hist(iris$Sepal.Length, br=seq(4, 8, 0.05))
R> lenh$counts
[1] 0 0 0 0 0 1 0 3 0 1 0 4 0 2 0 5 0 6 0 10 0 9 0 4 0
[26] 1 0 6 0 7 0 6 0 8 0 7 0 3 0 6 0 6 0 4 0 9 0 7 0 5
[51] 0 2 0 8 0 3 0 4 0 1 0 1 0 3 0 1 0 1 0 0 0 1 0 4 0
[76] 0 0 1 0 0
and we wanted to apply a weighing scheme where frequencies immediately
following (and only those) empty class intervals (0) should be adjusted by
averaging them over the number of preceding empty intervals + 1. For
example, the first frequency that would need to be adjusted in 'lenh' is
element 6 (1), which has 5 preceding empty intervals, so its adjusted
count would be 1/6. Similarly, the second one would be element 8 (3),
which has 1 preceding empty interval, so its adjusted count would be 3/2.
Can somebody please provide a hint to implement such a weighing scheme?
I thought about some very contrived ways to accomplish this, involving
'which' and 'diff', but I sense a function might already be available to
do this efficiently. I couldn't find relevant info in the usual channels.
Thanks in advance for any pointers.
Cheers,
--
Seb
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