# [R] histogram frequency weighing

From: Sebastian P. Luque <spluque_at_gmail.com>
Date: Sun 17 Sep 2006 - 20:12:30 GMT

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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