# [R] Applying a function

Joanie Van De Walle joanie.van-de-walle.1 at ulaval.ca
Fri Dec 23 16:25:23 CET 2011

```   Hi,

I need help writing a function

I capture seal pups mutliple times during the lactation season in order to
monitor their growth rate. When I release them, the recovery (mother-pup)
time is not the same for all individuals. I want to know if individuals that
recover their mother the fastest are the ones with the highest growth rates.

So, I noted at every release if the pup reovered his mother before we leave
(yes or no). My dataframe looks like this

Capture nb individual individual capture motherrecovery growth rate
1          1          1                  n              0.5
2          1          2                  y              0.5
3          1          3                  y              0.5
4          1          4                  y              0.5
5          1          5                  n              0.5
6          2          1                  y              0.3
7          2          2                  y              0.3
8          3          1                  y              0.4
9          3          2                  n              0.4
10         3          3                  y              0.4
...

I want to calculate a rate of mother recovery by individual, i.e. nb of
recoveries (y)/nb of captures. So for indivial 1 it would be 3/5 = 0.6. I
want  to write a function that does this for all the individuals in my
dataframe,  i.e. around 400 individuals (this is why I want to write a
function, it would be too long by hand)

Thank you,

Joanie Van de Walle

Ã‰tudiante Ã  la MaÃ®trise en Biologie