On Jul 15, 2015, at 12:12 PM, Robin Gropp wrote:
> Hi.
>
> I have a big data set which could be represented something like this:
>
> *plot fate*
> 1 S
> 2 M
> 3 S
> 3 S
> 3 M
> 4 S
> 4 S
> 5 S
> 5 M
> 5 S
> 5 S
> 6 M
> 7 M
>
> where plot is a location, and fate is either "survivorship" or
"mortality"
> ( a plant lives or dies.) Thus in plot 5 there are 4 plants. 3 of them
> survive, 1 dies.
> I want to figure out a way to make R calculate the fraction of individuals
> that survive in each plot for all of these. It is proving very challenging.
>
> Example: Plot 5 would return a survivorship value of 3/4 or 75%/
> Plot 3 would return a survivorship value of 2/3 or 66%
Divide the survivors by the number at risk.
tdat <- with( dat, table(plot, fate) ) # a matrix-like object
tdat[,'S']/rowSums(tdat)
1 2 3 4 5 6
1.0000000 0.0000000 0.6666667 1.0000000 0.7500000 0.0000000
7
0.0000000
>
> Any help would be much appreciated.
> Thank you
>
> [[alternative HTML version deleted]]
>
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David Winsemius
Alameda, CA, USA