[R] Extracting values from a list

[Paul Hiemstra]

chipmaney schreef:
> I have run a kruskal.test() using the by() function, which returns a list of
> results like the following (subset of results):
>
> Herb.df$ID: 4-2
>        Kruskal-Wallis chi-squared = 18.93, df = 7, p-value = 0.00841
> --------------------------------------------------------------------
> Herb.df$ID: 44-1
>         Kruskal-Wallis chi-squared = 4.43, df = 6, p-value = 0.6187
>
>
> So then, how do extract a vector of p-values (i.e., result$p.value) for
> every element in the list?
>
>
>
>   
If result$p.value normally returns the p value from a kruskal.test 
result you can probably do something like:

vector_pvalues = sapply(result_from_by_list, function(x) x$p.value)

cheers,
Paul