On Fri, Mar 23, 2012 at 10:56:11AM +0100, Petr Savicky wrote:
> On Thu, Mar 22, 2012 at 11:42:53AM -0700, aly wrote:
[...]
> > I want to randomly select two rows but they have to be from different fam.
> > The fist part (random selection), I got it by doing:
> >
> > > ran <- sample(nrow (fish), si
On Thu, Mar 22, 2012 at 11:42:53AM -0700, aly wrote:
> Hi,
>
> I want to randomly pick 2 fish born the same day but I need those
> individuals to be from different families. My table includes 1787 fish
> distributed in 948 families. An example of a subset of fish born in one
> specific day would l
Here's another way:
With d1 as your data frame,
library(plyr)
d2 <- ddply(d1, .(fam), function(x) x[sample(nrow(x), 1), ])
d2[sample(nrow(d2), 2), ]
If you have to take account of the 'only one family' case, you
can wrap this in a function with an appropriate check:
fish <- function(d){
You could avoid the loop to run for ever by introducing a stop() check.
Here is an example using Dr. Savicky's code:
# function to sample B pairs of
# fishes from different families
# -- d has columns fam, born, spawn
foo <- function(d, B){
# internal function
foo <- function(d){
On Thu, Mar 22, 2012 at 11:42:53AM -0700, aly wrote:
> Hi,
>
> I want to randomly pick 2 fish born the same day but I need those
> individuals to be from different families. My table includes 1787 fish
> distributed in 948 families. An example of a subset of fish born in one
> specific day would l
Hi,
I want to randomly pick 2 fish born the same day but I need those
individuals to be from different families. My table includes 1787 fish
distributed in 948 families. An example of a subset of fish born in one
specific day would look like:
>fish
fam born spawn
25 46 43
25 46
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