[R] Randomly splitting a data frame in half

[Christopher David Desjardins]

Thanks that makes perfect sense!
Chris

On 3/19/09 1:17 PM, Dimitris Rizopoulos wrote:
> well, you need to keep track of the rows you sampled, e.g.,
>
> dat <- data.frame(x = rnorm(20), y = rnorm(20), w = rnorm(20))
>
> ii <- seq_len(nrow(dat))
> ind1 <- sample(ii, 10)
> ind2 <- ii[!ii %in% ind1]
> dat[ind1, ]
> dat[ind2, ]
>
>
> I hope it helps.
>
> Best,
> Dimitris
>
>
> Christopher David Desjardins wrote:
>> I have a data frame in long format and I would like to randomly 
>> divide this data frame in half. The data frame consists of 39622 rows 
>> and I initially tried ...
>>
>> randomsample1 <- data[sample(nrow(data),19811), ]
>>
>> Where allows me to randomly select half of the rows and assign them 
>> to randomsample1 but then I couldn't figure out how to select those 
>> rows that were not selected and assign them to randomsample2.
>>
>> Please cc me if you reply as I'm a digest subscriber.
>> Thanks,
>> Chris
>>
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>