[R] Random sample from a data frame where ID column values don't match the values in an ID column in a second data frame

[David Winsemius]

On Mar 29, 2012, at 2:37 PM, inkhorn wrote:

> Hello,
>
> Let's say I've drawn a random sample () from a large data frame
> (main.df), and I want to create a second random sample (sample2.df)  
> where
> the values in its ID column *are not* in the equivalent ID column in  
> the
> first sample (sample1.df).  How would I go about doing this?
>
> In other words:
>
> The values in sample2.df$ID *are not found* in sample1.df$ID,  and  
> both
> samples are drawn from main.df.
>

?"%in%"

sample2.df <- main.df[ ! main.df[, "ID"] %in% sample1.df[, "ID"] , ]


> Thanks in advance,
> Matt Dubins
>
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David Winsemius, MD
West Hartford, CT