问题
I have a data frame with 1000 observations on 20 variables.
I want to select only the rows that have a unique combination across columns, regardless of their order.
That is, if a combination is ABA and another is BAA, I want the code only to return one of these combinations.
To identify unique combinations I run a simple unique command across multiple variables.
How would you write such a code?
回答1:
We can sort the data by row using apply with MARGIN=1, then use duplicated to return the logical index, negate it and get the unique rows in the data.
dat[!duplicated(t(apply(dat, 1, sort))),]
来源：https://stackoverflow.com/questions/35592803/in-r-find-observations-with-unique-combinations-across-columns-regardless-thei