📅  最后修改于: 2022-03-11 14:51:58.238000             🧑  作者: Mango
# example
df = expand.grid(A = c('a', 'b', 'c', 'd'),
B = c('a', 'b', 'c', 'd'))
# remove redundant combinations
df[!duplicated(data.frame(t(apply(df,1,sort)))),]