我有一个data.frame像这样：
df <- structure(list(X1 = c("PF00041", "PF00041", "PF00041", "PF00041",
"PF00041", "PF00041", "PF00041", "PF00041", "PF00041", "PF00047",
"PF00041", "PF00041", "PF00041", "PF00054", "PF00054", "PF02210",
"PF07679", "PF07714", "PF07714", "PF07714", "PF07714", "PF07714",
"PF07714", "PF00041", "PF00041", "PF00041"), X2 = c("PF00041",
"PF00041", "PF00041", "PF00041", "PF00041", "PF00041", "PF07679",
"PF07679", "PF07679", "PF13895", "PF00047", "PF00047", "PF00047",
"PF02210", "PF13895", "PF07645", "PF13895", "PF07714", "PF07714",
"PF07714", "PF07714", "PF07714", "PF07714", "PF13895", "PF13895",
"PF13895"), pfam_name.x = c("fn3", "fn3", "fn3", "fn3", "fn3",
"fn3", "fn3", "fn3", "fn3", "ig", "fn3", "fn3", "fn3", "Laminin_G_1",
"Laminin_G_1", "Laminin_G_2", "I-set", "Pkinase_Tyr", "Pkinase_Tyr",
"Pkinase_Tyr", "Pkinase_Tyr", "Pkinase_Tyr", "Pkinase_Tyr", "fn3",
"fn3", "fn3"), pfam_name.y = c("fn3", "fn3", "fn3", "fn3", "fn3",
"fn3", "I-set", "I-set", "I-set", "Ig_2", "ig", "ig", "ig", "Laminin_G_2",
"Ig_2", "EGF_CA", "Ig_2", "Pkinase_Tyr", "Pkinase_Tyr", "Pkinase_Tyr",
"Pkinase_Tyr", "Pkinase_Tyr", "Pkinase_Tyr", "Ig_2", "Ig_2",
"Ig_2"), value.x = c("5", "5", "13", "13", "17", "17", "5", "13",
"17", "18", "5", "13", "17", "11", "11", "12", "14", "6", "6",
"15", "15", "20", "20", "5", "13", "17"), value.y = c("13", "17",
"5", "17", "5", "13", "14", "14", "14", "19", "18", "18", "18",
"12", "19", "8", "19", "15", "20", "6", "20", "6", "15", "19",
"19", "19")), row.names = c(2L, 3L, 4L, 6L, 7L, 8L, 10L, 11L,
12L, 13L, 15L, 16L, 17L, 19L, 20L, 25L, 27L, 29L, 30L, 31L, 33L,
34L, 35L, 38L, 39L, 40L), class = "data.frame")
我希望能够基于列value.x和value.y过滤此data.frame，但我不想保留被切换的行。例如，第1行的值分别为5和13，第3行的值分别为13和5，我想摆脱第3行。
我一开始尝试排序，但是因为我还有其他列，所以排序将所有列混合在一起。例如：
data.frame(unique(t(apply(df, 1, sort))), stringsAsFactors = F)
在此表中，我可以看到Pkinase_Tyr现在位于X1列中。