R 如何在所有对中执行一次发生的函数

我在这里问了一个很难回答的问题。我发现了一个好主意，我想试试

这是我的想法和数据（与那个问题的数据相同）

棘手的是，它应该在引用和另一个引用之间发生一次，例如，它应该只计算一次引用和另一个引用之间的距离

Afghanestankabolindia and Afghanestan

而不是

Afghanestan and Afghanestankabolindia 

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意味着引用总是最长的字符串

不确定您期望的输出格式是什么，但我认为这符合您的要求：

ref = as.character(df$label)
all_combs = as.data.frame(t(combn(ref[order(nchar(ref),decreasing = T)],2)))
all_combs$val = mapply(adist,all_combs$V1,all_combs$V2)

首先，我们创建所有组合（对

ref

向量进行排序，使第一个元素始终是较长的元素（即引用）。然后我们使用mapply计算所有组合的

adist

输出：

                      V1                  V2 val
1  Afghanestankabolindia  USAargentinabrazil  15
2  Afghanestankabolindia   indiaAfghanestan   15
3  Afghanestankabolindia    Afghanestankabol   5
4  Afghanestankabolindia        Holandnorway  17
5  Afghanestankabolindia       USAargentina   17
6  Afghanestankabolindia        Afghanestan   10
7  Afghanestankabolindia         holandindia  13
8  Afghanestankabolindia              holand  16
9  Afghanestankabolindia                 USA  21
10    USAargentinabrazil   indiaAfghanestan   16
11    USAargentinabrazil    Afghanestankabol  13
12    USAargentinabrazil        Holandnorway  14
13    USAargentinabrazil       USAargentina    7
14    USAargentinabrazil        Afghanestan   15
15    USAargentinabrazil         holandindia  13
16    USAargentinabrazil              holand  16
17    USAargentinabrazil                 USA  16
18     indiaAfghanestan     Afghanestankabol  10
19     indiaAfghanestan         Holandnorway  14
...               .....                .....  ..

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希望这有帮助！

非常感谢，我喜欢并接受了您的回答

ref = as.character(df$label)
all_combs = as.data.frame(t(combn(ref[order(nchar(ref),decreasing = T)],2)))
all_combs$val = mapply(adist,all_combs$V1,all_combs$V2)

                      V1                  V2 val
1  Afghanestankabolindia  USAargentinabrazil  15
2  Afghanestankabolindia   indiaAfghanestan   15
3  Afghanestankabolindia    Afghanestankabol   5
4  Afghanestankabolindia        Holandnorway  17
5  Afghanestankabolindia       USAargentina   17
6  Afghanestankabolindia        Afghanestan   10
7  Afghanestankabolindia         holandindia  13
8  Afghanestankabolindia              holand  16
9  Afghanestankabolindia                 USA  21
10    USAargentinabrazil   indiaAfghanestan   16
11    USAargentinabrazil    Afghanestankabol  13
12    USAargentinabrazil        Holandnorway  14
13    USAargentinabrazil       USAargentina    7
14    USAargentinabrazil        Afghanestan   15
15    USAargentinabrazil         holandindia  13
16    USAargentinabrazil              holand  16
17    USAargentinabrazil                 USA  16
18     indiaAfghanestan     Afghanestankabol  10
19     indiaAfghanestan         Holandnorway  14
...               .....                .....  ..