按两列分组并在R中合并级别 [英] Group by two columns and union of levels in R

问题描述

我被困在一个看似微不足道的问题上，但现在无法解决。我什至不知道如何正确地制定它，如果您有任何建议，欢迎您。
我有一个data.frame我想根据两列进行分组/索引。问题是，我要分组的行在那些列中没有共享相同的值。而是，某些行在一个列中具有相同的值，然后其中一些行在第二列中具有与其他行相同的值（我也希望将其包含在分组中）。这是一个最小的示例，我希望这可以使它更清晰一些：

I am stuck on a problem that seem trivial but I am unable to figure it out right now. I don't even know how to formulate it properly, if you have any suggestions, you are welcome. I have a data.frame which I want to group/index depending on two columns. The thing is, the rows I want to group do not share the same values in those columns. Rather, some rows have the same value in one column, and then some of those rows have a common value with different rows in the second column (which I also want to include in the grouping). Here is a minimal example, I hope this makes it a bit clearer:

id V1 V2 group_id
1   a  c        1
2   a  d        1
3   b  d        1
4   w  y        2
5   w  z        2
6   x  z        2

行1和行2共同具有列V1的值 a 。但是我不仅要对它们进行分组，还要对第3行进行分组，该行通过列V2的值 d 被连接。现在，我只能分别对行1,2和2,3进行分组。

Rows 1 and 2 have the value a of column V1 in common. But I not only want to group them, but also row 3, which is "connected" via the value d of column V2. Right now, I am only able to group rows 1,2 and 2,3 separately.

第二组也是如此，这里我想对值进行分组在V1中为 w 或在V2中为 z 。 x 和 y 无关。

The same is true for the 2nd group, here I want to group values with either w in V1 or z in V2. x and y are irrelevant.

任何帮助都是

推荐答案

以下是使用集群的方法 igraph 包中的函数：

Here's how you could do that with the cluster function from the igraph package:

library(igraph)
relations <- data.frame(from=df$V1,to=df$V2)
g <- graph_from_data_frame(relations)
group_id <- data.frame(V=names(clusters(g)$membership),
                       cluster=clusters(g)$membership,stringsAsFactors=FALSE)
left_join(df,group_id,by=c("V1"="V"))

  id V1 V2 group_id cluster
1  1  a  c        1       1
2  2  a  d        1       1
3  3  b  d        1       1
4  4  w  y        2       2
5  5  w  z        2       2
6  6  x  z        2       2

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