当行相等时从数据帧创建邻接矩阵

Question

我有一个类似于

的数据框

mydf <- data.frame(Country=c('USA','Brazil','China','Italy','Ghana','Brazil','USA','China','USA'),
                               Pattern=c('XXZ','XXX','XYX','XXZ','XXX','XXX','XYZ','XXX','XYZ'),
                               Value=c(1,2,5,4,1,2,3,1,6))

如果 Pattern 的行相等，我需要一个无向邻接矩阵，这会增加值。

例如，

    From     To   Pattern  Value
    Brazil  Brazil  XXX    4
    Brazil  China   XXX    3
    Brazil  Ghana   XXX    3

Answer 1

听起来你想要这个：

library(tidyverse)

mydf %>%
  split(.$Pattern) %>%
  map_dfr(~ .x %>%
       mutate(n = row_number()) %>%
       cross_join(., .) %>%
       filter(n.x != n.y, Country.x <= Country.y) %>%
       reframe(Value = `Value.x` + Value.y, .by = c(Country.x, Country.y)) %>%
       rename(From = Country.x, To = Country.y) %>%
       distinct(), .id = 'Pattern')

输出：

  Pattern   From     To Value
1     XXX Brazil  Ghana     3
2     XXX Brazil Brazil     4
3     XXX Brazil  China     3
4     XXX  China  Ghana     2
5     XXZ  Italy    USA     5
6     XYZ    USA    USA     9