从R中的长表创建对称矩阵

debugcn 发表于 Dev

MENGYING NI

这是我的资料

df <- data.frame (Var1  <- c("a", "b", "c","d","e","b","c","d","e","c","d","e","d","e","e"),
                  Var2 <- c("a","a","a","a","a","b","b","b","b","c","c","c","d","d","e")
                  pre <- c(1,2,3,4,5,1,6,7,8,1,9,10,1,11,1) )

我想使用Var1和Var2函数作为行名和列名来构建对称矩阵，并且矩阵值是r中“ pre”中的对应数字，如下所示：

  a b c d e 
a 1 2 3 4 5
b 2 1 6 7 8 
c 3 6 1 9 10
d 4 7 9 1 11
e 5 8 10 11 1

这似乎是一个简单的问题，但是我在Google上搜索了很多帖子，但尚未解决，所以我来这里问，谢谢！

Mengying

罗纳克·沙

您可以先获取宽格式的数据。

library(dplyr)
library(tidyr)

mat <- df %>%
  pivot_wider(names_from = Var2, values_from = pre, values_fill = 0) %>%
  column_to_rownames('Var1') %>%
  as.matrix()

mat
#  a b  c  d e
#a 1 0  0  0 0
#b 2 1  0  0 0
#c 3 6  1  0 0
#d 4 7  9  1 0
#e 5 8 10 11 1

由于具有对称矩阵，因此可以将下三角矩阵复制到上三角。

mat[upper.tri(mat)] <- t(mat)[upper.tri(mat)]
mat

#  a b  c  d  e
#a 1 2  3  4  5
#b 2 1  6  7  8
#c 3 6  1  9 10
#d 4 7  9  1 11
#e 5 8 10 11  1

数据

df <- data.frame (Var1  = c("a", "b", "c","d","e","b","c","d","e","c","d","e","d","e","e"),
                  Var2 = c("a","a","a","a","a","b","b","b","b","c","c","c","d","d","e"),
                  pre = c(1,2,3,4,5,1,6,7,8,1,9,10,1,11,1) )

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