在 R 中变换矩阵答案

【问题标题】：Transforming Matrix in R在 R 中变换矩阵
【发布时间】：2021-05-11 12:56:23
【问题描述】：

我目前在将矩阵转换为以下格式时遇到问题。如何以最简单的方式在 R 中实现这一点？理想情况下，我想将第二个矩阵用作数据框。非常感谢！

      Estonia Germany Poland
Estonia 0       2       3
Germany 2       0       4
 Poland  3      4       0


Country1      Country2     Weight
Estonia       Estonia        0
Estonia       Germany        2
Estonia       Poland         3
Germany       Estonia        2
...

【问题讨论】：

标签： r dataframe matrix tidyverse data-transform

【解决方案1】：

如果矩阵被称为mat，你可以使用：

library(tibble)
library(tidyr)

mat %>%
  as.data.frame() %>%
  rownames_to_column('Country1') %>%
  pivot_longer(cols = -Country1, names_to = 'Country2', values_to = 'Weight')

#  Country1 Country2 Weight
#  <chr>    <chr>     <int>
#1 Estonia  Estonia       0
#2 Estonia  Germany       2
#3 Estonia  Poland        3
#4 Germany  Estonia       2
#5 Germany  Germany       0
#6 Germany  Poland        4
#7 Poland   Estonia       3
#8 Poland   Germany       4
#9 Poland   Poland        0

数据

mat <- structure(c(0L, 2L, 3L, 2L, 0L, 4L, 3L, 4L, 0L), .Dim = c(3L, 
3L), .Dimnames = list(c("Estonia", "Germany", "Poland"), c("Estonia", 
"Germany", "Poland")))

【讨论】：

【解决方案2】：

另一种非tidyverse方式：

df <- as.data.frame(as.table(mat))
names(df) <- c("Country1", "Country2", "Weight")
df
#   Country1 Country2 Weight
# 1  Estonia  Estonia      0
# 2  Germany  Estonia      2
# 3   Poland  Estonia      3
# 4  Estonia  Germany      2
# 5  Germany  Germany      0
# 6   Poland  Germany      4
# 7  Estonia   Poland      3
# 8  Germany   Poland      4
# 9   Poland   Poland      0

【讨论】：

【解决方案3】：

我们可以使用melt

library(reshape2)
melt(mat)

数据

mat <- structure(c(0L, 2L, 3L, 2L, 0L, 4L, 3L, 4L, 0L), .Dim = c(3L, 
3L), .Dimnames = list(c("Estonia", "Germany", "Poland"), c("Estonia", 
"Germany", "Poland")))

【讨论】：

【解决方案4】：

另一个基本 R 选项

> cbind(expand.grid(dimnames(mat)), Weight = c(mat))
     Var1    Var2 Weight
1 Estonia Estonia      0
2 Germany Estonia      2
3  Poland Estonia      3
4 Estonia Germany      2
5 Germany Germany      0
6  Poland Germany      4
7 Estonia  Poland      3
8 Germany  Poland      4
9  Poland  Poland      0

【讨论】：