How to make a list from a matrix with new row names

Question

old matrix with LULC (land use land change) data

	Water	Trees	Building
Water	20	80	60
Second	70	10	10
Building	10	10	30

To this is what I want it to look like Thank you

	Value
Water-Water	20
Water-Trees	70
Water-Building	10
Trees-Trees	10
Trees-Water	80
Trees-Building	10
Building-Water	10
Building-Trees	10
Building-Building	30

If the question this is marked as a duplicate of doesn't answer your question, it will be because you have row names that are being dropped. If you're using `data.table` set `keep.rownames = TRUE` and if you're using `tidyverse` use the `rownames_to_column()` function. If the output is still not as expected, edit your question to include a [`reproducible example`](https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example) of your data, e.g. using `dput(head(df))`. — SamR, Mar 23 '23 at 08:39

Merijn van Tilborg · Answer 1 · 2023-03-23T09:16:20.193

m <- matrix(c(20, 70, 10, 80, 10, 10, 60, 10, 30), 3, 3, dimnames = list(c("Water","Trees","Building"), c("Water","Trees","Building")))
            
library(tidyverse)

m %>% 
  as.data.frame.table %>%
  summarize(
    group = paste(Var1, Var2, sep = "-"),
    Value = Freq
  ) %>%
  column_to_rownames("group") %>%
  as.matrix # if you want the output to be a matrix again

                  Value
Water-Water          20
Trees-Water          70
Building-Water       10
Water-Trees          80
Trees-Trees          10
Building-Trees       10
Water-Building       60
Trees-Building       10
Building-Building    30

 num [1:9, 1] 20 70 10 80 10 10 60 10 30
 - attr(*, "dimnames")=List of 2
  ..$ : chr [1:9] "Water-Water" "Trees-Water" "Building-Water" "Water-Trees" ...
  ..$ : chr "Value"

How to make a list from a matrix with new row names

1 Answers1