how to fill in certain values where rowname and column name are identical

user_7500268 0
Viewed 90

Suppose I have a data frame as follows:

dat <- data.frame(
  ee=1:4,
  bb = 4:7,
  cc =4:7,
  dd = 2:5
)  
rownames(dat) <- colnames(dat)
dat
   ee bb cc dd
ee  1  4  4  2
bb  2  5  5  3
cc  3  6  6  4
dd  4  7  7  5

How can I replace the cell value to 1 where column and row names are the same? also suppose that the position may not in the diagonal the position needing replacement can occur in an arbitrary position.

dataframe r
3 Answers

This surprisingly works for a data frame:

diag(dat) <- 1

But guess what, diag(dat) does not work.

user_48917380

To answer the general question 'How can I replace the cell value where column and row names are the same?' for arbitrary column positions use match() (I replaced by 9 to make the point)

dat <- data.frame(
  ee = 1:4,
  bb = 4:7,
  cc = 4:7,
  dd = 2:5
)  
set.seed(1157)
rownames(dat) <- sample(colnames(dat))
dat
#>    ee bb cc dd
#> dd  1  4  4  2
#> ee  2  5  5  3
#> cc  3  6  6  4
#> bb  4  7  7  5


replace_index <- cbind(row = 1:nrow(dat), column= match(rownames(dat), colnames(dat)))
replace_index
#>      row column
#> [1,]   1      4
#> [2,]   2      1
#> [3,]   3      3
#> [4,]   4      2

dat[replace_index] <- 9
dat
#>    ee bb cc dd
#> dd  1  4  4  9
#> ee  9  5  5  3
#> cc  3  6  9  4
#> bb  4  9  7  5

Created on 2022-08-16 by the reprex package (v2.0.1)

user_197495250

Identify the common names and assign the value. Try this:

imhere <- rownames(dat)[rownames(dat) %in% colnames(dat)]

for (i in imhere) dat[i,i] <- 999
user_25618430
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