## Issue

I have a matrix in `R`

, namely `dat`

, and I am trying to create a information matrix using the `infotheo`

package between all variable combinations. This is the code:

```
set.seed(1234)
m <- 10
n <- 5
dat <- round(matrix(runif(m * n), m, n))
library(infotheo)
a = combn(seq(ncol(dat)), 2, function(x)condinformation(dat[, x[1]], dat[,x[2]], method = 'emp'))
b <- structure(a, Size = ncol(dat), class = 'dist')
b <- as.matrix(b)
```

which result in the following:

```
> b
1 2 3 4 5
1 0.000000000 0.004021743 0.06326870 0.19497599 0.004021743
2 0.004021743 0.000000000 0.03218930 0.01384429 0.291103166
3 0.063268705 0.032189301 0.00000000 0.01384429 0.013844294
4 0.194975994 0.013844294 0.01384429 0.00000000 0.032189301
5 0.004021743 0.291103166 0.01384429 0.03218930 0.000000000
```

My problem is that while all values are correct, i.e.,`condinformation(dat[, 1], dat[,2],method = 'emp')=0.004021743`

, the diagonal elements are incorrect. For example

```
> condinformation(dat[, 1], dat[,1],method = 'emp')
[1] 0.6108643
```

what I am doing wrong in my code and get this result? Do you have an alternative solution for the desired outcome?

## Solution

As det mentioned, `combn`

won’t do (1, 1), (2, 2), etc. Try this instead.

```
b <- matrix(0, n, n)
b[lower.tri(b, TRUE)] <- combn(seq(n + 1), 2, function(x) condinformation(dat[, x[1]], dat[,x[2] - 1], method = 'emp'))
b[upper.tri(b)] <- b[lower.tri(b)]
```

Answered By – jblood94

Answer Checked By – Dawn Plyler (BugsFixing Volunteer)