I’ve created a function to compute an out-of-bag proximity matrix of a ranger object, based on `edarf::extract_proximity`

:

```
extract_proximity_oob = function(fit, olddata) {
pred = predict(fit, olddata, type = "terminalNodes")$predictions
prox = matrix(NA, nrow(pred), nrow(pred))
ntree = ncol(pred)
n = nrow(prox)
if (is.null(fit$inbag.counts)) {
stop("call ranger with keep.inbag = TRUE")
}
# Get inbag counts
inbag = simplify2array(fit$inbag.counts)
for (i in 1:n) {
for (j in 1:n) {
# Use only trees where both obs are OOB
tree_idx = inbag[i, ] == 0 & inbag[j, ] == 0
prox[i, j] = sum(pred[i, tree_idx] == pred[j, tree_idx]) / sum(tree_idx)
}
}
prox
}
```

(taken from https://github.com/imbs-hl/ranger/issues/234)