Predict with a subset of RF trees

predict_rf_subset.R

library("randomForest")
data(mtcars)

rf <- randomForest(mpg ~ ., data = mtcars, ntree = 10)
preds <- predict(rf, newdata = mtcars, predict.all = TRUE)

# Aggregate predictions 
preds$aggregate
# Invididual tree predictions
preds$individual 

predict_rf_subset <- function(model, newdata, subset, ...) {
  tree_p <- predict(model, newdata, predict.all = TRUE)$individual
  apply(tree_p[, subset], 1, mean)  # Mean prediction across subset trees
}

predict_rf_subset(rf, mtcars, c(1, 4, 7))