Avg. dist to knn in second dataset

[nlebovits]

Is there a quick way of calculating knn distance from one set of points to another? i.e., I have pts and otherPts and for each point in pts want to calculate the average distance to knn in otherPoints. Current use case is an assignment for home sale price prediction in Public Policy Analytics in which we're asked, among other potential features, to consider the average distance to k nearest crimes.

Current custom function proposed by our textbook is:

nn_function <- function(measureFrom,measureTo,k) {
  measureFrom_Matrix <-
    as.matrix(measureFrom)
  measureTo_Matrix <-
    as.matrix(measureTo)
  nn <-   
    get.knnx(measureTo, measureFrom, k)$nn.dist
  output <-
    as.data.frame(nn) %>%
    rownames_to_column(var = "thisPoint") %>%
    gather(points, point_distance, V1:ncol(.)) %>%
    arrange(as.numeric(thisPoint)) %>%
    group_by(thisPoint) %>%
    summarize(pointDistance = mean(point_distance)) %>%
    arrange(as.numeric(thisPoint)) %>% 
    dplyr::select(-thisPoint) %>%
    pull()
  
  return(output)  
}