From 9725890536311dae2c3c8a28e9a8ac1184e20084 Mon Sep 17 00:00:00 2001
From: yaraskaf <56359026+yaraskaf@users.noreply.github.com>
Date: Tue, 28 Apr 2020 14:25:44 -0400
Subject: [PATCH] fix(BallCover): add check for missing index to BallCover.R

Checking for null/missing index reduces the number of times the cover constructs self$level_sets, speeding up the cover.
---
 R/BallCover.R | 63 +++++++++++++++++++++++++++------------------------
 1 file changed, 33 insertions(+), 30 deletions(-)

diff --git a/R/BallCover.R b/R/BallCover.R
index c71942c..7774d06 100644
--- a/R/BallCover.R
+++ b/R/BallCover.R
@@ -1,10 +1,10 @@
 #' Ball Cover
 #'
 #' @docType class
-#' @description This class provides a cover whose open sets are formed by the union of \deqn{\epsilon}-balls centered 
+#' @description This class provides a cover whose open sets are formed by the union of \deqn{\epsilon}-balls centered
 #' about each point. Using this class requires the \code{RANN} package to be installed, and thus explicitly assumes
-#' the filter space endowed with the euclidean metric. 
-#' 
+#' the filter space endowed with the euclidean metric.
+#'
 #' @field epsilon := radius of the ball to form around each point
 #' @author Matt Piekenbrock
 #' @export
@@ -41,33 +41,36 @@ BallCover$set("public", "construct_cover", function(filter, index=NULL){
     stop("Package \"RANN\" is needed for to use this cover.", call. = FALSE)
   }
   self$validate()
-  
-  ## Get filter values 
-  fv <- filter()
-  f_dim <- ncol(fv)
-  f_size <- nrow(fv)
-  
-  ## Construct the balls
-  ball_cover  <- RANN::nn2(fv, query = fv, searchtype = "radius", radius = self$epsilon)
-  
-  ## Union them together 
-  ds <- union_find(f_size)
-  apply(ball_cover$nn.idx, 1, function(idx){
-    connected_idx <- idx[idx != 0] - 1L
-    if (length(connected_idx) > 0){
-      ds$union_all(connected_idx)
-    }
-  })
-  
-  ## Construct the intersections between the open sets and the data
-  cc <- ds$connected_components()
-  self$index_set <- as.character(unique(cc))
-  ls <- lapply(self$index_set, function(idx){
-    which(cc == as.integer(idx))
-  })
-  self$level_sets <- structure(ls, names=self$index_set)
+
+  if(missing(index) || is.null(index)){
+    ## Get filter values
+    fv <- filter()
+    f_dim <- ncol(fv)
+    f_size <- nrow(fv)
+
+    ## Construct the balls
+    ball_cover  <- RANN::nn2(fv, query = fv, searchtype = "radius", radius = self$epsilon)
+
+    ## Union them together
+    ds <- union_find(f_size)
+    apply(ball_cover$nn.idx, 1, function(idx){
+      connected_idx <- idx[idx != 0] - 1L
+      if (length(connected_idx) > 0){
+        ds$union_all(connected_idx)
+      }
+    })
+
+    ## Construct the intersections between the open sets and the data
+    cc <- ds$connected_components()
+    self$index_set <- as.character(unique(cc))
+    ls <- lapply(self$index_set, function(idx){
+      which(cc == as.integer(idx))
+    })
+
+    self$level_sets <- structure(ls, names=self$index_set)
+  }
   if (!missing(index)){ return(self$level_sets[[index]]) }
-  
-  ## Always return self 
+
+  ## Always return self
   invisible(self)
 })