From 2538b4c5b8e2268da56765ed79f0b38206bbc82a Mon Sep 17 00:00:00 2001
From: Gregory Jefferis <jefferis@gmail.com>
Date: Sun, 18 Feb 2024 11:01:09 +0000
Subject: [PATCH] speed up xyzmatrix.list for arrow list-vectors

* for some reason base lengths is very slow in this case
* will use natcpp if available. Speed up is from 500 ms to 2 ms for 250k points
---
 R/xyzmatrix.R | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/R/xyzmatrix.R b/R/xyzmatrix.R
index aa7d9322..86b52308 100644
--- a/R/xyzmatrix.R
+++ b/R/xyzmatrix.R
@@ -102,7 +102,7 @@ xyzmatrix.list<-function(x, empty2na=TRUE, ...) {
   if(is.neuron(x,Strict=FALSE))
     return(xyzmatrix(x$d[,c("X","Y","Z")]))
   
-  lens=lengths(x)
+  lens=listlengths(x, use.names = F)
   if(!empty2na) {
     if(any(lens!=3))
       stop("xyzmatrix accepts lists where each element has 3 numbers!")
@@ -119,6 +119,16 @@ xyzmatrix.list<-function(x, empty2na=TRUE, ...) {
   xyzmatrix(mat)
 }
 
+# private function - motivated by the case that arrow lists of vectors
+# are extremely slow with base R lengths
+listlengths <- function(x, use.names = FALSE) {
+  if(use_natcpp() & !use.names) {
+    return(natcpp::c_listlengths(x))
+  }
+  lengths(x, use.names = use.names)
+}
+
+
 #' @export
 #' @rdname xyzmatrix
 xyzmatrix.character<-function(x, ...) {