From 1d41984ada6e7c4d89128881a5ef3220ed596519 Mon Sep 17 00:00:00 2001
From: Gregory Jefferis <jefferis@gmail.com>
Date: Tue, 29 Sep 2020 09:36:05 +0100
Subject: [PATCH] Fix neuprint_connection_table when 0 connections

* closes #135
---
 R/connectivity.R | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/R/connectivity.R b/R/connectivity.R
index 7270429c..3775977a 100644
--- a/R/connectivity.R
+++ b/R/connectivity.R
@@ -270,7 +270,11 @@ neuprint_connection_table <- function(bodyids,
   }
   d <- neuprint_list2df(nc, return_empty_df = TRUE)
   d$weight <- as.integer(d$weight)
-  d$prepost <-  ifelse(prepost=="PRE",0,1)
+  if(nrow(d)==0) {
+    d$prepost=integer(length = 0L)
+  } else {
+    d$prepost <-  ifelse(prepost=="PRE",0,1)
+  }
   if(!is.null(roi)){
     d <- d[d$roi%in%roi,]
   }