plot_network example failure: class conditions and incompatibility with latest igraph

[kyleam]

Thanks for your work on this package.

When I try to build with R 4.1 from GERGM's master (ffb67f7), I see a failure related to a non-scalar condition:

* checking examples ... ERROR
Running examples in ‘GERGM-Ex.R’ failed
The error most likely occurred in:
> base::assign(".ptime", proc.time(), pos = "CheckExEnv")
> ### Name: plot_network
> ### Title: Plots of value-edged networks.
> ### Aliases: plot_network
>
> ### ** Examples
>
> set.seed(12345)
> sociomatrix <- matrix(rnorm(400,0,20),20,20)
> colnames(sociomatrix) <- rownames(sociomatrix) <- letters[1:20]
> plot_network(sociomatrix)
 ----------- FAILURE REPORT --------------
 --- failure: the condition has length > 1 ---
 --- srcref ---
:
 --- package (from environment) ---
GERGM
 --- call from context ---
plot_network(sociomatrix)
 --- call from argument ---
if (class(sociomatrix) != "matrix" & class(sociomatrix) != "data.frame") {
    stop("You must provide the network as a numeric matrix.")
}
 --- R stacktrace ---
where 1: plot_network(sociomatrix)
 --- value of length: 2 type: logical ---
[1] FALSE  TRUE
 --- function from context ---

If I resolve that and a related issue with the following patch...

diff --git a/R/plot_network.R b/R/plot_network.R
index 0569e38..63f7fad 100644
--- a/R/plot_network.R
+++ b/R/plot_network.R
@@ -55,7 +55,7 @@ plot_network <- function(sociomatrix,

   par(mar = c(1,0,1,0))
   # check input
-  if (class(sociomatrix) != "matrix" & class(sociomatrix) != "data.frame") {
+  if (!inherits(sociomatrix, c("matrix", "data.frame"))) {
     stop("You must provide the network as a numeric matrix.")
   }

@@ -90,8 +90,7 @@ plot_network <- function(sociomatrix,
     }

     # check optional input
-    if (class(comparison_network) != "matrix" &
-       class(comparison_network) != "data.frame") {
+    if (!inherits(comparison_network, c("matrix", "data.frame"))) {
       stop("You must provide the network as a numeric matrix.")
     }

... I hit into another error in the same example:

❯ checking examples ... ERROR
  Running examples in ‘GERGM-Ex.R’ failed
  The error most likely occurred in:

  > base::assign(".ptime", proc.time(), pos = "CheckExEnv")
  > ### Name: plot_network
  > ### Title: Plots of value-edged networks.
  > ### Aliases: plot_network
  >
  > ### ** Examples
  >
  > set.seed(12345)
  > sociomatrix <- matrix(rnorm(400,0,20),20,20)
  > colnames(sociomatrix) <- rownames(sociomatrix) <- letters[1:20]
  > plot_network(sociomatrix)
  Error in igraph::layout_with_fr(net, weights = igraph::E(net)$weight) :
    At core/layout/fruchterman_reingold.c:401 : Weights must be positive for Fruchterman-Reingold layout. Invalid value
  Calls: plot_network -> <Anonymous>
  Execution halted

That failure is with igraph 1.3.4, which was published 2022-07-19. If I try with 1.3.3, I see the same failure. The failure goes away with 1.3.2.

Perhaps igraph got stricter in its checks and the example just needs to be updated to use more realistic input?