For-loop generates all NULL values

[aronlindberg]

Debugging a function I have also started to write a key function here: https://github.com/aronlindberg/4cases_routines/blob/master/R/sna_stat_per_PR.R#L19-L23

When I run:

actor_graphs <- list() 
for (i in 1:length(actor_lists_merged))
{ 
actor_graphs[[i]] <- tryNULL(graph.edgelist(actor_lists_merged[[i]])) 
 }

I get all NULL values. However, when I try to step through manually it like so:

actor_graphs[[1]] <- tryNULL(graph.edgelist(actor_lists_merged[[1]])) 

and

actor_graphs[[2]] <- tryNULL(graph.edgelist(actor_lists_merged[[2]])) 

It works...I have encountered this type of error several times in other settings, and I can't understand what is going on. I have tried all combinations of [] and [[]], but this does not help. Can you help?

[arilamstein]

I am actually not able to reproduce this bug. Here is what I get after stepping thru the function:

> head(actor_graphs)
[[1]]
IGRAPH DN-- 8 55 -- 
+ attr: name (v/c)
+ edges (vertex names):
 [1] leocassarani->emboss     leocassarani->diegoviola leocassarani->pirj       leocassarani->jrbudnack  leocassarani->zhando     leocassarani->jrbudnack 
 [7] leocassarani->kungfumike leocassarani->zhando     leocassarani->zhando     leocassarani->nibua-r    emboss      ->diegoviola emboss      ->pirj      
[13] emboss      ->jrbudnack  emboss      ->zhando     emboss      ->jrbudnack  emboss      ->kungfumike emboss      ->zhando     emboss      ->zhando    
[19] emboss      ->nibua-r    diegoviola  ->pirj       diegoviola  ->jrbudnack  diegoviola  ->zhando     diegoviola  ->jrbudnack  diegoviola  ->kungfumike
[25] diegoviola  ->zhando     diegoviola  ->zhando     diegoviola  ->nibua-r    pirj        ->jrbudnack  pirj        ->zhando     pirj        ->jrbudnack 
[31] pirj        ->kungfumike pirj        ->zhando     pirj        ->zhando     pirj        ->nibua-r    jrbudnack   ->zhando     jrbudnack   ->jrbudnack 
[37] jrbudnack   ->kungfumike jrbudnack   ->zhando     jrbudnack   ->zhando     jrbudnack   ->nibua-r    zhando      ->jrbudnack  zhando      ->kungfumike
[43] zhando      ->zhando     zhando      ->zhando     zhando      ->nibua-r    jrbudnack   ->kungfumike jrbudnack   ->zhando     jrbudnack   ->zhando    
+ ... omitted several edges

[[2]]
NULL

[[3]]
NULL

[[4]]
NULL

[[5]]
NULL

[[6]]
IGRAPH DN-- 3 15 -- 
+ attr: name (v/c)
+ edges (vertex names):
 [1] jeremyz ->evanphx  jeremyz ->jeremyz  jeremyz ->dbussink jeremyz ->jeremyz  jeremyz ->dbussink evanphx ->jeremyz  evanphx ->dbussink evanphx ->jeremyz 
 [9] evanphx ->dbussink jeremyz ->dbussink jeremyz ->jeremyz  jeremyz ->dbussink dbussink->jeremyz  dbussink->dbussink jeremyz ->dbussink

Note that the lapply above the for loop creates a lot of errors for me

> actor_lists_merged <- lapply(actors_per_PR, combine_edge_lists)
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m
Error in combn(data, 2) : n < m