Setting an attribute to `NULL` fails

[krlmlr]

library(igraph, warn.conflicts = FALSE)

g <- make_ring(10)
V(g)$name <- paste0("v", 1:10)
V(g)$name <- NULL
#> Error in `V<-`(`*tmp*`, value = structure(1:10, names = c("v1", "v2", : invalid indexing

^{Created on 2025-06-26 with reprex v2.1.1}

[krlmlr]

@claude: Please fix and check that the fix actually works, and propose a PR.

[github-actions]

Claude finished @krlmlr's task —— View job

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Fixing NULL Attribute Assignment Bug

Working on fixing the issue where setting V(g)$name <- NULL fails with an invalid indexing error.

Todo List:

• Analyze the codebase structure and locate relevant files
• Reproduce the bug locally
• Identify the root cause in the V<- assignment operator
• Fix the bug to handle NULL assignment properly
• Test the fix with the provided example
• Check for existing tests and add/update as needed
• Commit changes and create PR

Root Cause Found:
The issue is in the $<-.igraph.vs function at /R/iterators.R:1316. When setting V(g)$name <- NULL, the function does attr(x, "value") <- value where value is NULL. In R, setting an attribute to NULL removes the attribute entirely rather than setting it to NULL.

Then, the V<- operator checks for the presence of both "name" and "value" attributes. Since the "value" attribute was removed, it throws "invalid indexing" error.

The fix is to handle NULL values properly in the $<-.igraph.vs function.

[szhorvat]

@krlmlr Is using Claude this way an open service or does it requires a subscription tied to a GitHub username?

[krlmlr]

It will only react to requests by maintainers. We are paying for the tokens. For reference, this PR came out at about USD 1.50 . Investigating more cost-effective options.

[krlmlr]

Uh, and it's not even a PR. Need to install an app.

[krlmlr]

@claude: Create a PR.

[github-actions]

Claude finished @krlmlr's task —— View job

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Creating PR for NULL Attribute Assignment Fix

Working on creating a PR to fix the issue where setting V(g)$name <- NULL fails with an invalid indexing error.

Todo List:

• Set up R environment and install dependencies
• Reproduce the bug locally
• Examine the problematic code in /R/iterators.R
• Implement the fix for NULL handling
• Test the fix with the provided example
• Check for existing tests and update if needed
• Run linting/testing if available
• Commit changes to branch
• Provide PR creation link

Root Cause Found:
The issue affects both $<-.igraph.vs (line 1311) and $<-.igraph.es (line 1326) functions in /R/iterators.R. When setting V(g)$name <- NULL, the function does attr(x, "value") <- value where value is NULL. In R, setting an attribute to NULL removes the attribute entirely rather than setting it to NULL.

Then, the V<- (line 1337) and E<- (line 1361) operators check for the presence of both "name" and "value" attributes. Since the "value" attribute was removed, they throw "invalid indexing" error.

Fix: Modify both attribute assignment functions to handle NULL values properly by preserving the "value" attribute when NULL is assigned.

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[maelle]

Because of #2006 I would like to discuss this again.