Help: Error message "length of NULL cannot be changed"

Usage
#1

When trying to generate colors or change the weight of edges when using igraph I’m generating the error “length of NULL cannot be changed.”

Specifically when running these codes:

    colrs <- c("skyblue", "orchid2", "peachpuff")
    V(net)$color <- colrs[V(net)$source]

I get:

Warning message:
In length(vattrs[[name]]) <- vc : length of NULL cannot be changed

When I run the code:

E(net)$width <- E(net)$weight/6

I get the same error. Has anyone gotten similar errors and know what to do with them in this context? Thank you

1 Like
#2

I am unable reproduce your problem. Please post a minimal working example of your problem. Perhaps it would then be possible to identify the problem.

#3

Were you able to identify a solution to this issue?

#4

@bimaben As stated above, in order to help, we need a minimal example that demonstrates the problem. See here for guidance: How to create a Minimal, Reproducible Example - Help Center - Stack Overflow

#5

Try.

net          <- graph_from_literal(A-B, A-C)
colrs        <- c("skyblue", "orchid2", "peachpuff") 
V(net)$color <- colrs[V(net)$source]
V(net)$color <- character(0)
E(net)$width <- E(net)$weight/6
E(net)$width <- numeric(0)

These error messages occur because V(g)$color and E(g)$weight do not exists and dependent expressions are coerced to character(0) and numeric(0) respectively.