Error in mgmsampler function

[LiuJL1100]

Hi Jonas,

I run the exampling code in the documantation of mgmsampler function, but got the warning message:

Error in if (!(class(interactions[[i]][[row]]) %in% c("array", "matrix"))) stop("The parameters of each interaction have to be provided as k-dimensional array.") : 
  the condition has length > 1

How to slove this problem?

[Jiahao-ZHU]

I also came across this problem.

My mgm version is "1.2-14", R version is "4.3.2 (2023-10-31)", and RStudio version is "2023.09.1+494"

When I ran example 1 in the mgmsampler() function, I got the same warning message. However, sexamples 2 and 3 (focus on 3-way interaction) are fine. I wonder if there is any problem with 2-way interaction or else.

Hoping for solutions. Thanks.

[Jiahao-ZHU]

I went through the code of the function, and I think this problem might occur because the code: f (!(class(interactions[[i]][[row]]) %in% c("array", "matrix"))) in

for (i in 1:n_order) { n_ints <- length(interactions[[i]]) if (n_ints > 0) for (row in 1:n_ints) if (!(class(interactions[[i]][[row]]) %in% c("array", "matrix"))) stop("The parameters of each interaction have to be provided as k-dimensional array.") }

returns more than one logic element (as for example 1, the result is TRUE TRUE). Therefore, the condition has length > 1.

To solve this problem, I defined a new function mgm_sampler on my own, and replaced the original code with
for(i in 1:n_order) { n_ints <- length(interactions[[i]]) if(n_ints > 0) { for(row in 1:n_ints) { if(!inherits(interactions[[i]][[row]], "array") && !inherits(interactions[[i]][[row]], "matrix")) { stop("The parameters of each interaction have to be provided as k-dimensional array.") } } } }

Hope this solution can help. :)

[TomRow90]

Hello,

I was hoping to use this for some simulations I need to run. I just installed the latest developmental version and it looks like this error is still present (it was still present in the CRAN version as well). I tried the workaround posted by Jiahao-ZHU above but I can't quite get that to work. So I was just wondering whether anyone has found another workaround or whether an update to the developmental version could be made? Many thanks.

[jmbh]

I'll try to fix this asap. Meanwhile, an alternative and possibly more convenient way to simulate data with multivariate dependencies between variables with different domains is to simulate from a DAG. This avoids the issues arising from needing a proper joint distribution over all variables (see Appendix F in https://osf.io/preprints/psyarxiv/926pv and the accompanying code in corresponding reproducibility repo).

[TomRow90]

Great, thanks Jonas, and for the tip and link as well.

[jmbh]

I know this has been a while, but any chance yo could send me a reproducible example of this?

[TomRow90]

Hi Jonas, Apologies for my slow reply. The error message happens if you run Example 1 in the mgmsampler help material if that gives you what you need? Kind regards, Tom Rowland PhD student in Animal Behaviour and Welfare University of Lincoln Animal Behaviour, Cognition, and Welfare Research Group

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