[R] Unexpected result after auto-attaching of the Matrix package

[H B]

Hi Jeff,

you are obviously right and I would usually load packages before, but in
this case it was a saved R object that I had not created, and therefore
did not know what to expect.

I was prepared to get an error message, but not getting an error or at
least a warning and then getting the wrong result was kind of unexpected.

Best regards

Hilmar

On 12.02.25 03:02, Jeff Newmiller wrote:
> Why aren't you loading the package before you load the object that assumes the relevant methods for that object are available?
>
> On February 11, 2025 4:51:48 AM PST, H B via R-help <r-help using r-project.org> wrote:
>> Dear all,
>>
>> I just stumbled on this behavior - not sure if this is expected:
>>
>> R version 4.4.2 (2024-10-31) -- "Pile of Leaves"
>> Copyright (C) 2024 The R Foundation for Statistical Computing
>> Platform: x86_64-pc-linux-gnu
>>
>>> library(Matrix)
>>> sparseMatrix(i=1:10, j=1:10, x=rnorm(10)) |>
>> saveRDS("~/Downloads/sparsemat_test.rds")
>>> q()
>> Save workspace image? [y/n/c]: n
>> # start R again
>>> d <- readRDS("~/Downloads/sparsemat_test.rds")
>>> class(d)
>> [1] "dgCMatrix"
>> attr(,"package")
>> [1] "Matrix"
>>> dim(d)
>> Loading required package: Matrix
>> NULL
>>> dim(d)
>> [1] 10 10
>>
>> So the first call to dim(d) loads/attaches the Matrix package but
>> returns NULL for the call. Only the second call to dim returns the
>> correct results. I would expect the first call to succeed also,
>> otherwise what is the purpose of loading the package?
>>
>> Best regards
>>
>> Hilmar
>>
>>
>>> sessionInfo()
>> R version 4.4.2 (2024-10-31)
>> Platform: x86_64-pc-linux-gnu
>> Running under: Ubuntu 24.04.1 LTS
>>
>> Matrix products: default
>> BLAS:   /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.12.0
>> LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.12.0
>>
>> locale:
>>   [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
>>   [3] LC_TIME=de_DE.UTF-8        LC_COLLATE=en_US.UTF-8
>>   [5] LC_MONETARY=de_DE.UTF-8    LC_MESSAGES=en_US.UTF-8
>>   [7] LC_PAPER=de_DE.UTF-8       LC_NAME=C
>>   [9] LC_ADDRESS=C               LC_TELEPHONE=C
>> [11] LC_MEASUREMENT=de_DE.UTF-8 LC_IDENTIFICATION=C
>>
>> time zone: Europe/Berlin
>> tzcode source: system (glibc)
>>
>> attached base packages:> sessionInfo()
>> R version 4.4.2 (2024-10-31)
>> Platform: x86_64-pc-linux-gnu
>> Running under: Ubuntu 24.04.1 LTS
>>
>> Matrix products: default
>> BLAS:   /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.12.0
>> LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.12.0
>>
>> locale:
>>   [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
>>   [3] LC_TIME=de_DE.UTF-8        LC_COLLATE=en_US.UTF-8
>>   [5] LC_MONETARY=de_DE.UTF-8    LC_MESSAGES=en_US.UTF-8
>>   [7] LC_PAPER=de_DE.UTF-8       LC_NAME=C
>>   [9] LC_ADDRESS=C               LC_TELEPHONE=C
>> [11] LC_MEASUREMENT=de_DE.UTF-8 LC_IDENTIFICATION=C
>>
>> time zone: Europe/Berlin
>> tzcode source: system (glibc)
>>
>> attached base packages:
>> [1] stats     graphics  grDevices utils     datasets  methods base
>>
>> other attached packages:
>> [1] Matrix_1.7-2
>>
>> loaded via a namespace (and not attached):
>> [1] compiler_4.4.2 grid_4.4.2     lattice_0.22-5
>>
>> [1] stats     graphics  grDevices utils     datasets  methods base
>>
>> other attached packages:
>> [1] Matrix_1.7-2
>>
>> loaded via a namespace (and not attached):
>> [1] compiler_4.4.2 grid_4.4.2     lattice_0.22-5
>>
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