transform_grayscale not implemented for torch_tensor error

[Mariusz Musiał]

Hi,

trying to load and transform png images using load_image function based on one of torchvision's vignettes

load_image <- function(path) {
    x <- png::readPNG(path) %>%
        transform_to_tensor() %>%
        transform_grayscale(num_output_channels = 1) %>% 
        transform_resize(c(105, 105))
    x <- x[newaxis,..]
}

but getting this error:

Error in `not_implemented_error()`:
! not implemented for torch_tensor
• not implemented for R7

> sessionInfo()
R version 4.2.0 (2022-04-22)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS Monterey 12.4

Matrix products: default
LAPACK: /Library/Frameworks/R.framework/Versions/4.2/Resources/lib/libRlapack.dylib

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
 [1] forcats_0.5.1          stringr_1.4.0          dplyr_1.0.9            purrr_0.3.4            readr_2.1.2           
 [6] tidyr_1.2.0            tibble_3.1.7           ggplot2_3.3.6          tidyverse_1.3.1        torchvision_0.4.1.9000
[11] torch_0.7.2           

loaded via a namespace (and not attached):
 [1] httr_1.4.3        pkgload_1.2.4     bit64_4.0.5       vroom_1.5.7       jsonlite_1.8.0    modelr_0.1.8      brio_1.1.3       
 [8] assertthat_0.2.1  cellranger_1.1.0  remotes_2.4.2     sessioninfo_1.2.2 pillar_1.7.0      backports_1.4.1   glue_1.6.2       
[15] rvest_1.0.2       colorspace_2.0-3  pkgconfig_2.0.3   devtools_2.4.3    broom_0.8.0       magick_2.7.3      haven_2.5.0      
[22] scales_1.2.0      processx_3.5.3    tzdb_0.3.0        generics_0.1.2    usethis_2.1.5     ellipsis_0.3.2    cachem_1.0.6     
[29] withr_2.5.0       cli_3.3.0         magrittr_2.0.3    crayon_1.5.1      readxl_1.4.0      memoise_2.0.1     ps_1.7.0         
[36] fs_1.5.2          fansi_1.0.3       xml2_1.3.3        pkgbuild_1.3.1    tools_4.2.0       prettyunits_1.1.1 hms_1.1.1        
[43] lifecycle_1.0.1   munsell_0.5.0     reprex_2.0.1      callr_3.7.0       compiler_4.2.0    rlang_1.0.2       grid_4.2.0       
[50] rstudioapi_0.13   rappdirs_0.3.3    testthat_3.1.4    gtable_0.3.0      DBI_1.1.2         curl_4.3.2        R6_2.5.1         
[57] lubridate_1.8.0   fastmap_1.1.0     bit_4.0.4         utf8_1.2.2        rprojroot_2.0.3   coro_1.0.2        desc_1.4.1       
[64] stringi_1.7.6     parallel_4.2.0    Rcpp_1.0.8.3      png_0.1-7         vctrs_0.4.1       dbplyr_2.1.1      tidyselect_1.1.2