Blog focal method produces plot showing only bottom half of the study area about blog_tips

[statnmap]

You need to define what to do when all values are the same in the focal window. Sometimes you have something like this : cor(rep(1, 3), rep(1, 3)).
If you consider that all values the same means that correlation is 1, then you can use this function:

     focal_cor = focal(
         x = a_b_nb,
         w = matrix(1, 5, 5),
         # fun = function(x, y = a_b_stack){ # Original
         # cor(values(y)[x, 1], values(y)[x, 2], # Original
         # use = "na.or.complete")
         # },
         
         fun = function(x, y = matrix_a_b){ # [MW]
           # If all values the same
           if (isTRUE(var(y[x, 1], y[x, 2], # [MW]
                   use = "na.or.complete") == 0)) {
             return(1)
           }
           cor(y[x, 1], y[x, 2], # [MW]
               use = "na.or.complete")
         },
         filename = file.path("~/focal_cor.tif"),
         overwrite = TRUE
       )

Then you can play with w = matrix(1, 3, 3) in focal(); use and method in cor()

[statnmap]

Note that you can use {cartomisc} for gplot_data(), which is lighter than {SDMSelect}:
https://statnmap.github.io/cartomisc/

# remotes::install_github("statnmap/cartomisc")
cartomisc::gplot_data()

[Saadi4469]

Thank you so much for your guidance.

Cheers