From 6ff45fe556d3b49a1506c5882036f909c143ed85 Mon Sep 17 00:00:00 2001
From: Connor Moore <connor@hhmoore.ca>
Date: Fri, 27 Feb 2026 14:08:37 -0500
Subject: Split up some modules and added a testing class for sectors

---
 class/mod_sectors.f90 | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 class/mod_sectors.f90

(limited to 'class/mod_sectors.f90')

diff --git a/class/mod_sectors.f90 b/class/mod_sectors.f90
new file mode 100644
index 0000000..d32a75a
--- /dev/null
+++ b/class/mod_sectors.f90
@@ -0,0 +1,65 @@
+module sectors
+use globals
+implicit none
+contains
+
+subroutine ONETO2(id, box_size, x, y)
+    implicit none
+    integer, intent(in)  :: id
+    integer, intent(in)  :: box_size
+    integer, intent(out) :: x, y
+
+    y = id / box_size
+    x = mod(id, box_size)
+end subroutine ONETO2
+
+function TWOtoONE(x, y, box_size) result(id)
+    implicit none
+    integer, intent(in) :: x, y, box_size
+    integer :: id
+
+    id = y * box_size + x
+end function TWOtoONE
+
+function get_neighbour_ids(p, N) result (neighbours)
+    integer, intent(in) :: p !> The sequential position
+    integer, intent(in) :: N !> The grid size (i.e., NxN sectors)
+    integer, allocatable, dimension(:) :: neighbours !> The list of neighbours
+    integer :: i,j,k
+    integer :: x_cell, y_cell, x_test, y_test
+    integer :: max_list(9)
+
+    !> Don't save the values between calls
+    k = 1
+    max_list = -1
+
+    call ONETO2(p,N,x_cell,y_cell)
+    max_list(k) = p
+
+    !print *, max_list
+
+    !> Start by just getting all of the neighbours
+    do i = -1,1
+        do j = -1,1
+            if(i == 0 .and. j == 0) cycle !> Skip the cell itself
+            
+            !> The "test" coordinate
+            x_test = x_cell + i
+            y_test = y_cell + j
+
+            !> If the coordinates are real (within the expected range), add them to the list:
+            if((x_test .ge. 0 .and. x_test .lt. N) .and. (y_test .ge. 0 .and. y_test .lt. N)) then
+                !> Increment the number of correct coordinates
+                k = k + 1
+                !> Flip a zero to the new coordinate in the max list
+                max_list(k) = TWOtoONE(x_test, y_test, N)
+            end if
+        end do
+    end do
+
+    !> Return a vector of all non-zero elements
+    neighbours = pack(max_list, max_list>= 0.0)
+
+end function get_neighbour_ids
+    
+end module sectors
-- 
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