Add transpose_zx and z_slice3 functions to MRI.

diff --git a/src/MRI.hs b/src/MRI.hs
index 2dd6f6592e6e3bb7ac8d1eefbe73a4764e3cf787..52be3f7b1cba92c96d9bb64142ed7b3dd4acb546 100644 (file)
--- a/src/MRI.hs
+++ b/src/MRI.hs
@@ -139,3 +139,22 @@ blue_dbl_data =
 z_slice :: Elt a => Int -> Array DIM3 a -> Array DIM2 a
 z_slice n arr =
   slice arr (Any :. n :. All :. All)
+
+
+transpose_zx :: Elt a => Array DIM3 a -> Array DIM3 a
+transpose_zx arr =
+  traverse arr
+           (\(Z :. zdim :. ydim :. xdim) -> (Z :. xdim :. ydim :. zdim))
+           (\_ -> (\(Z :. z :. y :. x) -> arr ! (Z :. x :. y :. z)))
+
+
+z_slice3 :: Elt a => Int -> Array DIM3 a -> Array DIM3 a
+z_slice3 n arr
+  | n == 0 = transpose_zx $ current R.++ next
+  | n == zdim-1 = transpose_zx $ previous R.++ current
+  | otherwise = transpose_zx $ previous R.++ current R.++ next
+  where
+    (Z :. zdim :. _ :. _) = extent arr
+    previous = transpose_zx $ reshape mri_slice3d (z_slice (n-1) arr)
+    current = transpose_zx $ reshape mri_slice3d (z_slice n arr)
+    next = transpose_zx $ reshape mri_slice3d (z_slice (n+1) arr)