From 39586c8a709ada586275af88f3dc4f26174fc1a1 Mon Sep 17 00:00:00 2001
From: David Nabergoj <davidnabergoj4@gmail.com>
Date: Sun, 23 Jun 2024 19:28:26 +0200
Subject: [PATCH] Fix inverse and forward in squeeze

---
 .../bijections/finite/multiscale/base.py      | 65 ++-----------------
 1 file changed, 5 insertions(+), 60 deletions(-)

diff --git a/normalizing_flows/bijections/finite/multiscale/base.py b/normalizing_flows/bijections/finite/multiscale/base.py
index f073c62..fad40f7 100644
--- a/normalizing_flows/bijections/finite/multiscale/base.py
+++ b/normalizing_flows/bijections/finite/multiscale/base.py
@@ -75,33 +75,6 @@ def forward(self, x: torch.Tensor, context: torch.Tensor = None) -> Tuple[torch.
         batch_shape = get_batch_shape(x, self.event_shape)
         log_det = torch.zeros(*batch_shape, device=x.device, dtype=x.dtype)
 
-        channels, height, width = x.shape[-3:]
-        assert height % 2 == 0
-        assert width % 2 == 0
-        n_rows = height // 2
-        n_cols = width // 2
-        n_squares = n_rows * n_cols
-
-        square_mask = torch.kron(
-            torch.arange(n_squares).view(n_rows, n_cols),
-            torch.ones(2, 2)
-        )
-        channel_mask = torch.arange(n_rows * n_cols).view(n_rows, n_cols)[None].repeat(4 * channels, 1, 1)
-
-        # out = torch.zeros(size=(*batch_shape, self.squeezed_event_shape), device=x.device, dtype=x.dtype)
-        out = torch.empty(size=(*batch_shape, 4 * channels, height // 2, width // 2), device=x.device, dtype=x.dtype)
-
-        channel_mask = channel_mask.repeat(*batch_shape, 1, 1, 1)
-        square_mask = square_mask.repeat(*batch_shape, channels, 1, 1)
-        for i in range(n_squares):
-            out[channel_mask == i] = x[square_mask == i]
-
-        return out, log_det
-
-    def forward2(self, x, context=None):
-        batch_shape = get_batch_shape(x, self.event_shape)
-        log_det = torch.zeros(*batch_shape, device=x.device, dtype=x.dtype)
-
         channels, height, width = x.shape[-3:]
         assert height % 2 == 0
         assert width % 2 == 0
@@ -111,7 +84,7 @@ def forward2(self, x, context=None):
             x[..., ::2, 1::2],
             x[..., 1::2, ::2],
             x[..., 1::2, 1::2]
-        ], dim=1)
+        ], dim=-3)
         return out, log_det
 
     def inverse(self, z: torch.Tensor, context: torch.Tensor = None) -> Tuple[torch.Tensor, torch.Tensor]:
@@ -128,39 +101,11 @@ def inverse(self, z: torch.Tensor, context: torch.Tensor = None) -> Tuple[torch.
         height = 2 * half_height
         channels = four_channels // 4
 
-        n_rows = height // 2
-        n_cols = width // 2
-        n_squares = n_rows * n_cols
-
-        square_mask = torch.kron(
-            torch.arange(n_squares).view(n_rows, n_cols),
-            torch.ones(2, 2)
-        )
-        channel_mask = torch.arange(n_rows * n_cols).view(n_rows, n_cols)[None].repeat(4 * channels, 1, 1)
-        out = torch.empty(size=(*batch_shape, channels, height, width), device=z.device, dtype=z.dtype)
-
-        channel_mask = channel_mask.repeat(*batch_shape, 1, 1, 1)
-        square_mask = square_mask.repeat(*batch_shape, channels, 1, 1)
-        for i in range(n_squares):
-            out[square_mask == i] = z[channel_mask == i]
-
-        return out, log_det
-
-    def inverse2(self, z, context=None):
-        batch_shape = get_batch_shape(z, self.transformed_event_shape)
-        log_det = torch.zeros(*batch_shape, device=z.device, dtype=z.dtype)
-
-        four_channels, half_height, half_width = z.shape[-3:]
-        assert four_channels % 4 == 0
-        width = 2 * half_width
-        height = 2 * half_height
-        channels = four_channels // 4
-
         out = torch.empty(size=(*batch_shape, channels, height, width), device=z.device, dtype=z.dtype)
-        out[..., ::2, ::2] = z[..., 0, :, :]
-        out[..., ::2, 1::2] = z[..., 1, :, :]
-        out[..., 1::2, ::2] = z[..., 2, :, :]
-        out[..., 1::2, 1::2] = z[..., 3, :, :]
+        out[..., ::2, ::2] = z[..., 0:channels, :, :]
+        out[..., ::2, 1::2] = z[..., channels:2 * channels, :, :]
+        out[..., 1::2, ::2] = z[..., 2 * channels:3 * channels, :, :]
+        out[..., 1::2, 1::2] = z[..., 3 * channels:4 * channels, :, :]
         return out, log_det