Fix two power spectrum bugs about freq shift and flatten

map2map/models/power.py

@@ -18,32 +18,30 @@ def power(x):
 
     x = torch.rfft(x, signal_ndim)
     P = x.pow(2).sum(dim=-1)
-    del x
-
-    batch_ndim = P.dim() - signal_ndim - 1
-    if batch_ndim > 0:
-        P = P.mean(tuple(range(batch_ndim)))
-    if P.dim() > signal_ndim:
+    P = P.mean(dim=0)
     P = P.sum(dim=0)
-    P = P.flatten()
+    del x
 
     k = [torch.arange(d, dtype=torch.float32, device=P.device)
          for d in P.shape]
+    k = [j - len(j) * (j > len(j) // 2) for j in k[:-1]] + [k[-1]]
     k = torch.meshgrid(*k)
     k = torch.stack(k, dim=0)
     k = k.norm(p=2, dim=0)
-    k = k.flatten()
 
     N = torch.full_like(P, 2, dtype=torch.int32)
     N[..., 0] = 1
     if even:
         N[..., -1] = 1
+
+    k = k.flatten()
+    P = P.flatten()
     N = N.flatten()
 
     kbin = k.ceil().to(torch.int32)
     k = torch.bincount(kbin, weights=k * N)
     P = torch.bincount(kbin, weights=P * N)
-    N = torch.bincount(kbin, weights=N)
+    N = torch.bincount(kbin, weights=N).round().to(torch.int32)
     del kbin
 
     # drop k=0 mode and cut at kmax (smallest Nyquist)