symlog transform of the target

sCOCA_ML/prepare_data/utils_functions.py

@@ -0,0 +1,41 @@
+import torch
+
+class Transformation:
+    def __init__(self, transform=None, inverse_transform=None):
+        self.transform = transform
+        self.inverse_transform = inverse_transform
+
+    def __call__(self, sample):
+        if self.transform:
+            return self.transform(sample)
+        return sample
+    
+    def inverse(self, sample):
+        if self.inverse_transform:
+            return self.inverse_transform(sample)
+        return sample
+    
+
+def custom_symlog(x, threshold=1.):
+    """
+    Custom symmetric logarithm function.
+    Returns log(1 + |x| / threshold) * sign(x) * threshold.
+    """
+    return torch.sign(x) * torch.log1p(torch.abs(x) / threshold) * threshold
+
+def custom_inverse_symlog(x, threshold=1.):
+    """
+    Custom inverse symmetric logarithm function.
+    Returns sign(x) * (exp(|x| / threshold) - 1) * threshold.
+    """
+    return torch.sign(x) * (torch.exp(torch.abs(x) / threshold) - 1) * threshold
+
+
+def CustomSymlogTransform(threshold=1.):
+    """
+    Custom transformation object for symmetric logarithm.
+    """
+    return Transformation(
+        transform=lambda x: custom_symlog(x, threshold),
+        inverse_transform=lambda x: custom_inverse_symlog(x, threshold)
+    )