add find_common_edge_idx

Author: Yoshinori Sueno

sotodlib/core/flagman.py

@@ -354,3 +354,23 @@ def sparse_to_ranges_matrix(arr, buffer=0, close_gaps=0, val=True):
         x[i].close_gaps(close_gaps)
     return x
 
+def find_common_edge_idx(flags):
+    """Find the common valid range across multiple RangesMatrix objects.
+
+    Args:
+        flags (RangesMatrix): An instance of so3g.proj.RangesMatrix indicating flagged time ranges.
+    Returns:
+        min_idx, max_idx: minmum and maximum indices that has False flag across all detectros.
+    """
+    max_val = max(arr.complement().ranges()[:, 1].max() for arr in flags)
+    common_mask = np.ones(max_val, dtype=bool)
+    for arr in flags:
+        mask = np.zeros(max_val, dtype=bool)
+        for start, end in arr.complement().ranges():
+            mask[start:end] = True
+        common_mask &= mask
+
+    valid_indices = np.where(common_mask)[0]
+    if len(valid_indices) == 0:
+        raise ValueError("No common valid range found across all flags.")
+    return valid_indices[0], valid_indices[-1]

sotodlib/preprocess/processes.py

@@ -2066,13 +2066,14 @@ class TrimFlagEdge(_Preprocess):
         - name: "trim_flag_edge"
           process:
             flags: "pca_exclude"
+    
+    .. autofunction:: sotodlib.core.flagman.find_common_edge_idx
     """
     name = 'trim_flag_edge'
 
     def process(self, aman, proc_aman, sim=False):
         flags = aman.flags.get(self.process_cfgs.get('flags'))
-        trimst = np.where(~np.any(flags.mask(), axis = 0))[0][0]
-        trimen = np.where(~np.any(flags.mask(), axis = 0))[0][-1]
+        trimst, trimen = core.flagman.find_common_edge_idx(flags)
         aman.restrict('samps', (aman.samps.offset + trimst,
                                 aman.samps.offset + trimen))
         proc_aman.restrict('samps', (proc_aman.samps.offset + trimst,