feat: adding greedy algorithm for pauli grouping

Author: hJaffaliColibritd

mpqp/core/instruction/measurement/expectation_value.py

@@ -371,7 +371,10 @@ def _check_targets_order(self):
         )
 
     def get_pauli_grouping(
-        self, method: Literal["full_commutative_graph", "b"] = "full_commutative_graph"
+        self,
+        method: Literal[
+            "full_clique", "full_greedy", "qubit_wise_clique"
+        ] = "full_greedy",
     ) -> list[set[PauliStringMonomial]]:
         """
         TODO: decompose the observables, regroup the pauli measurements by commutativity relation,

mpqp/tools/pauli_grouping.py

@@ -1,7 +1,32 @@
 from mpqp.core.instruction.measurement.pauli_string import PauliStringMonomial
 
 
-def full_commutation_pauli_grouping(monomials: set[PauliStringMonomial]):
+def full_commutation_pauli_grouping_greedy(monomials: set[PauliStringMonomial]):
+    """
+    TODO: comment
+    Args:
+        monomials:
+
+    Returns:
+
+    """
+    groups = []
+
+    for m in monomials:
+        added = False
+        for group in groups:
+            if all(m.commutes_with(m_g) for m_g in group):
+                group.append(m)
+                added = True
+                break
+
+        if not added:
+            groups.append([m])
+
+    return groups
+
+
+def full_commutation_pauli_grouping_ibm_clique(monomials: set[PauliStringMonomial]):
     pass