Improve the readability of Tableau str.

Author: babacry

cirq-core/cirq/qis/clifford_tableau.py

@@ -326,31 +326,35 @@ def __str__(self) -> str:
         return string
 
     def _str_full_(self) -> str:
-        stable_col_width = max(7, self.n * 2 + 3)
-        destable_col_width = max(10, self.n * 2 + 4)
+        left_col_width = max(7, self.n * 2 + 3)
+        right_col_width = max(10, self.n * 2 + 4)
 
-        def fill_row(left: str, right: str, mid='|', fillchar=' ') -> str:
-            row_str = left.ljust(stable_col_width, fillchar) + mid + right.ljust(destable_col_width, fillchar)
-            return row_str
+        def fill_row(left: str, right: str, mid='|', fill=' ') -> str:
+            return left.ljust(left_col_width, fill) + mid + right.ljust(right_col_width, fill)
 
-        def pauli_from_matrix(r: int, c: int):
+        def pauli_from_matrix(r: int, c: int) -> str:
             return {
                 (True, False): f'X{c}',
                 (False, True): f'Z{c}',
                 (True, True): f'Y{c}',
                 (False, False): '  ',
             }[(self.xs[r, c], self.zs[r, c])]
-        
-        title_row = fill_row("stable", " destable")
-        divider = fill_row("", "", mid="+", fillchar='-')
+
+        title_row = fill_row('stable', ' destable')
+        divider = fill_row('', '', mid='+', fill='-')
         contents = [
-            fill_row(left = "{sign} {paulis}".format( # from row i+n
-                sign='-' if self.rs[i + self.n] else '+',
-                paulis=''.join([pauli_from_matrix(i+self.n, j) for j in range(self.n)])),
-            right = " {sign} {paulis}".format( # from row i
-                sign='-' if self.rs[i] else '+',
-                paulis=''.join([pauli_from_matrix(i, j) for j in range(self.n)])))
-        for i in range(self.n)]
+            fill_row(
+                left='{sign} {paulis}'.format(  # from row i+n
+                    sign='-' if self.rs[i + self.n] else '+',
+                    paulis=''.join([pauli_from_matrix(i + self.n, j) for j in range(self.n)]),
+                ),
+                right=' {sign} {paulis}'.format(  # from row i
+                    sign='-' if self.rs[i] else '+',
+                    paulis=''.join([pauli_from_matrix(i, j) for j in range(self.n)]),
+                ),
+            )
+            for i in range(self.n)
+        ]
 
         return '\n'.join([title_row, divider, *contents])
 

cirq-core/cirq/qis/clifford_tableau_test.py

@@ -291,6 +291,7 @@ def test_repr():
 
 def test_str_full():
     import logging
+
     t = cirq.CliffordTableau(num_qubits=1)
     expected_str = r"""stable | destable 
 -------+----------