From d4b610753791d6c6bfbc3ba1dec69f8d473e7786 Mon Sep 17 00:00:00 2001
From: "Kevin J. Sung" <kevjsung@umich.edu>
Date: Fri, 20 Sep 2024 09:49:39 -0500
Subject: [PATCH 1/4] add tests that shows config recovery fails at 74 bits

---
 test/test_configuration_recovery.py | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/test/test_configuration_recovery.py b/test/test_configuration_recovery.py
index 02dfb3b..218cd38 100644
--- a/test/test_configuration_recovery.py
+++ b/test/test_configuration_recovery.py
@@ -93,6 +93,21 @@ def test_recover_configurations(self):
             )
             self.assertTrue((expected_mat == mat_rec).all())
             self.assertTrue((expected_probs == probs_rec).all())
+        with self.subTest("Test with more than 73 bits. Ones to zeros."):
+            n_bits = 74
+            rng = np.random.default_rng(554)
+            bs_mat = rng.integers(2, size=(1, n_bits), dtype=bool)
+            probs = np.array([1.0])
+            occs = np.zeros(n_bits)
+            num_a = 0
+            num_b = 0
+            expected_mat = np.zeros((1, n_bits), dtype=bool)
+            expected_probs = np.array([1.0])
+            mat_rec, probs_rec = recover_configurations(
+                bs_mat, probs, occs, num_a, num_b, rand_seed=4224
+            )
+            self.assertTrue((expected_mat == mat_rec).all())
+            self.assertTrue((expected_probs == probs_rec).all())
         with self.subTest("Bad hamming."):
             bs_mat = np.array([[True, True, True, True]])
             probs = np.array([1.0])

From 89e6259bb1c2ca4cd8a27aa1180088271627957b Mon Sep 17 00:00:00 2001
From: "Kevin J. Sung" <kevjsung@umich.edu>
Date: Thu, 19 Sep 2024 21:10:55 -0500
Subject: [PATCH 2/4] don't use array2string

---
 qiskit_addon_sqd/configuration_recovery.py | 2 +-
 qiskit_addon_sqd/counts.py                 | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/qiskit_addon_sqd/configuration_recovery.py b/qiskit_addon_sqd/configuration_recovery.py
index 8b8c6a2..e09d24e 100644
--- a/qiskit_addon_sqd/configuration_recovery.py
+++ b/qiskit_addon_sqd/configuration_recovery.py
@@ -115,7 +115,7 @@ def recover_configurations(
             num_elec_b,
             rand_seed=rand_seed,
         )
-        bs_str = np.array2string(bs_corrected.astype(int), separator="")[1:-1]
+        bs_str = "".join("1" if bit else "0" for bit in bs_corrected)
         corrected_dict[bs_str] = corrected_dict.get(bs_str, 0.0) + freq
     bs_mat_out = np.array([[bit == "1" for bit in bs] for bs in corrected_dict])
     freqs_out = np.array([f for f in corrected_dict.values()])
diff --git a/qiskit_addon_sqd/counts.py b/qiskit_addon_sqd/counts.py
index 85b871d..01bd3fa 100644
--- a/qiskit_addon_sqd/counts.py
+++ b/qiskit_addon_sqd/counts.py
@@ -82,7 +82,7 @@ def generate_counts_uniform(
     bts_matrix = np.random.choice([0, 1], size=(num_samples, num_bits))
     for i in range(num_samples):
         bts_arr = bts_matrix[i, :].astype("int")
-        bts = np.array2string(bts_arr, separator="")[1:-1]
+        bts = "".join("1" if bit else "0" for bit in bts_arr)
         sample_dict[bts] = sample_dict.get(bts, 0) + 1
 
     return sample_dict
@@ -142,7 +142,7 @@ def generate_counts_bipartite_hamming(
         bts_arr[dn_flips] = 1
         bts_arr[up_flips + num_bits // 2] = 1
         bts_arr = bts_arr.astype("int")
-        bts = np.array2string(bts_arr, separator="")[1:-1]
+        bts = "".join("1" if bit else "0" for bit in bts_arr)
 
         # Add the bitstring to the sample dict
         sample_dict[bts] = sample_dict.get(bts, 0) + 1

From fc0c21939c4385bc17e2c9e5720034aaf1e49263 Mon Sep 17 00:00:00 2001
From: "Kevin J. Sung" <kevjsung@umich.edu>
Date: Fri, 20 Sep 2024 09:51:27 -0500
Subject: [PATCH 3/4] actually 72 is the largest even number

---
 test/test_configuration_recovery.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/test_configuration_recovery.py b/test/test_configuration_recovery.py
index 218cd38..cb43e6a 100644
--- a/test/test_configuration_recovery.py
+++ b/test/test_configuration_recovery.py
@@ -93,7 +93,7 @@ def test_recover_configurations(self):
             )
             self.assertTrue((expected_mat == mat_rec).all())
             self.assertTrue((expected_probs == probs_rec).all())
-        with self.subTest("Test with more than 73 bits. Ones to zeros."):
+        with self.subTest("Test with more than 72 bits. Ones to zeros."):
             n_bits = 74
             rng = np.random.default_rng(554)
             bs_mat = rng.integers(2, size=(1, n_bits), dtype=bool)

From 75d8ba224a98c00ab4f4ba1287850adab604a1d8 Mon Sep 17 00:00:00 2001
From: "Kevin J. Sung" <kevjsung@umich.edu>
Date: Fri, 20 Sep 2024 11:20:48 -0500
Subject: [PATCH 4/4] add release note

---
 releasenotes/notes/no-array2string-efb9b050ca6efc29.yaml | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 releasenotes/notes/no-array2string-efb9b050ca6efc29.yaml

diff --git a/releasenotes/notes/no-array2string-efb9b050ca6efc29.yaml b/releasenotes/notes/no-array2string-efb9b050ca6efc29.yaml
new file mode 100644
index 0000000..80f6fef
--- /dev/null
+++ b/releasenotes/notes/no-array2string-efb9b050ca6efc29.yaml
@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    Fixes a bug that caused configuration recovery to fail on bitstrings of length greater than 72.