set std of non-finite subseq to np.nan to avoid divide by 0 warning

Author: NimaSarajpoor

stumpy/core.py

@@ -2254,7 +2254,7 @@ def preprocess_diagonal(
 
     M_T, Σ_T = compute_mean_std(T, m)
     Σ_T[T_subseq_isconstant] = 1.0  # Avoid divide by zero in next inversion step
-    Σ_T[~T_subseq_isfinite] = 1.0
+    Σ_T[~T_subseq_isfinite] = np.nan
     Σ_T_inverse = 1.0 / Σ_T
     M_T_m_1, _ = compute_mean_std(T, m - 1)
 

tests/test_core.py

@@ -885,7 +885,7 @@ def test_preprocess_diagonal():
 
     ref_T = np.array([0, 0, 2, 3, 4, 5, 6, 7, 0, 9], dtype=float)
     ref_M, ref_Σ = naive.compute_mean_std(ref_T, m)
-    ref_Σ[~T_subseq_isfinite] = 1.0
+    ref_Σ[~T_subseq_isfinite] = np.nan
     ref_Σ_inverse = 1.0 / ref_Σ
     ref_M_m_1, _ = naive.compute_mean_std(ref_T, m - 1)