From e5f76ff203a39c859561ba361fb72171f2acf935 Mon Sep 17 00:00:00 2001
From: ahmadtourei <ahmadtourei@gmail.com>
Date: Mon, 13 Jan 2025 12:49:37 -0700
Subject: [PATCH] fix_correlate_shift_coord_length

---
 dascore/proc/correlate.py          |  3 +++
 docs/recipes/how_to_contribute.qmd |  1 -
 tests/test_proc/test_correlate.py  | 28 ++++++++++++++++++++++++++++
 3 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/dascore/proc/correlate.py b/dascore/proc/correlate.py
index 7fafad06..bf80c0d6 100644
--- a/dascore/proc/correlate.py
+++ b/dascore/proc/correlate.py
@@ -73,6 +73,8 @@ def correlate_shift(patch, dim, undo_weighting=True):
     step = coord.step
     new_start = -np.ceil((len(coord) - 1) / 2) * step
     new_end = np.ceil((len(coord) - 1) / 2) * step
+    if len(coord) % 2 != 0:  # Odd coord length
+        new_end += step
     new_coord = dc.get_coord(start=new_start, stop=new_end, step=step)
     assert len(new_coord) == len(coord)
     cm = patch.coords
@@ -214,5 +216,6 @@ def correlate(
     # Undo fft if this function did one, shift, and update coord.
     if not input_dft:
         idft = out.idft.func(out)
+        # breakpoint()
         out = idft.correlate_shift.func(idft, fft_dim)
     return out
diff --git a/docs/recipes/how_to_contribute.qmd b/docs/recipes/how_to_contribute.qmd
index 87ed3ec3..5a13f438 100644
--- a/docs/recipes/how_to_contribute.qmd
+++ b/docs/recipes/how_to_contribute.qmd
@@ -29,7 +29,6 @@ pip install -e ".[dev]"
 ```
 
 ```bash
-cd dascore
 pytest
 ```
 
diff --git a/tests/test_proc/test_correlate.py b/tests/test_proc/test_correlate.py
index 8b559ecc..f32e5966 100644
--- a/tests/test_proc/test_correlate.py
+++ b/tests/test_proc/test_correlate.py
@@ -12,6 +12,18 @@
 class TestCorrelateShift:
     """Tests for the correlation shift function."""
 
+    @pytest.fixture(scope="class")
+    def random_patch_odd(self):
+        """Create a random patch with odd number of time samples."""
+        patch = dc.get_example_patch("random_das", shape=(2, 11))
+        return patch
+
+    @pytest.fixture(scope="class")
+    def random_patch_even(self):
+        """Create a random patch with even number of time samples."""
+        patch = dc.get_example_patch("random_das", shape=(2, 10))
+        return patch
+
     def test_auto_correlation(self, random_dft_patch):
         """Perform auto correlation and undo shifting."""
         dft_conj = random_dft_patch.conj()
@@ -26,6 +38,22 @@ def test_auto_correlation(self, random_dft_patch):
         argmax = np.argmax(random_dft_patch.data, axis=time_ax)
         assert np.all(coord_array[argmax] == dc.to_timedelta64(0))
 
+    def test_auto_correlation_odd_coord(self, random_patch_odd):
+        """Ensure correlate_shift works when dim's coord length is odd."""
+        dft = random_patch_odd.dft(dim="time")
+        dft_conj = dft.conj()
+        dft_sq = dft * dft_conj
+        idft = dft_sq.idft()
+        assert isinstance(idft.correlate_shift(dim="time"), dc.Patch)
+
+    def test_auto_correlation_even_coord(self, random_patch_even):
+        """Ensure correlate_shift works when dim's coord length is even."""
+        dft = random_patch_even.dft(dim="time")
+        dft_conj = dft.conj()
+        dft_sq = dft * dft_conj
+        idft = dft_sq.idft()
+        assert isinstance(idft.correlate_shift(dim="time"), dc.Patch)
+
 
 class TestCorrelateInternal:
     """Tests case of intra-patch correlation function."""