diff --git a/flox/visualize.py b/flox/visualize.py
index c3cd6c816..bdf33b4fe 100644
--- a/flox/visualize.py
+++ b/flox/visualize.py
@@ -82,6 +82,7 @@ def visualize_groups_1d(array, labels, axis=-1, colors=None, cmap=None):
     assert labels.ndim == 1
     factorized, unique_labels = pd.factorize(labels)
     assert np.array(labels).ndim == 1
+    assert len(labels) == array.shape[axis]
     chunks = array.chunks[axis]
 
     if colors is None:
@@ -96,7 +97,7 @@ def visualize_groups_1d(array, labels, axis=-1, colors=None, cmap=None):
     plt.figure()
     i0 = 0
     for i in chunks:
-        lab = labels[i0 : i0 + i]
+        lab = factorized[i0 : i0 + i]
         col = [colors[label] for label in lab] + [(1, 1, 1)]
         draw_mesh(
             1,
@@ -170,3 +171,22 @@ def visualize_cohorts_2d(by, array, method="cohorts"):
     ax[1].set_title(f"{len(before_merged)} cohorts")
     ax[2].set_title(f"{len(merged)} merged cohorts")
     f.set_size_inches((6, 6))
+
+
+def visualize_groups_1d_long(array, labels, axis):
+    labels = np.asarray(labels)
+    assert labels.ndim == 1
+    factorized, unique_labels = pd.factorize(labels)
+    assert np.array(labels).ndim == 1
+    assert len(labels) == array.shape[axis]
+    chunks = array.chunks[axis]
+
+    idx = np.concatenate([np.concatenate([np.ones((c,)), np.array([np.nan])]) for c in chunks])[:-1]
+    labels_ = labels[np.nancumsum(idx).astype(int) - 1].astype(float)
+    labels_[np.isnan(idx)] = np.nan
+    ncol = 5 * (20 + 1)
+    extra = ncol - len(idx) % ncol
+    idx2d = np.pad(labels_, (0, extra), constant_values=np.nan).reshape(-1, ncol)
+
+    plt.figure()
+    plt.pcolormesh(idx2d, cmap=mpl.cm.Reds)