Fix sequence_join treating any string with a space as a datetime

pygmt/helpers/utils.py

@@ -2,6 +2,7 @@
 Utilities and common tasks for wrapping the GMT modules.
 """
 
+import contextlib
 import io
 import os
 import shutil
@@ -920,14 +921,13 @@ def sequence_join(
         # or integer number for timedelta64.
         _values = []
         for item in value:
+            _value = str(item)
             if isinstance(item, np.timedelta64):  # Convert timedelta64 to numeric value
-                _values.append(str(item.astype(int)))
-            elif " " in str(item):
-                _values.append(
-                    np.datetime_as_string(np.asarray(item, dtype="datetime64"))  # type: ignore[arg-type]
-                )
-            else:
-                _values.append(str(item))
+                _value = str(item.astype(int))
+            elif " " in _value:  # Likely a datetime-like object.
+                with contextlib.suppress(ValueError):
+                    _value = np.datetime_as_string(np.asarray(item, dtype="datetime64"))  # type: ignore[assignment]
+            _values.append(_value)
         return sep.join(_values)  # type: ignore[arg-type]
 
     # Now it must be a 2-D sequence.

pygmt/tests/test_helpers.py

@@ -7,6 +7,7 @@
 from pathlib import Path
 from unittest.mock import patch
 
+import pandas as pd
 import pytest
 import xarray as xr
 from pygmt import Figure
@@ -17,6 +18,7 @@
     build_arg_list,
     kwargs_to_strings,
     launch_external_viewer,
+    sequence_join,
     unique_name,
 )
 from pygmt.helpers.testing import load_static_earth_relief, skip_if_no
@@ -151,6 +153,22 @@ def test_args_in_kwargs():
     assert not args_in_kwargs(args=failing_args, kwargs=kwargs)
 
 
+def test_sequence_join_strings_with_spaces():
+    """
+    Test that sequence_join handles strings with spaces and datetime-like objects.
+    Regression test for https://github.com/GenericMappingTools/pygmt/issues/4960.
+    """
+    assert sequence_join(["W", "E", "S", "North Pole"], sep=",", size=4) == (
+        "W,E,S,North Pole"
+    )
+    assert sequence_join(["2010-01-01 12:00:00", "2010-01-02"], sep="/") == (
+        "2010-01-01T12:00:00/2010-01-02"
+    )
+    assert sequence_join([pd.Timestamp("2010-01-01 12:00:00"), 1], sep="/") == (
+        "2010-01-01T12:00:00.000000/1"
+    )
+
+
 def test_skip_if_no():
     """
     Test that the skip_if_no helper testing function returns a pytest.mask.skipif mark