fix: natural_sort_key improper sorting of some integers

`natural_sort_key` improperly treating some integers as dates, leading to incorrect sorting of numbers.

`natural_sort_key` no longer sorts strings that are integer style dates, e.g. `"20251030"` use `date_sort_key` for those.

Author: ragardner

docs/CHANGELOG.md

@@ -1,6 +1,13 @@
 ### Version 7.6.0
+#### Fixed:
+- `natural_sort_key` improperly treating some integers as dates, leading to incorrect sorting of numbers.
+
 #### Changed:
 - Copying cells to clipboard which are `None` now copies an empty string `""`, previously copied `"None"` to clipboard.
+- `natural_sort_key` no longer sorts strings that are integer style dates, e.g. `"20251030"` use `date_sort_key` for those.
+
+#### Added:
+- `date_sort_key` to emulate previous behavior of `natural_sort_key` where for strings, a date conversion is attempted before a float and integer style dates are handled. This may cause errors in some edge cases though [#316](https://github.com/ragardner/tksheet/issues/316).
 
 ### Version 7.5.19
 #### Addressed:

docs/DOCUMENTATION.html

@@ -408,6 +408,7 @@
 <li><a href="#natural_sort_key">natural_sort_key</a></li>
 <li><a href="#version_sort_key">version_sort_key</a></li>
 <li><a href="#fast_sort_key">fast_sort_key</a></li>
+<li><a href="#date_sort_key">date_sort_key</a></li>
 <li><a href="#setting-the-default-sorting-key">Setting the default sorting key</a></li>
 <li><a href="#sorting-cells">Sorting cells</a></li>
 <li><a href="#sorting-row-values">Sorting row values</a></li>
@@ -4365,6 +4366,7 @@ <h4 id="natural_sort_key"><strong>natural_sort_key</strong></h4>
 <ul>
 <li>Won't sort string version numbers.</li>
 <li>Will convert strings to floats.</li>
+<li>Will try to convert strings to floats before it tries to convert them to dates.</li>
 <li>Will sort strings that are file paths.</li>
 </ul>
 <p>Order:</p>
@@ -4414,6 +4416,28 @@ <h4 id="fast_sort_key"><strong>fast_sort_key</strong></h4>
 <li>strings (including paths as POSIX strings) &amp; unknown objects with <strong>str</strong></li>
 <li>unknown objects</li>
 </ul>
+<h4 id="date_sort_key"><strong>date_sort_key</strong></h4>
+<p>A key for sorting with an emphasis on dates over numbers. This used to be <code>natural_sort_key</code> in tksheet versions prior to <code>7.6.0</code>.</p>
+<ul>
+<li>Won't sort string version numbers</li>
+<li>Will try to convert strings to dates before it tries floats<ul>
+<li>This may result in errors in integer date edge cases</li>
+</ul>
+</li>
+<li>Will convert strings to floats</li>
+<li>
+<p>Will sort strings that are file paths</p>
+</li>
+<li>
+<p>None</p>
+</li>
+<li>Empty strings</li>
+<li>bool</li>
+<li>int, float (inc. strings that are numbers)</li>
+<li>datetime (inc. strings that are dates)</li>
+<li>strings (including string file paths and paths as POSIX strings) &amp; unknown objects with <strong>str</strong></li>
+<li>unknown objects</li>
+</ul>
 <h4 id="setting-the-default-sorting-key"><strong>Setting the default sorting key</strong></h4>
 <p>Setting the sorting key at initialization:</p>
 <pre><code class="language-python">from tksheet import Sheet, natural_sort_key

docs/DOCUMENTATION.md

@@ -3976,6 +3976,7 @@ This is the **default** sorting key for natural sorting of various Python types:
 
 - Won't sort string version numbers.
 - Will convert strings to floats.
+- Will try to convert strings to floats before it tries to convert them to dates.
 - Will sort strings that are file paths.
 
 Order:
@@ -4021,6 +4022,24 @@ A faster key for natural sorting of various Python types. This key should probab
 5. strings (including paths as POSIX strings) & unknown objects with __str__
 6. unknown objects
 
+#### **date_sort_key**
+
+A key for sorting with an emphasis on dates over numbers. This used to be `natural_sort_key` in tksheet versions prior to `7.6.0`.
+
+- Won't sort string version numbers
+- Will try to convert strings to dates before it tries floats
+    - This may result in errors in integer date edge cases
+- Will convert strings to floats
+- Will sort strings that are file paths
+
+0. None
+1. Empty strings
+2. bool
+3. int, float (inc. strings that are numbers)
+4. datetime (inc. strings that are dates)
+5. strings (including string file paths and paths as POSIX strings) & unknown objects with __str__
+6. unknown objects
+
 #### **Setting the default sorting key**
 
 Setting the sorting key at initialization:

tksheet/sorting.py

@@ -151,6 +151,85 @@ def natural_sort_key(item: Any) -> tuple[int, ...]:
     - Will convert strings to floats
     - Will sort strings that are file paths
 
+    0. None
+    1. Empty strings
+    2. bool
+    3. int, float (inc. strings that are numbers)
+    4. datetime (inc. strings that are dates, except for pure integer dates)
+    5. strings (including string file paths and paths as POSIX strings) & unknown objects with __str__
+    6. unknown objects
+    """
+    if isinstance(item, str):
+        if item:
+            try:
+                return (3, float(item))
+            except ValueError:
+                for date_format in date_formats:
+                    try:
+                        return (4, datetime.strptime(item, date_format).timestamp())
+                    except ValueError:
+                        continue
+            # the same as _string_fallback
+            components = split(r"[/\\]", item)
+            if components[-1]:
+                return (
+                    5,
+                    len(components),
+                    tuple(
+                        int(e) if e.isdigit() else e.lower()
+                        for comp in components[:-1]
+                        for e in split(r"(\d+)", comp)
+                        if e
+                    ),
+                    tuple(int(e) if e.isdigit() else e.lower() for e in split(r"(\d+)", components[-1])),
+                )
+            else:
+                return (
+                    5,
+                    len(components),
+                    tuple(
+                        int(e) if e.isdigit() else e.lower()
+                        for comp in components[:-1]
+                        for e in split(r"(\d+)", comp)
+                        if e
+                    ),
+                    (),
+                )
+        else:
+            return (1, item)
+
+    elif item is None:
+        return (0,)
+
+    elif isinstance(item, bool):
+        return (2, item)
+
+    elif isinstance(item, (int, float)):
+        return (3, item)
+
+    elif isinstance(item, datetime):
+        return (4, item.timestamp())
+
+    elif isinstance(item, Path):
+        return _string_fallback(item.as_posix())
+
+    else:
+        try:
+            return _string_fallback(f"{item}")
+        except Exception:
+            return (6, item)
+
+
+def date_sort_key(item: Any) -> tuple[int, ...]:
+    """
+    A key for sorting with an emphasis on dates over numbers.
+
+    - Won't sort string version numbers
+    - Will try to convert strings to dates before it tries floats
+        - This may result in errors in integer date edge cases
+    - Will convert strings to floats
+    - Will sort strings that are file paths
+
     0. None
     1. Empty strings
     2. bool
@@ -166,7 +245,6 @@ def natural_sort_key(item: Any) -> tuple[int, ...]:
                     return (4, datetime.strptime(item, date_format).timestamp())
                 except ValueError:
                     continue
-
             try:
                 return (3, float(item))
             except ValueError:
@@ -423,7 +501,7 @@ def sort_tree_rows_by_column(
         return [], {}
 
     if key is None:
-        key = natural_sort_key  # Assuming natural_sort_key is defined elsewhere
+        key = natural_sort_key
 
     # Define the sort_reverse parameter to avoid unnecessary reversals
     sort_reverse = not reverse