Backport PR #47121 on branch 1.4.x (BUG: read_excel loading some xlsx ints as floats) (#47271)

Backport PR #47121: BUG: read_excel loading some xlsx ints as floats

Co-authored-by: Andrew Hawyrluk <50434302+ahawryluk@users.noreply.github.com>

Author: simonjayhawkins

doc/source/whatsnew/v1.4.3.rst

@@ -24,6 +24,7 @@ Fixed regressions
 - Fixed regression in :func:`read_csv` with ``index_col=False`` identifying first row as index names when ``header=None`` (:issue:`46955`)
 - Fixed regression in :meth:`.DataFrameGroupBy.agg` when used with list-likes or dict-likes and ``axis=1`` that would give incorrect results; now raises ``NotImplementedError`` (:issue:`46995`)
 - Fixed regression in :meth:`DataFrame.resample` and :meth:`DataFrame.rolling` when used with list-likes or dict-likes and ``axis=1`` that would raise an unintuitive error message; now raises ``NotImplementedError`` (:issue:`46904`)
+- Fixed regression in :func:`read_excel` returning ints as floats on certain input sheets (:issue:`46988`)
 - Fixed regression in :meth:`DataFrame.shift` when ``axis`` is ``columns`` and ``fill_value`` is absent, ``freq`` is ignored (:issue:`47039`)
 
 .. ---------------------------------------------------------------------------

pandas/io/excel/_openpyxl.py

@@ -560,8 +560,14 @@ def _convert_cell(self, cell, convert_float: bool) -> Scalar:
             return ""  # compat with xlrd
         elif cell.data_type == TYPE_ERROR:
             return np.nan
-        elif not convert_float and cell.data_type == TYPE_NUMERIC:
-            return float(cell.value)
+        elif cell.data_type == TYPE_NUMERIC:
+            # GH5394, GH46988
+            if convert_float:
+                val = int(cell.value)
+                if val == cell.value:
+                    return val
+            else:
+                return float(cell.value)
 
         return cell.value
 

pandas/tests/io/data/excel/ints_spelled_with_decimals.xlsx

@@ -375,3 +375,11 @@ def test_read_empty_with_blank_row(datapath, ext, read_only):
         wb.close()
     expected = DataFrame()
     tm.assert_frame_equal(result, expected)
+
+
+def test_ints_spelled_with_decimals(datapath, ext):
+    # GH 46988 - openpyxl returns this sheet with floats
+    path = datapath("io", "data", "excel", f"ints_spelled_with_decimals{ext}")
+    result = pd.read_excel(path)
+    expected = DataFrame(range(2, 12), columns=[1])
+    tm.assert_frame_equal(result, expected)