From 05503fa5f7413a25873938d5d3620d7585c32950 Mon Sep 17 00:00:00 2001
From: Alex Nordin <anordin@mit.edu>
Date: Sat, 13 Apr 2019 23:16:05 -0500
Subject: [PATCH 01/15] BUG resolving issue 26051 and adding a unit test.

---
 pandas/core/generic.py               |  8 ++++++++
 pandas/tests/generic/test_generic.py | 11 +++++++++++
 2 files changed, 19 insertions(+)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 885c499c58dfa..dcbcb258af25f 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -2146,8 +2146,16 @@ def to_excel(self, excel_writer, sheet_name="Sheet1", na_rep="",
                  index_label=None, startrow=0, startcol=0, engine=None,
                  merge_cells=True, encoding=None, inf_rep="inf", verbose=True,
                  freeze_panes=None):
+
         df = self if isinstance(self, ABCDataFrame) else self.to_frame()
 
+        max_rows = 2**20
+        max_cols = 2**14
+        num_rows, num_cols = df.shape
+        if num_rows > max_rows or num_cols > max_cols:
+            raise ValueError(f"This sheet is too large! Your sheet size is: {(num_rows, num_cols)}. "
+                    f"Max sheet size is: {(max_rows, max_cols)}.")
+
         from pandas.io.formats.excel import ExcelFormatter
         formatter = ExcelFormatter(df, na_rep=na_rep, cols=columns,
                                    header=header,
diff --git a/pandas/tests/generic/test_generic.py b/pandas/tests/generic/test_generic.py
index d3b63e428b374..462a7fb90b22e 100644
--- a/pandas/tests/generic/test_generic.py
+++ b/pandas/tests/generic/test_generic.py
@@ -569,6 +569,7 @@ def test_copy_and_deepcopy(self):
         (-1, "bfill", None, [0, 0, -.5, -.5, -.6, np.nan, np.nan, np.nan]),
         (-1, "bfill", 1, [np.nan, 0, -.5, -.5, -.6, np.nan, np.nan, np.nan])
     ])
+
     def test_pct_change(self, periods, fill_method, limit, exp):
         vals = [np.nan, np.nan, 1, 2, 4, 10, np.nan, np.nan]
         obj = self._typ(vals)
@@ -583,6 +584,16 @@ def test_pct_change(self, periods, fill_method, limit, exp):
 class TestNDFrame(object):
     # tests that don't fit elsewhere
 
+    def test_to_excel_size(self):
+        BREAKING_SHAPE = (2**20 + 1, 2**14 + 1)
+        arr = np.zeros(shape=BREAKING_SHAPE)
+        df = pd.DataFrame(arr)
+        filepath = 'test.xlsx'
+
+        with pytest.raises(ValueError) as error_info:
+            df.to_excel(filepath)
+
+
     def test_sample(sel):
         # Fixes issue: 2419
         # additional specific object based tests

From c5f9db90d99fb845981d3691269dc18d863e06ea Mon Sep 17 00:00:00 2001
From: Alex Nordin <anordin@mit.edu>
Date: Sat, 13 Apr 2019 23:36:14 -0500
Subject: [PATCH 02/15] CLN. Cleaning up PEP-8 errors.

---
 pandas/core/generic.py               | 5 +++--
 pandas/tests/generic/test_generic.py | 4 +---
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index dcbcb258af25f..44c59aaa7a37d 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -2153,8 +2153,9 @@ def to_excel(self, excel_writer, sheet_name="Sheet1", na_rep="",
         max_cols = 2**14
         num_rows, num_cols = df.shape
         if num_rows > max_rows or num_cols > max_cols:
-            raise ValueError(f"This sheet is too large! Your sheet size is: {(num_rows, num_cols)}. "
-                    f"Max sheet size is: {(max_rows, max_cols)}.")
+            raise ValueError(f"This sheet is too large! Your sheet size is: "
+                             f"{(num_rows, num_cols)}. "
+                             f"Max sheet size is: {(max_rows, max_cols)}.")
 
         from pandas.io.formats.excel import ExcelFormatter
         formatter = ExcelFormatter(df, na_rep=na_rep, cols=columns,
diff --git a/pandas/tests/generic/test_generic.py b/pandas/tests/generic/test_generic.py
index 462a7fb90b22e..9cb9ee26c1ae2 100644
--- a/pandas/tests/generic/test_generic.py
+++ b/pandas/tests/generic/test_generic.py
@@ -569,7 +569,6 @@ def test_copy_and_deepcopy(self):
         (-1, "bfill", None, [0, 0, -.5, -.5, -.6, np.nan, np.nan, np.nan]),
         (-1, "bfill", 1, [np.nan, 0, -.5, -.5, -.6, np.nan, np.nan, np.nan])
     ])
-
     def test_pct_change(self, periods, fill_method, limit, exp):
         vals = [np.nan, np.nan, 1, 2, 4, 10, np.nan, np.nan]
         obj = self._typ(vals)
@@ -590,10 +589,9 @@ def test_to_excel_size(self):
         df = pd.DataFrame(arr)
         filepath = 'test.xlsx'
 
-        with pytest.raises(ValueError) as error_info:
+        with pytest.raises(ValueError):
             df.to_excel(filepath)
 
-
     def test_sample(sel):
         # Fixes issue: 2419
         # additional specific object based tests

From f6abceb4754c22705658b314e04bfc8f9f55d4f3 Mon Sep 17 00:00:00 2001
From: Alex Nordin <anordin@mit.edu>
Date: Thu, 25 Apr 2019 22:42:07 -0400
Subject: [PATCH 03/15] Stylistic changes.

---
 pandas/core/generic.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 44c59aaa7a37d..ed079226cca9b 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -2149,13 +2149,13 @@ def to_excel(self, excel_writer, sheet_name="Sheet1", na_rep="",
 
         df = self if isinstance(self, ABCDataFrame) else self.to_frame()
 
-        max_rows = 2**20
-        max_cols = 2**14
+        excel_max_rows = 2**20
+        excel_max_cols = 2**14
         num_rows, num_cols = df.shape
-        if num_rows > max_rows or num_cols > max_cols:
+        if num_rows > excel_max_rows or num_cols > excel_max_cols:
             raise ValueError(f"This sheet is too large! Your sheet size is: "
                              f"{(num_rows, num_cols)}. "
-                             f"Max sheet size is: {(max_rows, max_cols)}.")
+                             f"Max sheet size is: {(excel_max_rows, excel_max_cols)}.")
 
         from pandas.io.formats.excel import ExcelFormatter
         formatter = ExcelFormatter(df, na_rep=na_rep, cols=columns,

From 65fe420c265d61eea20f15fa6b6cfbc059fb2f14 Mon Sep 17 00:00:00 2001
From: Alex Nordin <anordin@mit.edu>
Date: Thu, 25 Apr 2019 23:03:06 -0400
Subject: [PATCH 04/15] Remove f strings due to python3.5 incompatibility.

---
 pandas/core/generic.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index ed079226cca9b..3030b29dab258 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -2153,9 +2153,9 @@ def to_excel(self, excel_writer, sheet_name="Sheet1", na_rep="",
         excel_max_cols = 2**14
         num_rows, num_cols = df.shape
         if num_rows > excel_max_rows or num_cols > excel_max_cols:
-            raise ValueError(f"This sheet is too large! Your sheet size is: "
-                             f"{(num_rows, num_cols)}. "
-                             f"Max sheet size is: {(excel_max_rows, excel_max_cols)}.")
+            raise ValueError("This sheet is too large! Your sheet size is: " +
+                             "{}, {} ".format(num_rows, num_cols) +
+                             "Max sheet size is: {}, {}".format(excel_max_rows, excel_max_cols))
 
         from pandas.io.formats.excel import ExcelFormatter
         formatter = ExcelFormatter(df, na_rep=na_rep, cols=columns,

From e0a9b7ef85faf69b0a4e6c2f1223e20d06c1d8f1 Mon Sep 17 00:00:00 2001
From: Alex Nordin <anordin@mit.edu>
Date: Tue, 30 Apr 2019 18:40:28 -0400
Subject: [PATCH 05/15] Moved code to excel.py and test_excel.py. Pytests
 failing due to xlrd deprecation error.

---
 pandas/core/generic.py               |  8 --------
 pandas/io/formats/excel.py           |  9 +++++++++
 pandas/tests/generic/test_generic.py |  9 ---------
 pandas/tests/io/test_excel.py        | 11 +++++++++++
 4 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 3030b29dab258..56fc8fc49110b 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -2149,14 +2149,6 @@ def to_excel(self, excel_writer, sheet_name="Sheet1", na_rep="",
 
         df = self if isinstance(self, ABCDataFrame) else self.to_frame()
 
-        excel_max_rows = 2**20
-        excel_max_cols = 2**14
-        num_rows, num_cols = df.shape
-        if num_rows > excel_max_rows or num_cols > excel_max_cols:
-            raise ValueError("This sheet is too large! Your sheet size is: " +
-                             "{}, {} ".format(num_rows, num_cols) +
-                             "Max sheet size is: {}, {}".format(excel_max_rows, excel_max_cols))
-
         from pandas.io.formats.excel import ExcelFormatter
         formatter = ExcelFormatter(df, na_rep=na_rep, cols=columns,
                                    header=header,
diff --git a/pandas/io/formats/excel.py b/pandas/io/formats/excel.py
index aa88f6c520c0d..cc165d2955dd0 100644
--- a/pandas/io/formats/excel.py
+++ b/pandas/io/formats/excel.py
@@ -341,6 +341,9 @@ class ExcelFormatter(object):
         This is only called for body cells.
     """
 
+    max_rows = 2**20
+    max_cols = 2**14
+            
     def __init__(self, df, na_rep='', float_format=None, cols=None,
                  header=True, index=True, index_label=None, merge_cells=False,
                  inf_rep='inf', style_converter=None):
@@ -647,6 +650,12 @@ def write(self, writer, sheet_name='Sheet1', startrow=0,
         """
         from pandas.io.excel import ExcelWriter
         from pandas.io.common import _stringify_path
+        
+        num_rows, num_cols = df.shape
+        if num_rows > self.max_rows or num_cols > self.max_cols:
+            raise ValueError("This sheet is too large! Your sheet size is: " +
+                             "{}, {} ".format(num_rows, num_cols) +
+                             "Max sheet size is: {}, {}".format(excel_max_rows, excel_max_cols))
 
         if isinstance(writer, ExcelWriter):
             need_save = False
diff --git a/pandas/tests/generic/test_generic.py b/pandas/tests/generic/test_generic.py
index 9cb9ee26c1ae2..d3b63e428b374 100644
--- a/pandas/tests/generic/test_generic.py
+++ b/pandas/tests/generic/test_generic.py
@@ -583,15 +583,6 @@ def test_pct_change(self, periods, fill_method, limit, exp):
 class TestNDFrame(object):
     # tests that don't fit elsewhere
 
-    def test_to_excel_size(self):
-        BREAKING_SHAPE = (2**20 + 1, 2**14 + 1)
-        arr = np.zeros(shape=BREAKING_SHAPE)
-        df = pd.DataFrame(arr)
-        filepath = 'test.xlsx'
-
-        with pytest.raises(ValueError):
-            df.to_excel(filepath)
-
     def test_sample(sel):
         # Fixes issue: 2419
         # additional specific object based tests
diff --git a/pandas/tests/io/test_excel.py b/pandas/tests/io/test_excel.py
index 1377888a58d07..553623f04278f 100644
--- a/pandas/tests/io/test_excel.py
+++ b/pandas/tests/io/test_excel.py
@@ -1212,6 +1212,17 @@ class and any subclasses, on account of the `autouse=True`
 class TestExcelWriter(_WriterBase):
     # Base class for test cases to run with different Excel writers.
 
+    # def test_excel_sheet_size(self):
+    #     assert False
+        
+    #     BREAKING_SHAPE = (2**20 + 1, 2**14 + 1)
+    #     arr = np.zeros(shape=BREAKING_SHAPE)
+    #     df = pd.DataFrame(arr)
+    #     filepath = 'test.xlsx'
+
+    #     with pytest.raises(ValueError):
+    #         df.to_excel(filepath)
+
     def test_excel_sheet_by_name_raise(self, *_):
         import xlrd
 

From 10ca447f8472064f2f23950761f3c574700a5f0a Mon Sep 17 00:00:00 2001
From: Alex Nordin <anordin@mit.edu>
Date: Thu, 2 May 2019 14:41:39 -0400
Subject: [PATCH 06/15] df -> self.df. new error: Pending Deprecation Warning

---
 pandas/io/formats/excel.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/io/formats/excel.py b/pandas/io/formats/excel.py
index cc165d2955dd0..6212b97660fb8 100644
--- a/pandas/io/formats/excel.py
+++ b/pandas/io/formats/excel.py
@@ -651,7 +651,7 @@ def write(self, writer, sheet_name='Sheet1', startrow=0,
         from pandas.io.excel import ExcelWriter
         from pandas.io.common import _stringify_path
         
-        num_rows, num_cols = df.shape
+        num_rows, num_cols = self.df.shape
         if num_rows > self.max_rows or num_cols > self.max_cols:
             raise ValueError("This sheet is too large! Your sheet size is: " +
                              "{}, {} ".format(num_rows, num_cols) +

From ed5d3b357ef532f2e2cd15e156c894145c407ef8 Mon Sep 17 00:00:00 2001
From: Alex Nordin <anordin@mit.edu>
Date: Mon, 13 May 2019 14:19:41 -0400
Subject: [PATCH 07/15] Addressed comments + ensured lint success.

---
 pandas/core/generic.py        |  1 -
 pandas/tests/io/test_excel.py | 18 ++++++++----------
 2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 56fc8fc49110b..885c499c58dfa 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -2146,7 +2146,6 @@ def to_excel(self, excel_writer, sheet_name="Sheet1", na_rep="",
                  index_label=None, startrow=0, startcol=0, engine=None,
                  merge_cells=True, encoding=None, inf_rep="inf", verbose=True,
                  freeze_panes=None):
-
         df = self if isinstance(self, ABCDataFrame) else self.to_frame()
 
         from pandas.io.formats.excel import ExcelFormatter
diff --git a/pandas/tests/io/test_excel.py b/pandas/tests/io/test_excel.py
index 553623f04278f..7deaf449b36bb 100644
--- a/pandas/tests/io/test_excel.py
+++ b/pandas/tests/io/test_excel.py
@@ -1212,16 +1212,14 @@ class and any subclasses, on account of the `autouse=True`
 class TestExcelWriter(_WriterBase):
     # Base class for test cases to run with different Excel writers.
 
-    # def test_excel_sheet_size(self):
-    #     assert False
-        
-    #     BREAKING_SHAPE = (2**20 + 1, 2**14 + 1)
-    #     arr = np.zeros(shape=BREAKING_SHAPE)
-    #     df = pd.DataFrame(arr)
-    #     filepath = 'test.xlsx'
-
-    #     with pytest.raises(ValueError):
-    #         df.to_excel(filepath)
+    def test_excel_sheet_size(self):        
+        breaking_shape = (2**20 + 1, 2**14 + 1)
+        arr = np.zeros(shape=breaking_shape)
+        df = pd.DataFrame(arr)
+
+        msg = "sheet is too large"
+        with pytest.raises(ValueError, match=msg):
+            df.to_excel(self.path)
 
     def test_excel_sheet_by_name_raise(self, *_):
         import xlrd

From dedf5dbaa046d429687fa421f51c15fce66fa61b Mon Sep 17 00:00:00 2001
From: Alex Nordin <anordin@mit.edu>
Date: Tue, 14 May 2019 14:31:59 -0400
Subject: [PATCH 08/15] re-structure test to decrease memory useage.

---
 pandas/tests/io/test_excel.py | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/pandas/tests/io/test_excel.py b/pandas/tests/io/test_excel.py
index 7deaf449b36bb..86ad8172a4878 100644
--- a/pandas/tests/io/test_excel.py
+++ b/pandas/tests/io/test_excel.py
@@ -1212,15 +1212,22 @@ class and any subclasses, on account of the `autouse=True`
 class TestExcelWriter(_WriterBase):
     # Base class for test cases to run with different Excel writers.
 
-    def test_excel_sheet_size(self):        
-        breaking_shape = (2**20 + 1, 2**14 + 1)
-        arr = np.zeros(shape=breaking_shape)
-        df = pd.DataFrame(arr)
+    def test_excel_sheet_size(self): 
+        breaking_row_count = 2**20 + 1
+        breaking_col_count = 2**14 + 1
+        #purposely using two arrays to prevent memory issues while testing
+        row_arr = np.zeros(shape=(breaking_row_count, 1))
+        col_arr = np.zeros(shape=(1, breaking_col_count))
+        row_df = pd.DataFrame(row_arr)
+        col_df = pd.DataFrame(col_arr)
 
         msg = "sheet is too large"
         with pytest.raises(ValueError, match=msg):
-            df.to_excel(self.path)
+            row_df.to_excel(self.path)
 
+        with pytest.raises(ValueError, match=msg):
+            col_df.to_excel(self.path)
+            
     def test_excel_sheet_by_name_raise(self, *_):
         import xlrd
 

From fde1703754be14531d335a91c98fe267c6af192f Mon Sep 17 00:00:00 2001
From: Alex Nordin <anordin@mit.edu>
Date: Tue, 14 May 2019 15:06:41 -0400
Subject: [PATCH 09/15] fix misnaming

---
 pandas/io/formats/excel.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/io/formats/excel.py b/pandas/io/formats/excel.py
index 6212b97660fb8..d467abcabfcf9 100644
--- a/pandas/io/formats/excel.py
+++ b/pandas/io/formats/excel.py
@@ -655,7 +655,7 @@ def write(self, writer, sheet_name='Sheet1', startrow=0,
         if num_rows > self.max_rows or num_cols > self.max_cols:
             raise ValueError("This sheet is too large! Your sheet size is: " +
                              "{}, {} ".format(num_rows, num_cols) +
-                             "Max sheet size is: {}, {}".format(excel_max_rows, excel_max_cols))
+                             "Max sheet size is: {}, {}".format(self.max_rows, self.max_cols))
 
         if isinstance(writer, ExcelWriter):
             need_save = False

From e035a2df24105a231202adf373ff4dddcd195fb1 Mon Sep 17 00:00:00 2001
From: Alex Nordin <alexander.f.nordin+git@gmail.com>
Date: Tue, 14 May 2019 19:02:31 -0400
Subject: [PATCH 10/15] stylistic fixes

---
 pandas/io/formats/excel.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/io/formats/excel.py b/pandas/io/formats/excel.py
index d467abcabfcf9..3482f0d8ee573 100644
--- a/pandas/io/formats/excel.py
+++ b/pandas/io/formats/excel.py
@@ -655,7 +655,8 @@ def write(self, writer, sheet_name='Sheet1', startrow=0,
         if num_rows > self.max_rows or num_cols > self.max_cols:
             raise ValueError("This sheet is too large! Your sheet size is: " +
                              "{}, {} ".format(num_rows, num_cols) +
-                             "Max sheet size is: {}, {}".format(self.max_rows, self.max_cols))
+                             "Max sheet size is: {}, {}".
+                             format(self.max_rows, self.max_cols))
 
         if isinstance(writer, ExcelWriter):
             need_save = False

From 66dbb5115ef4dc02ac20f61dbeccb546a9cc781a Mon Sep 17 00:00:00 2001
From: Alex Nordin <alexander.f.nordin+git@gmail.com>
Date: Sat, 18 May 2019 23:16:22 -0400
Subject: [PATCH 11/15] Formatting updates to pass lint tests

---
 pandas/io/formats/excel.py    | 4 ++--
 pandas/tests/io/test_excel.py | 6 ++++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/pandas/io/formats/excel.py b/pandas/io/formats/excel.py
index 3482f0d8ee573..abd5ebbdf69b0 100644
--- a/pandas/io/formats/excel.py
+++ b/pandas/io/formats/excel.py
@@ -343,7 +343,7 @@ class ExcelFormatter(object):
 
     max_rows = 2**20
     max_cols = 2**14
-            
+
     def __init__(self, df, na_rep='', float_format=None, cols=None,
                  header=True, index=True, index_label=None, merge_cells=False,
                  inf_rep='inf', style_converter=None):
@@ -650,7 +650,7 @@ def write(self, writer, sheet_name='Sheet1', startrow=0,
         """
         from pandas.io.excel import ExcelWriter
         from pandas.io.common import _stringify_path
-        
+
         num_rows, num_cols = self.df.shape
         if num_rows > self.max_rows or num_cols > self.max_cols:
             raise ValueError("This sheet is too large! Your sheet size is: " +
diff --git a/pandas/tests/io/test_excel.py b/pandas/tests/io/test_excel.py
index 86ad8172a4878..5eac43805c775 100644
--- a/pandas/tests/io/test_excel.py
+++ b/pandas/tests/io/test_excel.py
@@ -1212,7 +1212,9 @@ class and any subclasses, on account of the `autouse=True`
 class TestExcelWriter(_WriterBase):
     # Base class for test cases to run with different Excel writers.
 
-    def test_excel_sheet_size(self): 
+    def test_excel_sheet_size(self):
+
+        # GH 26080
         breaking_row_count = 2**20 + 1
         breaking_col_count = 2**14 + 1
         #purposely using two arrays to prevent memory issues while testing
@@ -1227,7 +1229,7 @@ def test_excel_sheet_size(self):
 
         with pytest.raises(ValueError, match=msg):
             col_df.to_excel(self.path)
-            
+
     def test_excel_sheet_by_name_raise(self, *_):
         import xlrd
 

From f152e2ee1105b4a75cb0f27d5a89411ad6aad4f0 Mon Sep 17 00:00:00 2001
From: Alex Nordin <alexander.f.nordin+git@gmail.com>
Date: Thu, 23 May 2019 13:48:16 -0400
Subject: [PATCH 12/15] Fix lint error and update whatsnew.

---
 doc/source/whatsnew/v0.25.0.rst | 1 +
 pandas/tests/io/test_excel.py   | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v0.25.0.rst b/doc/source/whatsnew/v0.25.0.rst
index 7b87f6a7f8d3c..4c07c40a74b0c 100644
--- a/doc/source/whatsnew/v0.25.0.rst
+++ b/doc/source/whatsnew/v0.25.0.rst
@@ -36,6 +36,7 @@ Other Enhancements
 - :class:`RangeIndex` has gained :attr:`~RangeIndex.start`, :attr:`~RangeIndex.stop`, and :attr:`~RangeIndex.step` attributes (:issue:`25710`)
 - :class:`datetime.timezone` objects are now supported as arguments to timezone methods and constructors (:issue:`25065`)
 - :meth:`DataFrame.query` and :meth:`DataFrame.eval` now supports quoting column names with backticks to refer to names with spaces (:issue:`6508`)
+- :meth:'DataFrame.to_excel' now performs input-checking.
 
 .. _whatsnew_0250.api_breaking:
 
diff --git a/pandas/tests/io/test_excel.py b/pandas/tests/io/test_excel.py
index 5eac43805c775..44647b8a8d0f3 100644
--- a/pandas/tests/io/test_excel.py
+++ b/pandas/tests/io/test_excel.py
@@ -1217,7 +1217,7 @@ def test_excel_sheet_size(self):
         # GH 26080
         breaking_row_count = 2**20 + 1
         breaking_col_count = 2**14 + 1
-        #purposely using two arrays to prevent memory issues while testing
+        # purposely using two arrays to prevent memory issues while testing
         row_arr = np.zeros(shape=(breaking_row_count, 1))
         col_arr = np.zeros(shape=(1, breaking_col_count))
         row_df = pd.DataFrame(row_arr)

From 4910e804613daf52259c21f350b5da476577bfc8 Mon Sep 17 00:00:00 2001
From: Alex Nordin <alexander.f.nordin+git@gmail.com>
Date: Fri, 24 May 2019 17:16:46 -0400
Subject: [PATCH 13/15] Rephrase whatsnew

---
 doc/source/whatsnew/v0.25.0.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v0.25.0.rst b/doc/source/whatsnew/v0.25.0.rst
index 4c07c40a74b0c..f3ff419a00035 100644
--- a/doc/source/whatsnew/v0.25.0.rst
+++ b/doc/source/whatsnew/v0.25.0.rst
@@ -36,7 +36,7 @@ Other Enhancements
 - :class:`RangeIndex` has gained :attr:`~RangeIndex.start`, :attr:`~RangeIndex.stop`, and :attr:`~RangeIndex.step` attributes (:issue:`25710`)
 - :class:`datetime.timezone` objects are now supported as arguments to timezone methods and constructors (:issue:`25065`)
 - :meth:`DataFrame.query` and :meth:`DataFrame.eval` now supports quoting column names with backticks to refer to names with spaces (:issue:`6508`)
-- :meth:'DataFrame.to_excel' now performs input-checking.
+- :meth:'DataFrame.to_excel' now raises a ``ValueError`` when the caller's dimensions exceed the limitations of Excel (:issue:`26051`)
 
 .. _whatsnew_0250.api_breaking:
 

From eff16185f412976119a6b78a3817945aaa289df0 Mon Sep 17 00:00:00 2001
From: Alex Nordin <alexander.f.nordin+git@gmail.com>
Date: Mon, 27 May 2019 20:06:44 -0400
Subject: [PATCH 14/15] Formatting fix

---
 doc/source/whatsnew/v0.25.0.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v0.25.0.rst b/doc/source/whatsnew/v0.25.0.rst
index f3ff419a00035..51379d3647506 100644
--- a/doc/source/whatsnew/v0.25.0.rst
+++ b/doc/source/whatsnew/v0.25.0.rst
@@ -36,7 +36,7 @@ Other Enhancements
 - :class:`RangeIndex` has gained :attr:`~RangeIndex.start`, :attr:`~RangeIndex.stop`, and :attr:`~RangeIndex.step` attributes (:issue:`25710`)
 - :class:`datetime.timezone` objects are now supported as arguments to timezone methods and constructors (:issue:`25065`)
 - :meth:`DataFrame.query` and :meth:`DataFrame.eval` now supports quoting column names with backticks to refer to names with spaces (:issue:`6508`)
-- :meth:'DataFrame.to_excel' now raises a ``ValueError`` when the caller's dimensions exceed the limitations of Excel (:issue:`26051`)
+- :meth:`DataFrame.to_excel` now raises a ``ValueError`` when the caller's dimensions exceed the limitations of Excel (:issue:`26051`)
 
 .. _whatsnew_0250.api_breaking:
 

From 66f4602f7ffaaf35a5430882937ba9030c6606fe Mon Sep 17 00:00:00 2001
From: Alex Nordin <alexander.f.nordin+git@gmail.com>
Date: Sat, 1 Jun 2019 08:43:27 -0400
Subject: [PATCH 15/15] whatsnew update

---
 doc/source/whatsnew/v0.25.0.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v0.25.0.rst b/doc/source/whatsnew/v0.25.0.rst
index 5b0f52ab13c83..1a0df4789f4c7 100644
--- a/doc/source/whatsnew/v0.25.0.rst
+++ b/doc/source/whatsnew/v0.25.0.rst
@@ -39,7 +39,6 @@ Other Enhancements
 - :class:`RangeIndex` has gained :attr:`~RangeIndex.start`, :attr:`~RangeIndex.stop`, and :attr:`~RangeIndex.step` attributes (:issue:`25710`)
 - :class:`datetime.timezone` objects are now supported as arguments to timezone methods and constructors (:issue:`25065`)
 - :meth:`DataFrame.query` and :meth:`DataFrame.eval` now supports quoting column names with backticks to refer to names with spaces (:issue:`6508`)
-- :meth:`DataFrame.to_excel` now raises a ``ValueError`` when the caller's dimensions exceed the limitations of Excel (:issue:`26051`)
 - :func:`merge_asof` now gives a more clear error message when merge keys are categoricals that are not equal (:issue:`26136`)
 - :meth:`pandas.core.window.Rolling` supports exponential (or Poisson) window type (:issue:`21303`)
 -
@@ -467,6 +466,7 @@ I/O
 - Fixed memory leak in :meth:`DataFrame.to_json` when dealing with numeric data (:issue:`24889`)
 - Bug in :func:`read_json` where date strings with ``Z`` were not converted to a UTC timezone (:issue:`26168`)
 - Added ``cache_dates=True`` parameter to :meth:`read_csv`, which allows to cache unique dates when they are parsed (:issue:`25990`)
+- :meth:`DataFrame.to_excel` now raises a ``ValueError`` when the caller's dimensions exceed the limitations of Excel (:issue:`26051`)
 
 Plotting
 ^^^^^^^^