ERR: better error message on too large excel sheet

pandas/core/generic.py

@@ -2146,6 +2146,7 @@ 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

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 = 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) +
+                             "Max sheet size is: {}, {}".format(excel_max_rows, excel_max_cols))
 
         if isinstance(writer, ExcelWriter):
             need_save = False

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