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BUG: Nrows cannot be zero for read_csv. Fixes #21141 #21431

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BUG: Nrows cannot be zero for read_csv. Fixes #21141 #21431

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BUG: Nrows cannot be zero for read_csv. Fixes #21141
cgopalan Jun 11, 2018
947168b
Corrected issue number
cgopalan Jun 11, 2018
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2 changes: 1 addition & 1 deletion pandas/io/parsers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1027,7 +1027,7 @@ def _failover_to_python(self):
raise com.AbstractMethodError(self)

def read(self, nrows=None):
nrows = _validate_integer('nrows', nrows)
nrows = _validate_integer('nrows', nrows, min_val=1)

if nrows is not None:
if self.options.get('skipfooter'):
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5 changes: 4 additions & 1 deletion pandas/tests/io/parser/common.py
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Expand Up @@ -364,7 +364,7 @@ def test_read_nrows(self):
df = self.read_csv(StringIO(self.data1), nrows=3.0)
tm.assert_frame_equal(df, expected)

msg = r"'nrows' must be an integer >=0"
msg = r"'nrows' must be an integer >=1"

with tm.assert_raises_regex(ValueError, msg):
self.read_csv(StringIO(self.data1), nrows=1.2)
Expand All @@ -375,6 +375,9 @@ def test_read_nrows(self):
with tm.assert_raises_regex(ValueError, msg):
self.read_csv(StringIO(self.data1), nrows=-1)

with tm.assert_raises_regex(ValueError, msg):
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Can you reference the issue number in a comment above this line.

self.read_csv(StringIO(self.data1), nrows=0)

def test_read_chunksize(self):
reader = self.read_csv(StringIO(self.data1), index_col=0, chunksize=2)
df = self.read_csv(StringIO(self.data1), index_col=0)
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9 changes: 8 additions & 1 deletion pandas/tests/io/test_excel.py
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Expand Up @@ -995,11 +995,18 @@ def test_read_excel_nrows_greater_than_nrows_in_file(self, ext):

def test_read_excel_nrows_non_integer_parameter(self, ext):
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Would be better to parametrize this test for cases like [-1, 0, '1'] instead of having separate tests

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@WillAyd sure, I will make these changes as soon as we decide if we are keeping this PR :)

# GH 16645
msg = "'nrows' must be an integer >=0"
msg = "'nrows' must be an integer >=1"
with tm.assert_raises_regex(ValueError, msg):
pd.read_excel(os.path.join(self.dirpath, 'test1' + ext),
nrows='5')

def test_read_excel_nrows_zero_parameter(self, ext):
# GH 21141
msg = "'nrows' must be an integer >=1"
with tm.assert_raises_regex(ValueError, msg):
pd.read_excel(os.path.join(self.dirpath, 'test1' + ext),
nrows=0)

def test_read_excel_squeeze(self, ext):
# GH 12157
f = os.path.join(self.dirpath, 'test_squeeze' + ext)
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