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"""
Tests that work on both the Python and C engines but do not have a
specific classification into the other test modules.
"""
from io import StringIO
import pytest
from pandas import (
DataFrame,
concat,
)
import pandas._testing as tm
pytestmark = pytest.mark.usefixtures("pyarrow_skip")
def test_iterator(all_parsers):
# see gh-6607
data = """index,A,B,C,D
foo,2,3,4,5
bar,7,8,9,10
baz,12,13,14,15
qux,12,13,14,15
foo2,12,13,14,15
bar2,12,13,14,15
"""
parser = all_parsers
kwargs = {"index_col": 0}
expected = parser.read_csv(StringIO(data), **kwargs)
with parser.read_csv(StringIO(data), iterator=True, **kwargs) as reader:
first_chunk = reader.read(3)
tm.assert_frame_equal(first_chunk, expected[:3])
last_chunk = reader.read(5)
tm.assert_frame_equal(last_chunk, expected[3:])
def test_iterator2(all_parsers):
parser = all_parsers
data = """A,B,C
foo,1,2,3
bar,4,5,6
baz,7,8,9
"""
with parser.read_csv(StringIO(data), iterator=True) as reader:
result = list(reader)
expected = DataFrame(
[[1, 2, 3], [4, 5, 6], [7, 8, 9]],
index=["foo", "bar", "baz"],
columns=["A", "B", "C"],
)
tm.assert_frame_equal(result[0], expected)
def test_iterator_stop_on_chunksize(all_parsers):
# gh-3967: stopping iteration when chunksize is specified
parser = all_parsers
data = """A,B,C
foo,1,2,3
bar,4,5,6
baz,7,8,9
"""
with parser.read_csv(StringIO(data), chunksize=1) as reader:
result = list(reader)
assert len(result) == 3
expected = DataFrame(
[[1, 2, 3], [4, 5, 6], [7, 8, 9]],
index=["foo", "bar", "baz"],
columns=["A", "B", "C"],
)
tm.assert_frame_equal(concat(result), expected)
@pytest.mark.parametrize(
"kwargs", [{"iterator": True, "chunksize": 1}, {"iterator": True}, {"chunksize": 1}]
)
def test_iterator_skipfooter_errors(all_parsers, kwargs):
msg = "'skipfooter' not supported for iteration"
parser = all_parsers
data = "a\n1\n2"
with pytest.raises(ValueError, match=msg):
with parser.read_csv(StringIO(data), skipfooter=1, **kwargs) as _:
pass
def test_iteration_open_handle(all_parsers):
parser = all_parsers
kwargs = {"header": None}
with tm.ensure_clean() as path:
with open(path, "w", encoding="utf-8") as f:
f.write("AAA\nBBB\nCCC\nDDD\nEEE\nFFF\nGGG")
with open(path, encoding="utf-8") as f:
for line in f:
if "CCC" in line:
break
result = parser.read_csv(f, **kwargs)
expected = DataFrame({0: ["DDD", "EEE", "FFF", "GGG"]})
tm.assert_frame_equal(result, expected)