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"""
test_insert is specifically for the DataFrame.insert method; not to be
confused with tests with "insert" in their names that are really testing
__setitem__.
"""
import numpy as np
import pytest
from pandas.errors import PerformanceWarning
from pandas import (
DataFrame,
Index,
)
import pandas._testing as tm
class TestDataFrameInsert:
def test_insert(self):
df = DataFrame(
np.random.default_rng(2).standard_normal((5, 3)),
index=np.arange(5),
columns=["c", "b", "a"],
)
df.insert(0, "foo", df["a"])
tm.assert_index_equal(df.columns, Index(["foo", "c", "b", "a"]))
tm.assert_series_equal(df["a"], df["foo"], check_names=False)
df.insert(2, "bar", df["c"])
tm.assert_index_equal(df.columns, Index(["foo", "c", "bar", "b", "a"]))
tm.assert_almost_equal(df["c"], df["bar"], check_names=False)
with pytest.raises(ValueError, match="already exists"):
df.insert(1, "a", df["b"])
msg = "cannot insert c, already exists"
with pytest.raises(ValueError, match=msg):
df.insert(1, "c", df["b"])
df.columns.name = "some_name"
# preserve columns name field
df.insert(0, "baz", df["c"])
assert df.columns.name == "some_name"
def test_insert_column_bug_4032(self):
# GH#4032, inserting a column and renaming causing errors
df = DataFrame({"b": [1.1, 2.2]})
df = df.rename(columns={})
df.insert(0, "a", [1, 2])
result = df.rename(columns={})
expected = DataFrame([[1, 1.1], [2, 2.2]], columns=["a", "b"])
tm.assert_frame_equal(result, expected)
df.insert(0, "c", [1.3, 2.3])
result = df.rename(columns={})
expected = DataFrame([[1.3, 1, 1.1], [2.3, 2, 2.2]], columns=["c", "a", "b"])
tm.assert_frame_equal(result, expected)
def test_insert_with_columns_dups(self):
# GH#14291
df = DataFrame()
df.insert(0, "A", ["g", "h", "i"], allow_duplicates=True)
df.insert(0, "A", ["d", "e", "f"], allow_duplicates=True)
df.insert(0, "A", ["a", "b", "c"], allow_duplicates=True)
exp = DataFrame(
[["a", "d", "g"], ["b", "e", "h"], ["c", "f", "i"]], columns=["A", "A", "A"]
)
tm.assert_frame_equal(df, exp)
def test_insert_item_cache(self, using_array_manager, using_copy_on_write):
df = DataFrame(np.random.default_rng(2).standard_normal((4, 3)))
ser = df[0]
if using_array_manager:
expected_warning = None
else:
# with BlockManager warn about high fragmentation of single dtype
expected_warning = PerformanceWarning
with tm.assert_produces_warning(expected_warning):
for n in range(100):
df[n + 3] = df[1] * n
if using_copy_on_write:
ser.iloc[0] = 99
assert df.iloc[0, 0] == df[0][0]
assert df.iloc[0, 0] != 99
else:
ser.values[0] = 99
assert df.iloc[0, 0] == df[0][0]
assert df.iloc[0, 0] == 99
def test_insert_EA_no_warning(self):
# PerformanceWarning about fragmented frame should not be raised when
# using EAs (https://github.com/pandas-dev/pandas/issues/44098)
df = DataFrame(
np.random.default_rng(2).integers(0, 100, size=(3, 100)), dtype="Int64"
)
with tm.assert_produces_warning(None):
df["a"] = np.array([1, 2, 3])
def test_insert_frame(self):
# GH#42403
df = DataFrame({"col1": [1, 2], "col2": [3, 4]})
msg = (
"Expected a one-dimensional object, got a DataFrame with 2 columns instead."
)
with pytest.raises(ValueError, match=msg):
df.insert(1, "newcol", df)
def test_insert_int64_loc(self):
# GH#53193
df = DataFrame({"a": [1, 2]})
df.insert(np.int64(0), "b", 0)
tm.assert_frame_equal(df, DataFrame({"b": [0, 0], "a": [1, 2]}))