92 lines
2.8 KiB
Python
92 lines
2.8 KiB
Python
|
import numpy as np
|
||
|
|
|
||
|
|
from pandas import (
|
||
|
|
DataFrame,
|
||
|
|
Index,
|
||
|
|
RangeIndex,
|
||
|
|
Series,
|
||
|
|
)
|
||
|
|
import pandas._testing as tm
|
||
|
|
|
||
|
|
# -----------------------------------------------------------------------------
|
||
|
|
# Copy/view behaviour for the values that are set in a DataFrame
|
||
|
|
|
||
|
|
|
||
|
|
def test_set_column_with_array():
|
||
|
|
# Case: setting an array as a new column (df[col] = arr) copies that data
|
||
|
|
df = DataFrame({"a": [1, 2, 3], "b": [4, 5, 6]})
|
||
|
|
arr = np.array([1, 2, 3], dtype="int64")
|
||
|
|
|
||
|
|
df["c"] = arr
|
||
|
|
|
||
|
|
# the array data is copied
|
||
|
|
assert not np.shares_memory(df["c"].values, arr)
|
||
|
|
# and thus modifying the array does not modify the DataFrame
|
||
|
|
arr[0] = 0
|
||
|
|
tm.assert_series_equal(df["c"], Series([1, 2, 3], name="c"))
|
||
|
|
|
||
|
|
|
||
|
|
def test_set_column_with_series(using_copy_on_write):
|
||
|
|
# Case: setting a series as a new column (df[col] = s) copies that data
|
||
|
|
df = DataFrame({"a": [1, 2, 3], "b": [4, 5, 6]})
|
||
|
|
ser = Series([1, 2, 3])
|
||
|
|
|
||
|
|
df["c"] = ser
|
||
|
|
|
||
|
|
if using_copy_on_write:
|
||
|
|
# TODO(CoW) with CoW we can delay the copy
|
||
|
|
# assert np.shares_memory(df["c"].values, ser.values)
|
||
|
|
assert not np.shares_memory(df["c"].values, ser.values)
|
||
|
|
else:
|
||
|
|
# the series data is copied
|
||
|
|
assert not np.shares_memory(df["c"].values, ser.values)
|
||
|
|
|
||
|
|
# and modifying the series does not modify the DataFrame
|
||
|
|
ser.iloc[0] = 0
|
||
|
|
assert ser.iloc[0] == 0
|
||
|
|
tm.assert_series_equal(df["c"], Series([1, 2, 3], name="c"))
|
||
|
|
|
||
|
|
|
||
|
|
def test_set_column_with_index(using_copy_on_write):
|
||
|
|
# Case: setting an index as a new column (df[col] = idx) copies that data
|
||
|
|
df = DataFrame({"a": [1, 2, 3], "b": [4, 5, 6]})
|
||
|
|
idx = Index([1, 2, 3])
|
||
|
|
|
||
|
|
df["c"] = idx
|
||
|
|
|
||
|
|
# the index data is copied
|
||
|
|
assert not np.shares_memory(df["c"].values, idx.values)
|
||
|
|
|
||
|
|
# and thus modifying the index does not modify the DataFrame
|
||
|
|
idx.values[0] = 0
|
||
|
|
tm.assert_series_equal(df["c"], Series([1, 2, 3], name="c"))
|
||
|
|
|
||
|
|
idx = RangeIndex(1, 4)
|
||
|
|
arr = idx.values
|
||
|
|
|
||
|
|
df["d"] = idx
|
||
|
|
|
||
|
|
assert not np.shares_memory(df["d"].values, arr)
|
||
|
|
arr[0] = 0
|
||
|
|
tm.assert_series_equal(df["d"], Series([1, 2, 3], name="d"))
|
||
|
|
|
||
|
|
|
||
|
|
def test_set_columns_with_dataframe(using_copy_on_write):
|
||
|
|
# Case: setting a DataFrame as new columns copies that data
|
||
|
|
df = DataFrame({"a": [1, 2, 3], "b": [4, 5, 6]})
|
||
|
|
df2 = DataFrame({"c": [7, 8, 9], "d": [10, 11, 12]})
|
||
|
|
|
||
|
|
df[["c", "d"]] = df2
|
||
|
|
|
||
|
|
if using_copy_on_write:
|
||
|
|
# TODO(CoW) with CoW we can delay the copy
|
||
|
|
# assert np.shares_memory(df["c"].values, df2["c"].values)
|
||
|
|
assert not np.shares_memory(df["c"].values, df2["c"].values)
|
||
|
|
else:
|
||
|
|
# the data is copied
|
||
|
|
assert not np.shares_memory(df["c"].values, df2["c"].values)
|
||
|
|
|
||
|
|
# and modifying the set DataFrame does not modify the original DataFrame
|
||
|
|
df2.iloc[0, 0] = 0
|
||
|
|
tm.assert_series_equal(df["c"], Series([7, 8, 9], name="c"))
|