test_reshape.py

import pytest
import numpy as np

import pandas as pd
import pandas.util.testing as tm


@pytest.fixture
def sparse_df():
    return pd.SparseDataFrame({0: {0: 1}, 1: {1: 1}, 2: {2: 1}})  # eye


@pytest.fixture
def multi_index3():
    return pd.MultiIndex.from_tuples([(0, 0), (1, 1), (2, 2)])


def test_sparse_frame_stack(sparse_df, multi_index3):
    ss = sparse_df.stack()
    expected = pd.SparseSeries(np.ones(3), index=multi_index3)
    tm.assert_sp_series_equal(ss, expected)


def test_sparse_frame_unstack(sparse_df):
    mi = pd.MultiIndex.from_tuples([(0, 0), (1, 0), (1, 2)])
    sparse_df.index = mi
    arr = np.array([[1, np.nan, np.nan],
                    [np.nan, 1, np.nan],
                    [np.nan, np.nan, 1]])
    unstacked_df = pd.DataFrame(arr, index=mi).unstack()
    unstacked_sdf = sparse_df.unstack()

    tm.assert_numpy_array_equal(unstacked_df.values, unstacked_sdf.values)


def test_sparse_series_unstack(sparse_df, multi_index3):
    frame = pd.SparseSeries(np.ones(3), index=multi_index3).unstack()
    tm.assert_sp_frame_equal(frame, sparse_df)