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- import numpy as np
- from pandas import DataFrame
- import pandas._testing as tm
- def test_head_tail_generic(index, frame_or_series):
- # GH#5370
- ndim = 2 if frame_or_series is DataFrame else 1
- shape = (len(index),) * ndim
- vals = np.random.randn(*shape)
- obj = frame_or_series(vals, index=index)
- tm.assert_equal(obj.head(), obj.iloc[:5])
- tm.assert_equal(obj.tail(), obj.iloc[-5:])
- # 0-len
- tm.assert_equal(obj.head(0), obj.iloc[0:0])
- tm.assert_equal(obj.tail(0), obj.iloc[0:0])
- # bounded
- tm.assert_equal(obj.head(len(obj) + 1), obj)
- tm.assert_equal(obj.tail(len(obj) + 1), obj)
- # neg index
- tm.assert_equal(obj.head(-3), obj.head(len(index) - 3))
- tm.assert_equal(obj.tail(-3), obj.tail(len(index) - 3))
- def test_head_tail(float_frame):
- tm.assert_frame_equal(float_frame.head(), float_frame[:5])
- tm.assert_frame_equal(float_frame.tail(), float_frame[-5:])
- tm.assert_frame_equal(float_frame.head(0), float_frame[0:0])
- tm.assert_frame_equal(float_frame.tail(0), float_frame[0:0])
- tm.assert_frame_equal(float_frame.head(-1), float_frame[:-1])
- tm.assert_frame_equal(float_frame.tail(-1), float_frame[1:])
- tm.assert_frame_equal(float_frame.head(1), float_frame[:1])
- tm.assert_frame_equal(float_frame.tail(1), float_frame[-1:])
- # with a float index
- df = float_frame.copy()
- df.index = np.arange(len(float_frame)) + 0.1
- tm.assert_frame_equal(df.head(), df.iloc[:5])
- tm.assert_frame_equal(df.tail(), df.iloc[-5:])
- tm.assert_frame_equal(df.head(0), df[0:0])
- tm.assert_frame_equal(df.tail(0), df[0:0])
- tm.assert_frame_equal(df.head(-1), df.iloc[:-1])
- tm.assert_frame_equal(df.tail(-1), df.iloc[1:])
- def test_head_tail_empty():
- # test empty dataframe
- empty_df = DataFrame()
- tm.assert_frame_equal(empty_df.tail(), empty_df)
- tm.assert_frame_equal(empty_df.head(), empty_df)
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