test_tables.py

import doctest
import re
import pytest
import numpy as np
from numpy.testing import assert_array_equal
from datascience import *
import pandas as pd


#########
# Utils #
#########


@pytest.fixture(scope='function')
def table():
    """Setup Scrabble table"""
    return Table().with_columns([
        'letter', ['a', 'b', 'c', 'z'],
        'count', [9, 3, 3, 1],
        'points', [1, 2, 2, 10],
        ])


@pytest.fixture(scope='function')
def table2():
    """Setup second table"""
    return Table().with_columns([
        ['points', (1, 2, 3)],
        ['names', ('one', 'two', 'three')],
        ])


@pytest.fixture(scope='function')
def table3():
    """Setup third table; same labels as first but in a different order."""
    return Table().with_columns([
        'count', [0, 54, 5],
        'points', [3, 10, 24],
        'letter', ['x', 'y', 'z'],
        ])


@pytest.fixture(scope='function')
def numbers_table():
    """Setup table containing only numbers"""
    return Table().with_columns([
        'count', [9, 3, 3, 1],
        'points', [1, 2, 2, 10],
        ])

@pytest.fixture(scope='function')
def categories_table():
    """Setup a table with a column to serve as pivot keys and
    a columns of values to bin for each key."""
    return Table(['key', 'val']).with_rows([
            ['a', 1],
            ['a', 1],
            ['a', 2],
            ['b', 1],
            ['b', 2],
            ['b', 2]])

@pytest.fixture(scope='module')
def t():
    """Create one table for entire module"""
    return table()


@pytest.fixture(scope='module')
def u():
    """Setup second alphanumeric table"""
    return table2()


def assert_equal(string1, string2):
    string1, string2 = str(string1), str(string2)
    whitespace = re.compile('\s')
    purify = lambda s: whitespace.sub('', s)
    assert purify(string1) == purify(string2), "\n%s\n!=\n%s" % (string1, string2)


############
# Doctests #
############


def test_doctests():
    results = doctest.testmod(tables, optionflags=doctest.NORMALIZE_WHITESPACE)
    assert results.failed == 0


############
# Overview #
############


def test_basic(t):
    """Tests that t works"""
    assert_equal(t, """
    letter | count | points
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    """)

def test_column(table):
    """Test table.values()"""
    assert_array_equal(table.column('letter'), np.array(['a', 'b', 'c', 'z']))
    assert_array_equal(table.column(1), np.array([9, 3, 3, 1]))


def test_basic_points(t):
    assert_array_equal(t['points'], np.array([1, 2, 2, 10]))


def test_basic_rows(t):
    assert_equal(
        t.rows[2],
        "Row(letter='c', count=3, points=2)")

def test_select(t):
    test = t.select(['points', 1]).cumsum()
    assert_equal(test, """
    points | count
    1      | 9
    3      | 12
    5      | 15
    15     | 16
    """)

def test_drop(t):
    test = t.drop(['points', 1])
    assert_equal(test, """
    letter
    a
    b
    c
    z
    """)

def test_take(t):
    test = t.take([1, 2])
    assert_equal(test, """
    letter | count | points
    b      | 3     | 2
    c      | 3     | 2
    """)


def test_take_slice(t):
    test = t.take[1:3]
    assert_equal(test, """
    letter | count | points
    b      | 3     | 2
    c      | 3     | 2
    """)


def test_take_slice_single(t):
    test = t.take[1]
    assert_equal(test, """
    letter | count | points
    b      | 3     | 2
    """)


def test_take_iterable(t):
    test = t.take[0, 2]
    assert_equal(test, """
    letter | count | points
    a      | 9     | 1
    c      | 3     | 2
    """)


def test_exclude(t):
    test = t.exclude([1, 3])
    assert_equal(test, """
    letter | count | points
    a      | 9     | 1
    c      | 3     | 2
    """)


def test_exclude_slice(t):
    test = t.exclude[1:3]
    assert_equal(test, """
    letter | count | points
    a      | 9     | 1
    z      | 1     | 10
    """)


def test_exclude_slice_single(t):
    test = t.exclude[1]
    assert_equal(test, """
    letter | count | points
    a      | 9     | 1
    c      | 3     | 2
    z      | 1     | 10
    """)


def test_exclude_iterable(t):
    test = t.exclude[0, 2]
    assert_equal(test, """
    letter | count | points
    b      | 3     | 2
    z      | 1     | 10
    """)


def test_stats(t):
    test = t.stats()
    assert_equal(test, """
    statistic | letter | count | points
    min       | a      | 1     | 1
    max       | z      | 9     | 10
    median    |        | 3     | 2
    sum       |        | 16    | 15
    """)


def test_stats_with_numpy(t):
    test = t.stats([np.mean, np.std, np.var])
    assert_equal(test, """
    statistic | letter | count | points
    mean      |        | 4     | 3.75
    std       |        | 3     | 3.63146
    var       |        | 9     | 13.1875""")


def test_where(t):
    test = t.where('points', 2)
    assert_equal(test, """
    letter | count | points
    b      | 3     | 2
    c      | 3     | 2
    """)
    test = t.where(2, 2)
    assert_equal(test, """
    letter | count | points
    b      | 3     | 2
    c      | 3     | 2
    """)


def test_where_conditions(t):
    t['totals'] = t['points'] * t['count']
    test = t.where(t['totals'] > 8)
    assert_equal(test, """
    letter | count | points | totals
    a      | 9     | 1      | 9
    z      | 1     | 10     | 10
    """)


def test_where_predicates(t):
    t['totals'] = t['points'] * t['count']
    test = t.where('totals', are.between(9, 11))
    assert_equal(test, """
    letter | count | points | totals
    a      | 9     | 1      | 9
    z      | 1     | 10     | 10
    """)


def test_sort(t):
    test = t.sort('points')
    assert_equal(test, """
    letter | count | points | totals
    a      | 9     | 1      | 9
    b      | 3     | 2      | 6
    c      | 3     | 2      | 6
    z      | 1     | 10     | 10
    """)
    test = t.sort(3)
    assert_equal(test, """
    letter | count | points | totals
    b      | 3     | 2      | 6
    c      | 3     | 2      | 6
    a      | 9     | 1      | 9
    z      | 1     | 10     | 10
    """)


def test_sort_args(t):
    test = t.sort('points', descending=True, distinct=True)
    assert_equal(test, """
    letter | count | points | totals
    z      | 1     | 10     | 10
    b      | 3     | 2      | 6
    a      | 9     | 1      | 9
    """)


def test_sort_syntax(t):
    test = t.sort(-t['totals'])
    assert_equal(test, """
    letter | count | points | totals
    z      | 1     | 10     | 10
    a      | 9     | 1      | 9
    b      | 3     | 2      | 6
    c      | 3     | 2      | 6
    """)


def test_group(t):
    test = t.group('points')
    assert_equal(test, """
    points | count
    1      | 1
    2      | 2
    10     | 1
    """)
    test = t.group(2)
    assert_equal(test, """
    points | count
    1      | 1
    2      | 2
    10     | 1
    """)


def test_group_with_func(t):
    test = t.group('points', sum)
    assert_equal(test, """
    points | letter sum | count sum | totals sum
    1      |            | 9         | 9
    2      |            | 6         | 12
    10     |            | 1         | 10
    """)


def test_groups(t):
    t = t.copy()
    t.append(('e', 12, 1, 12))
    t['early'] = t['letter'] < 'd'
    test = t.groups(['points', 'early'])
    assert_equal(test, """
    points | early | count
    1      | False | 1
    1      | True  | 1
    2      | True  | 2
    10     | False | 1
    """)


def test_groups_list(t):
    t = t.copy()
    t.append(('e', 12, 1, 12))
    t['early'] = t['letter'] < 'd'
    test = t.groups(['points', 'early'], lambda s: s)
    assert_equal(test, """
    points | early | letter    | count | totals
    1      | False | ['e']     | [12]  | [12]
    1      | True  | ['a']     | [9]   | [9]
    2      | True  | ['b' 'c'] | [3 3] | [6 6]
    10     | False | ['z']     | [1]   | [10]
    """)


def test_groups_collect(t):
    t = t.copy()
    t.append(('e', 12, 1, 12))
    t['early'] = t['letter'] < 'd'
    test = t.select(['points', 'early', 'count']).groups(['points', 'early'], sum)
    assert_equal(test, """
    points | early | count sum
    1      | False | 12
    1      | True  | 9
    2      | True  | 6
    10     | False | 1
    """)


def test_join(t, u):
    """Tests that join works, not destructive"""
    test = t.join('points', u)
    assert_equal(test, """
    points | letter | count | totals | names
    1      | a      | 9     | 9      | one
    2      | b      | 3     | 6      | two
    2      | c      | 3     | 6      | two
    """)
    assert_equal(u, """
    points  | names
    1       | one
    2       | two
    3       | three
    """)
    assert_equal(t, """
    letter | count | points | totals
    a      | 9     | 1      | 9
    b      | 3     | 2      | 6
    c      | 3     | 2      | 6
    z      | 1     | 10     | 10
    """)


def test_pivot_counts(t):
    t = t.copy()
    t.append(('e', 12, 1, 12))
    t['early'] = t['letter'] < 'd'
    test = t.pivot('points', 'early')
    assert_equal(test, """
    early | 1 | 2 | 10
    False | 1 | 0 | 1
    True  | 1 | 2 | 0
    """)


def test_pivot_values(t):
    t = t.copy()
    t.append(('e', 12, 1, 12))
    t['early'] = t['letter'] < 'd'
    t['exists'] = 2
    summed = t.pivot('points', 'early', 'exists', sum)
    assert_equal(summed, """
    early | 1 | 2 | 10
    False | 2 | 0 | 2
    True  | 2 | 4 | 0
    """)
    maxed = t.pivot('points', 'early', 'exists', max, -1)
    assert_equal(maxed, """
    early | 1 | 2  | 10
    False | 2 | -1 | 2
    True  | 2 | 2  | -1
    """)


def test_pivot_multiple_rows(t):
    t = t.copy()
    t.append(('e', 12, 1, 12))
    t['early'] = t['letter'] < 'd'
    t['late'] = t['letter'] > 'c'
    t['exists'] = 1
    test = t.pivot('points', ['early', 'late'], 'exists', sum)
    assert_equal(test, """
    early | late  | 1 | 2 | 10
    False | True  | 1 | 0 | 1
    True  | False | 1 | 2 | 0
    """)


def test_pivot_sum(t):
    t = t.copy()
    t.append(('e', 12, 1, 12))
    t['early'] = t['letter'] < 'd'
    t['exists'] = 1
    test = t.pivot('points', 'early', 'exists', sum)
    assert_equal(test, """
    early | 1 | 2 | 10
    False | 1 | 0 | 1
    True  | 1 | 2 | 0
    """)


def test_apply(t):
    t = t.copy()
    assert_array_equal(t.apply(lambda x, y: x * y, ['count', 'points']), np.array([9, 6, 6, 10]))
    assert_array_equal(t.apply(lambda x: x * x, 'points'), np.array([1, 4, 4, 100]))
    assert_array_equal(t.apply(lambda row: row.item('count') * 2), np.array([18, 6, 6, 2]))
    with(pytest.raises(ValueError)):
        t.apply(lambda x, y: x + y, ['count', 'score'])


########
# Init #
########


def test_tuples(t, u):
    """Tests that different-sized tuples are allowed."""
    different = [((5, 1), (1, 2, 2, 10)), ('short', 'long')]
    t = Table(different, ['tuple', 'size'])
    assert_equal(t, """
    tuple         | size
    (5, 1)        | short
    (1, 2, 2, 10) | long
    """)
    same = [((5, 4, 3, 1), (1, 2, 2, 10)), ('long', 'long')]
    u = Table(same, ['tuple', 'size'])
    assert_equal(u, """
    tuple         | size
    [5 4 3 1]     | long
    [ 1  2  2 10] | long
    """)


def test_keys_and_values():
    """Tests that a table can be constructed from keys and values."""
    d = {1: 2, 3: 4}
    t = Table([d.keys(), d.values()], ['keys', 'values'])
    assert_equal(t, """
    keys | values
    1    | 2
    3    | 4
    """)


##########
# Modify #
##########


def test_move_to_start(table):
    assert table.column_labels == ('letter', 'count', 'points')
    table.move_to_start('points')
    assert table.column_labels == ('points', 'letter', 'count')


def test_move_to_end(table):
    assert table.column_labels == ('letter', 'count', 'points')
    table.move_to_end('letter')
    assert table.column_labels == ('count', 'points', 'letter')


def test_append_row(table):
    row = ['g', 2, 2]
    table.append(row)
    assert_equal(table, """
    letter | count | points
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    g      | 2     | 2
    """)


def test_append_row_different_num_cols(table):
    """Makes sure that any incoming row must have the same amount of columns as the table."""
    row = "abcd"
    with(pytest.raises(Exception)):
        table.append(row)

    row = ["e", 2, 4, 6]
    with(pytest.raises(Exception)):
        table.append(row)


def test_append_column(table):
    column_1 = [10, 20, 30, 40]
    column_2 = 'hello'
    table.append_column('new_col1', column_1)
    assert_equal(table, """
    letter | count | points | new_col1
    a      | 9     | 1      | 10
    b      | 3     | 2      | 20
    c      | 3     | 2      | 30
    z      | 1     | 10     | 40
    """)
    table.append_column('new_col2', column_2)
    print(table)
    assert_equal(table, """
    letter | count | points | new_col1 | new_col2
    a      | 9     | 1      | 10       | hello
    b      | 3     | 2      | 20       | hello
    c      | 3     | 2      | 30       | hello
    z      | 1     | 10     | 40       | hello
    """)

    with(pytest.raises(ValueError)):
        table.append_column('bad_col', [1, 2])
    with(pytest.raises(ValueError)):
        table.append_column(0, [1, 2, 3, 4])

def test_with_column(table):
    column_1 = [10, 20, 30, 40]
    column_2 = 'hello'
    table2 = table.with_column('new_col1', column_1)
    table3 = table2.with_column('new_col2', column_2)
    assert_equal(table, """
    letter | count | points
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    """)
    assert_equal(table2, """
    letter | count | points | new_col1
    a      | 9     | 1      | 10
    b      | 3     | 2      | 20
    c      | 3     | 2      | 30
    z      | 1     | 10     | 40
    """)
    assert_equal(table3, """
    letter | count | points | new_col1 | new_col2
    a      | 9     | 1      | 10       | hello
    b      | 3     | 2      | 20       | hello
    c      | 3     | 2      | 30       | hello
    z      | 1     | 10     | 40       | hello
    """)

    with(pytest.raises(ValueError)):
        table.append_column('bad_col', [1, 2])
    with(pytest.raises(ValueError)):
        table.append_column(0, [1, 2, 3, 4])


def test_append_table(table):
    table.append(table)
    assert_equal(table, """
    letter | count | points
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    """)


def test_append_different_table(table, u):
    with pytest.raises(ValueError):
        table.append(u)


def test_append_different_order(table, table3):
    """Tests append with same columns, diff order"""
    table.append(table3)
    assert_equal(table, """
    letter | count | points
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    x      | 0     | 3
    y      | 54    | 10
    z      | 5     | 24
    """)


def test_relabel():
    table = Table([(1, 2, 3), (12345, 123, 5123)], ['points', 'id'])
    table.relabel('id', 'todo')
    assert_equal(table, """
    points | todo
    1      | 12345
    2      | 123
    3      | 5123
    """)
    table.relabel(1, 'yolo')
    assert_equal(table, """
    points | yolo
    1      | 12345
    2      | 123
    3      | 5123
    """)
    table.relabel(['points', 'yolo'], ['red', 'blue'])
    assert_equal(table, """
    red    | blue
    1      | 12345
    2      | 123
    3      | 5123
    """)
    with(pytest.raises(ValueError)):
        table.relabel(['red', 'blue'], ['magenta', 'cyan', 'yellow'])
    with(pytest.raises(ValueError)):
        table.relabel(['red', 'green'], ['magenta', 'yellow'])



def test_relabel_with_chars(table):
    assert_equal(table, """
    letter | count | points
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    """)
    table.relabel('points', 'minions')
    assert_equal(table, """
    letter | count | minions
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    """)

def test_with_relabeling(table):
    table2 = table.with_relabeling('points', 'minions')
    assert_equal(table2, """
    letter | count | minions
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    """)
    table3 = table.with_relabeling(['count', 'points'], ['ducks', 'ducklings'])
    assert_equal(table3, """
    letter | ducks | ducklings
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    """)
    assert_equal(table, """
    letter | count | points
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    """)

def test_bin(table):
    binned = table.bin('count')
    assert_equal(binned.take(np.arange(5)), """
    bin  | count count
    1    | 1
    1.8  | 0
    2.6  | 2
    3.4  | 0
    4.2  | 0
    """)
    binned = table.select([1, 2]).bin(bins=4)
    assert_equal(binned, """
    bin  | count count | points count
    1    | 3           | 3
    3.25 | 0           | 0
    5.5  | 0           | 0
    7.75 | 1           | 1
    10   | 0           | 0
    """)
    binned = table.bin('points', bins=[-1, 1, 3, 5, 7, 9, 11, 13])
    assert_equal(binned, """
    bin  | points count
    -1   | 0
    1    | 3
    3    | 0
    5    | 0
    7    | 0
    9    | 1
    11   | 0
    13   | 0
    """)

def test_remove_multiple(table):
    table.remove([1, 3])
    assert_equal(table, """
    letter | count | points
    a      | 9     | 1
    c      | 3     | 2
    """)

def test_remove_single(table):
    table.remove(1)
    assert_equal(table, """
    letter | count | points
    a      | 9     | 1
    c      | 3     | 2
    z      | 1     | 10
    """)


##########
# Create #
##########


def test_empty():
    t = Table.empty(['letter', 'count', 'points'])
    assert_equal(t, """
    letter | count | points
    """)

def test_empty_without_labels():
    t = Table.empty()
    assert_equal(t, '')


def test_from_rows():
    letters = [('a', 9, 1), ('b', 3, 2), ('c', 3, 2), ('z', 1, 10)]
    t = Table.from_rows(letters, ['letter', 'count', 'points'])
    assert_equal(t, """
    letter | count | points
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    """)


def test_from_records():
    letters = [
        {'letter': 'a',
         'count': 9,
         'points': 1,
        },
        {'letter': 'b',
         'count': 3,
         'points': 2,
        },
        {'letter': 'c',
         'count': 3,
         'points': 2,
        },
        {'letter': 'z',
         'count': 1,
         'points': 10,
        },
    ]
    t = Table.from_records(letters)
    assert_equal(t.select(['letter', 'count', 'points']), """
    letter | count | points
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    """)


def test_from_columns_dict():
    columns_dict = {
        'letter': ['a', 'b', 'c', 'z'],
        'count': [9, 3, 3, 1],
        'points': [1, 2, 2, 10]
    }
    t = Table.from_columns_dict(columns_dict)
    assert_equal(t.select(['letter', 'count', 'points']), """
    letter | count | points
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    """)


#############
# Transform #
#############


def test_group_by_tuples():
    tuples = [((5, 1), (1, 2, 2, 10), (1, 2, 2, 10)), (3, 3, 1)]
    t = Table(tuples, ['tuples', 'ints'])
    assert_equal(t, """
    tuples        | ints
    (5, 1)        | 3
    (1, 2, 2, 10) | 3
    (1, 2, 2, 10) | 1
    """)
    table = t.group('tuples', lambda s: s)
    assert_equal(table, """
    tuples        | ints
    (1, 2, 2, 10) | [3 1]
    (5, 1)        | [3]
    """)


def test_group_no_new_column(table):
    table.group(table.columns[1])
    assert_equal(table, """
    letter | count | points
    a      | 9     | 1
    b      | 3     | 2
    c      | 3     | 2
    z      | 1     | 10
    """)


def test_stack(table):
    test = table.stack(key='letter')
    assert_equal(test, """
    letter | column | value
    a      | count  | 9
    a      | points | 1
    b      | count  | 3
    b      | points | 2
    c      | count  | 3
    c      | points | 2
    z      | count  | 1
    z      | points | 10
    """)


def test_stack_restrict_columns(table):
    test = table.stack('letter', ['count'])
    assert_equal(test, """
    letter | column | value
    a      | count  | 9
    b      | count  | 3
    c      | count  | 3
    z      | count  | 1
    """)


def test_join_basic(table, table2):
    table['totals'] = table['points'] * table['count']
    test = table.join('points', table2)
    assert_equal(test, """
    points | letter | count | totals | names
    1      | a      | 9     | 9      | one
    2      | b      | 3     | 6      | two
    2      | c      | 3     | 6      | two
    """)


def test_join_with_booleans(table, table2):
    table['totals'] = table['points'] * table['count']
    table['points'] = table['points'] > 1
    table2['points'] = table2['points'] > 1

    assert_equal(table, """
    letter | count | points | totals
    a      | 9     | False  | 9
    b      | 3     | True   | 6
    c      | 3     | True   | 6
    z      | 1     | True   | 10
    """)

    assert_equal(table2, """
    points | names
    False  | one
    True   | two
    True   | three
    """)

    test = table.join('points', table2)
    assert_equal(test, """
    points | letter | count | totals | names
    False  | a      | 9     | 9      | one
    True   | b      | 3     | 6      | two
    True   | c      | 3     | 6      | two
    True   | z      | 1     | 10     | two
    """)


def test_join_with_self(table):
    test = table.join('count', table)
    assert_equal(test, """
    count | letter | points | letter_2 | points_2
    1     | z      | 10     | z        | 10
    3     | b      | 2      | b        | 2
    3     | c      | 2      | b        | 2
    9     | a      | 1      | a        | 1
    """)


def test_join_with_strings(table):
    test = table.join('letter', table)
    assert_equal(test, """
    letter | count | points | count_2 | points_2
    a      | 9     | 1      | 9       | 1
    b      | 3     | 2      | 3       | 2
    c      | 3     | 2      | 3       | 2
    z      | 1     | 10     | 1       | 10
    """)

def test_percentile(numbers_table):
    assert_equal(numbers_table.percentile(76), """
    count | points
    9     | 10
    """)

    assert_equal(numbers_table.percentile(75), """
    count | points
    3     | 2
    """)

def test_pivot_bin(categories_table):
    assert_equal(categories_table.pivot_bin('key', 'val', bins=[0, 1, 2, 3]), """
    bin  | a    | b
    0    | 0    | 0
    1    | 2    | 1
    2    | 1    | 2
    3    | 0    | 0
    """)

##################
# Export/Display #
##################


def test_format_function(table):
    """Test that formatting can be applied by a function."""
    table = table.copy().set_format('points', lambda v: float(v))
    assert_equal(table, """
    letter | count | points
    a      | 9     | 1.0
    b      | 3     | 2.0
    c      | 3     | 2.0
    z      | 1     | 10.0
    """)


def test_sample_basic(table):
    """Tests that sample doesn't break"""
    table.sample(table.num_rows)


def test_sample_basic_modk(table):
    """Tests that sample k<n doesn't break"""
    table.sample(2)


def test_sample_wrepl_basic(table):
    """Tests that sample with_replacement=True doesn't break"""
    table.sample(table.num_rows, with_replacement=True)


def test_sample_wwgts_basic(table):
    """Tests that sample with weights doesn't break"""
    table.sample(table.num_rows, weights=[1/4]*4)


def test_sample_weights_ne1(table):
    """Tests that a series of weights with total != 1 is not accepted"""
    with pytest.raises(ValueError):
        table.sample(table.num_rows, weights=[1/4, 1/4, 1/4, 1/6])

    with pytest.raises(ValueError):
        table.sample(table.num_rows, weights=[1/4, 1/4, 1/4, 1/2])


def test_sample_weights_worepl(table):
    """Tests that with_replacement flag works - ensures with_replacement=False
    works by asserting unique rows for each iteration
    1000: ~3.90s
    2000: ~7.04s
    4000: ~13.2s
    10000: ~33.18s
    """
    iterations, i = 100,  0
    while i < iterations:
        u = table.sample(table.num_rows, with_replacement=False)
        assert len(set(u.rows)) == len(u.rows)
        i += 1


def test_sample_weights_with_none_k(table):
    """Tests that with_replacement flag works - ensures with_replacement=False
    works by asserting unique rows for each iteration, with k=None default
    """
    iterations, i = 100,  0
    while i < iterations:
        u = table.sample(with_replacement=False)
        assert len(set(u.rows)) == len(u.rows)
        i += 1

def test_split_basic(table):
    """Test that table.split works."""
    table.split(3)

def test_split_lengths(table):
    """Test that table.split outputs tables with the right number of rows."""
    sampled, rest = table.split(3)
    assert sampled.num_rows == 3
    assert rest.num_rows == table.num_rows - 3

def test_split_k_vals(table):
    """Test that invalid k values for table.split raises an error."""
    with pytest.raises(ValueError):
        table.split(0)
    with pytest.raises(ValueError):
        table.split(table.num_rows)

#############
# Visualize #
#############

def test_scatter(numbers_table):
    """Tests that Table.scatter doesn't raise an error when the table doesn't
    contains non-numerical values. Not working right now because of TKinter
    issues on Travis.

    TODO(sam): Fix Travis so this runs
    """

    # numbers_table.scatter('count')

def test_scatter_error(table):
    """Tests that Table.scatter raises an error when the table contains
    non-numerical values."""

    with pytest.raises(ValueError):
        table.scatter('letter')

def test_df_roundtrip(table):
    df = table.to_df()
    assert isinstance(df, pd.DataFrame)

    t = Table.from_df(df)

    for (c0, c1) in zip(t.columns, table.columns):
        assert_equal(c0, c1)

def test_array_roundtrip(table):
    arr = table.to_array()
    assert isinstance(arr, np.ndarray)

    t = Table.from_array(arr)
    for (c0, c1) in zip(t.columns, table.columns):
        assert_equal(c0, c1)

    # Now test using the ndarray attribute
    arr = table.values
    assert isinstance(arr, np.ndarray)

    t = Table().with_columns([(nm, vals)
                              for nm, vals in zip(table.labels, arr.T)])
    for (c0, c1) in zip(t.columns, table.columns):
        assert_equal(c0, c1)


def test_url_parse():
    """Test that Tables parses URLs correctly"""
    with pytest.raises(ValueError):
        url = 'https://data8.berkeley.edu/something/something/dark/side'
        Table.read_table(url)