DocScoDoc/intervals.py

# -*- mode: python -*-
# -*- coding: utf-8 -*-


# Code from http://code.activestate.com/recipes/457411/

from bisect import bisect_left, bisect_right
from itertools import izip


class intervalmap(object):
    """
        This class maps a set of intervals to a set of values.
        
        >>> i = intervalmap()
        >>> i[0:5] = '0-5'
        >>> i[8:12] = '8-12'
        >>> print i[2]
        0-5
        >>> print i[10]
        8-12
        >>> print repr(i[-1])
        None
        >>> print repr(i[17])
        None
        >>> i[4:9] = '4-9'
        >>> print [(j,i[j]) for j in range(6)]
        [(0, '0-5'), (1, '0-5'), (2, '0-5'), (3, '0-5'), (4, '4-9'), (5, '4-9')]
        >>> print list(i.items())
        [((0, 4), '0-5'), ((4, 9), '4-9'), ((9, 12), '8-12')]
        >>> i[:0] = 'less than 0'
        >>> i[-5]
        'less than 0'
        >>> i[0]
        '0-5'
        >>> print list(i.items())
        [((None, 0), 'less than 0'), ((0, 4), '0-5'), ((4, 9), '4-9'), ((9, 12), '8-12')]
        >>> i[21:] = 'more than twenty'
        >>> i[42]
        'more than twenty'
        >>> i[10.5:15.5] = '10.5-15.5'
        >>> i[11.5]
        '10.5-15.5'
        >>> i[0.5]
        '0-5'
        >>> print list(i.items())
        [((None, 0),... ((9, 10.5), '8-12'), ((10.5, 15.5), '10.5-15.5'), ((21, None),...
        >>> i = intervalmap()
        >>> i[0:2] = 1
        >>> i[2:8] = 2
        >>> i[4:] = 3
        >>> i[5:6] = 4  
        >>> i
        {[0, 2] => 1, [2, 4] => 2, [4, 5] => 3, [5, 6] => 4, [6, None] => 3}
    """

    def __init__(self):
        """
            Initializes an empty intervalmap.
        """
        self._bounds = []
        self._items = []
        self._upperitem = None

    def __setitem__(self, _slice, _value):
        """
            Sets an interval mapping.
        """
        assert isinstance(_slice, slice), "The key must be a slice object"

        if _slice.start is None:
            start_point = -1
        else:
            start_point = bisect_left(self._bounds, _slice.start)

        if _slice.stop is None:
            end_point = -1
        else:
            end_point = bisect_left(self._bounds, _slice.stop)

        if start_point >= 0:
            if (
                start_point < len(self._bounds)
                and self._bounds[start_point] < _slice.start
            ):
                start_point += 1

            if end_point >= 0:
                self._bounds[start_point:end_point] = [_slice.start, _slice.stop]
                if start_point < len(self._items):
                    self._items[start_point:end_point] = [
                        self._items[start_point],
                        _value,
                    ]
                else:
                    self._items[start_point:end_point] = [self._upperitem, _value]
            else:
                self._bounds[start_point:] = [_slice.start]
                if start_point < len(self._items):
                    self._items[start_point:] = [self._items[start_point], _value]
                else:
                    self._items[start_point:] = [self._upperitem]
                self._upperitem = _value
        else:
            if end_point >= 0:
                self._bounds[:end_point] = [_slice.stop]
                self._items[:end_point] = [_value]
            else:
                self._bounds[:] = []
                self._items[:] = []
                self._upperitem = _value

    def __getitem__(self, _point):
        """
            Gets a value from the mapping.
        """
        assert not isinstance(_point, slice), "The key cannot be a slice object"

        index = bisect_right(self._bounds, _point)
        if index < len(self._bounds):
            return self._items[index]
        else:
            return self._upperitem

    def items(self):
        """
            Returns an iterator with each item being
            ((low_bound,high_bound), value). The items are returned
            in order.
        """
        previous_bound = None
        for b, v in izip(self._bounds, self._items):
            if v is not None:
                yield (previous_bound, b), v
            previous_bound = b
        if self._upperitem is not None:
            yield (previous_bound, None), self._upperitem

    def values(self):
        """
            Returns an iterator with each item being a stored value. The items
            are returned in order.
        """
        for v in self._items:
            if v is not None:
                yield v
        if self._upperitem is not None:
            yield self._upperitem

    def __repr__(self):
        s = []
        for b, v in self.items():
            if v is not None:
                s.append("[%r, %r] => %r" % (b[0], b[1], v))
        return "{" + ", ".join(s) + "}"


if __name__ == "__main__":
    # Test 1
    i = intervalmap()
    i[9:] = "!"
    assert repr(i) == "{[9, None] => '!'}"
    i[:5] = "Hello"
    i[6:7] = "World"
    assert repr(i) == "{[None, 5] => 'Hello', [6, 7] => 'World', [9, None] => '!'}"
    i[8:10] = "(Test)"
    assert (
        repr(i)
        == "{[None, 5] => 'Hello', [6, 7] => 'World', [8, 10] => '(Test)', [10, None] => '!'}"
    )
    i[:3] = "My,"
    assert (
        repr(i)
        == "{[None, 3] => 'My,', [3, 5] => 'Hello', [6, 7] => 'World', [8, 10] => '(Test)', [10, None] => '!'}"
    )
    i[5.5:6] = "Cruel"
    assert (
        repr(i)
        == "{[None, 3] => 'My,', [3, 5] => 'Hello', [5.5, 6] => 'Cruel', [6, 7] => 'World', [8, 10] => '(Test)', [10, None] => '!'}"
    )
    i[6:6.5] = "And Harsh"
    assert (
        repr(i)
        == "{[None, 3] => 'My,', [3, 5] => 'Hello', [5.5, 6] => 'Cruel', [6, 6.5] => 'And Harsh', [6.5, 7] => 'World', [8, 10] => '(Test)', [10, None] => '!'}"
    )
    i[5.9:6.6] = None
    assert (
        repr(i)
        == "{[None, 3] => 'My,', [3, 5] => 'Hello', [5.5, 5.9000000000000004] => 'Cruel', [6.5999999999999996, 7] => 'World', [8, 10] => '(Test)', [10, None] => '!'}"
    )
    assert " ".join(i.values()) == "My, Hello Cruel World (Test) !"
    print("Test 1 OK")

    # Test 2
    i = intervalmap()
    i[:0] = "A"
    i[2:5] = "B"
    i[8:10] = "C"
    i[12:] = "D"
    assert (
        repr(i)
        == "{[None, 0] => 'A', [2, 5] => 'B', [8, 10] => 'C', [12, None] => 'D'}"
    )
    i[:] = "K"
    assert repr(i) == "{[None, None] => 'K'}"
    assert i[5] == "K"
    i[0:10] = "L"
    i[6:8] = "M"
    i[20:] = "J"
    assert i[-1] == "K"
    assert i[5] == "L"
    assert i[7] == "M"
    assert i[9] == "L"
    assert i[15] == "K"
    assert i[42] == "J"
    print("Test 2 OK")

    # Test 3
    try:
        from datetime import datetime
    except:
        print("Test 3 skipped")
    else:
        i = intervalmap()
        i[: datetime(2005, 10, 24)] = "A"
        i[datetime(2005, 11, 11) : datetime(2005, 11, 17)] = "B"
        i[datetime(2005, 11, 30) :] = "C"
        assert i[datetime(2005, 9, 25)] == "A"
        assert i[datetime(2005, 10, 23)] == "A"
        assert i[datetime(2005, 10, 26)] == None
        assert i[datetime(2005, 11, 9)] == None
        assert i[datetime(2005, 11, 16)] == "B"
        assert i[datetime(2005, 11, 23)] == None
        assert i[datetime(2005, 11, 29)] == None
        assert i[datetime(2005, 11, 30)] == "C"
        assert i[datetime(2005, 12, 3)] == "C"
        print("Test 3 OK")

    try:
        import doctest
    except:
        print("Skipping the doctests")
    else:
        print("And now, the doctests")
        doctest.testmod(optionflags=doctest.ELLIPSIS)