Searching for matching attributes-CodePudding

My special objects have one list of attribute-values (that is a varying list of abbreviated strings of short but differing length meaning some capabilities of any object) → ['A', 'B', 'AC', 'BC', ...]

running the program I'm searching for at least one existing match out of a varying search-list → ['BC', 'BP', 'X', ...]

At the moment I solved that by iterating over each search-list element using an in-operation against every attribute-list-like:

for e in all_elements:
    for a in valid_attributes:
        if a in e.capabilities:
            handle_match(e, a)

For only a handful of attributes and few elements, it will be endurable in need of time, but...

The further problem: get all a-values at once and handle them in same moment and after that continuing with next e-element.

I thought for a moment about to give each a-value a bit-position inside a big word of currently around 320 bit width and check any occurrence by an and-operation; other idea to use an enumeration for attributes; but my tries hadn't been successful so far.

Does anyone have a better and easier idea? Currently my 1½ year knowledge of Python looks insufficient.

CodePudding user response：

If the attributes are not repeated you can store them as a set instead and calculate the intersection:

for e in all_elements:
    if len(valid_attributes.intersection(e.capabilities))>0:
        handle_match(e, a)

Or at a greater space sacrifice you can store the attribute list as a sparse binary list, where each element represents the existence of some attribute. Then you can check attributes in constant time.

CodePudding user response：

If the attribute string values are unique, you could use sets to quickly determine which ones are value by handling the results of using the set & intersection operator:

class Element:
    def __init__(self, *capabilities):
        self.capabilities = set(capabilities)
    def __repr__(self):
        return f'Element({repr(self.capabilities)})'

VALID_ATTRIBUTES = {'A', 'B', 'AC', 'BC'}

all_elements = [Element('A', 'B'), Element('A', 'AC'), Element(),
                Element('D', 'BC')]

def handle_match(e, a):
    print(f'handle_match({e=!r}, {a=!r})')

for e in all_elements:
    for a in (e.capabilities & VALID_ATTRIBUTES):
        handle_match(e, a)

Results:

handle_match(e=Element({'B', 'A'}), a='B')
handle_match(e=Element({'B', 'A'}), a='A')
handle_match(e=Element({'AC', 'A'}), a='AC')
handle_match(e=Element({'AC', 'A'}), a='A')
handle_match(e=Element({'D', 'BC'}), a='BC')