Skip to content

Composition pattern

Composition pattern parsing and manipulation for households.

This module handles household composition patterns like ">=2 >=0 2 0" which specify the required number of people in each age category.

CompositionPattern dataclass

Represents a household composition pattern.

Example: ">=2 >=0 2 <=2" means: - 2 or more people in category 0 (Kids) - 0 or more people in category 1 (Young Adults) - exactly 2 people in category 2 (Adults) - 2 or fewer people in category 3 (Old Adults)

Source code in may/residence/composition_pattern.py 
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
@dataclass
class CompositionPattern:
    """
    Represents a household composition pattern.

    Example: ">=2 >=0 2 <=2" means:
    - 2 or more people in category 0 (Kids)
    - 0 or more people in category 1 (Young Adults)
    - exactly 2 people in category 2 (Adults)
    - 2 or fewer people in category 3 (Old Adults)
    """
    original_pattern: str
    requirements: List[Tuple[str, int]]  # List of (operator, count) for each category
    # operator can be "exact", "gte" (>=), or "lte" (<=)

    # Object cache for CompositionPattern instances
    _instance_cache = {}

    @classmethod
    def from_string(cls, pattern: str) -> 'CompositionPattern':
        """
        Parse a composition pattern string (with object-level caching).

        Args:
            pattern: Pattern string like ">=2 >=0 2 <=2"

        Returns:
            CompositionPattern object
        """
        pattern = pattern.strip()
        if pattern in cls._instance_cache:
            return cls._instance_cache[pattern]

        # Use cached parsing function for internal requirements
        requirements_tuple = _parse_pattern_cached(pattern)
        instance = cls(original_pattern=pattern, requirements=list(requirements_tuple))

        # Cache the instance
        cls._instance_cache[pattern] = instance
        return instance

    def __post_init__(self):
        """Initialize cached properties."""
        self._string_repr = None
        self._min_size = None

    def get_min_count(self, category_idx: int) -> int:
        """Get minimum required count for a category."""
        if category_idx >= len(self.requirements):
            return 0
        operator, count = self.requirements[category_idx]
        if operator == "lte":
            return 0  # <=N means minimum is 0
        return count  # For "exact" and "gte", minimum is the count

    def get_max_count(self, category_idx: int) -> Optional[int]:
        """Get maximum allowed count for a category (None if unlimited)."""
        if category_idx >= len(self.requirements):
            return None
        operator, count = self.requirements[category_idx]
        if operator == "exact":
            return count  # Exact N means max is N
        elif operator == "lte":
            return count  # <=N means max is N
        else:  # gte
            return None  # >=N means no upper limit

    def is_flexible(self, category_idx: int) -> bool:
        """Check if a category has flexible (>= or <=) requirement."""
        if category_idx >= len(self.requirements):
            return True
        operator, _ = self.requirements[category_idx]
        return operator in ("gte", "lte")

    def min_household_size(self) -> int:
        """Calculate minimum household size required (with caching)."""
        if self._min_size is None:
            self._min_size = sum(self.get_min_count(i) for i in range(len(self.requirements)))
        return self._min_size

    def validate_against_rules(self, validation_rules: List[Dict],
                              category_name_to_idx: Dict[str, int]) -> bool:
        """
        Validate this pattern against a list of validation rules.

        Args:
            validation_rules: List of rule dicts from config
            category_name_to_idx: Mapping from category name to index

        Returns:
            bool: True if pattern passes all rules, False otherwise
        """
        for rule in validation_rules:
            # Extract rule components
            condition = rule.get('condition', {})
            requirement = rule.get('requirement', {})
            rule_name = rule.get('name', 'Unnamed rule')

            # Get category indices
            cond_category = condition.get('category')
            if cond_category not in category_name_to_idx:
                logger.warning(f"Rule '{rule_name}': Unknown category '{cond_category}'")
                continue

            cond_cat_idx = category_name_to_idx[cond_category]
            cond_count = self.get_min_count(cond_cat_idx)

            # Evaluate condition
            cond_operator = condition.get('operator')
            cond_value = condition.get('value')
            if not self._evaluate_operator(cond_count, cond_operator, cond_value):
                continue # Condition not met, skip to next rule

            # Condition met, check requirement(s)
            # requirement can be a single dict or a list of dicts (OR condition)
            req_list = requirement if isinstance(requirement, list) else [requirement]

            any_req_met = False
            for req in req_list:
                req_category = req.get('category')
                if req_category not in category_name_to_idx:
                    logger.warning(f"Rule '{rule_name}': Unknown category '{req_category}'")
                    continue

                req_cat_idx = category_name_to_idx[req_category]
                req_count = self.get_min_count(req_cat_idx)

                req_operator = req.get('operator')
                req_value = req.get('value')

                if self._evaluate_operator(req_count, req_operator, req_value):
                    any_req_met = True
                    break

            if not any_req_met:
                if logger.isEnabledFor(logging.DEBUG):
                    logger.debug(f"  Pattern violates rule '{rule_name}': {self}")
                return False

        return True

    def _evaluate_operator(self, actual: int, operator: str, expected: int) -> bool:
        """
        Evaluate a comparison operator.

        Args:
            actual: Actual value
            operator: Comparison operator (>=, >, ==, <=, <)
            expected: Expected value

        Returns:
            bool: True if comparison holds, False otherwise
        """
        if operator == ">=":
            return actual >= expected
        elif operator == ">":
            return actual > expected
        elif operator == "==":
            return actual == expected
        elif operator == "<=":
            return actual <= expected
        elif operator == "<":
            return actual < expected
        else:
            logger.warning(f"Unknown operator '{operator}', assuming False")
            return False

    def demote_once(self, priority_order: List[int]) -> Optional['CompositionPattern']:
        """
        Attempt to demote this pattern by reducing requirements.

        Args:
            priority_order: List of category indices in order of demotion priority

        Returns:
            New CompositionPattern with reduced requirements, or None if can't demote
        """
        new_requirements = list(self.requirements)

        # Try to demote in priority order
        for cat_idx in priority_order:
            if cat_idx >= len(new_requirements):
                continue

            operator, count = new_requirements[cat_idx]

            # Try to reduce the count
            if operator == "gte" and count > 0:
                # Reduce >=N to >=(N-1)
                new_requirements[cat_idx] = ("gte", count - 1)
                return CompositionPattern(
                    original_pattern=self.original_pattern,
                    requirements=new_requirements
                )
            elif operator == "exact" and count > 0:
                # Reduce exact N to (N-1)
                new_requirements[cat_idx] = ("exact", count - 1)
                return CompositionPattern(
                    original_pattern=self.original_pattern,
                    requirements=new_requirements
                )

        # Couldn't demote further
        return None

    def demote_to_count(self, cat_idx: int, target_count: int) -> Optional['CompositionPattern']:
        """
        Demote a specific category directly to a target count.

        This is more efficient than calling demote_once multiple times,
        as it jumps directly to the available count.

        Args:
            cat_idx: Category index to demote
            target_count: Target count to demote to (usually the available count)

        Returns:
            New CompositionPattern with the category set to >=target_count, or None if can't demote
        """
        if cat_idx >= len(self.requirements):
            return None

        operator, current_count = self.requirements[cat_idx]

        # Only demote if target is less than current
        # For "gte" operator, demote to >=target_count
        # For "exact" operator, demote to target_count (exact)
        if operator == "gte" and target_count < current_count:
            new_requirements = list(self.requirements)
            new_requirements[cat_idx] = ("gte", target_count)
            return CompositionPattern(
                original_pattern=self.original_pattern,
                requirements=new_requirements
            )
        elif operator == "exact" and target_count < current_count:
            new_requirements = list(self.requirements)
            new_requirements[cat_idx] = ("exact", target_count)
            return CompositionPattern(
                original_pattern=self.original_pattern,
                requirements=new_requirements
            )

        # No demotion needed or possible
        return None

    def promote_once(self, priority_order: List[int]) -> Optional['CompositionPattern']:
        """
        Attempt to promote this pattern by relaxing requirements to allow more people.

        Promotion converts:
          - "0" (exact) -> ">=0" (flexible, allow any)
          - "N" (exact) -> ">=N" (flexible, allow N or more)

        Args:
            priority_order: List of category indices in order of promotion priority

        Returns:
            New CompositionPattern with relaxed requirements, or None if can't promote
        """
        new_requirements = list(self.requirements)

        # Try to promote in priority order
        for cat_idx in priority_order:
            if cat_idx >= len(new_requirements):
                continue

            operator, count = new_requirements[cat_idx]

            # Only promote exact counts (not already flexible)
            if operator == "exact":
                # Convert exact count to >=count
                new_requirements[cat_idx] = ("gte", count)
                return CompositionPattern(
                    original_pattern=self.original_pattern,
                    requirements=new_requirements
                )

        # Couldn't promote further (all categories already flexible)
        return None

    def _requirements_to_string(self, requirements: List[Tuple[str, int]]) -> str:
        """Convert requirements back to pattern string."""
        parts = []
        for operator, count in requirements:
            if operator == "gte":
                parts.append(f">={count}")
            elif operator == "lte":
                parts.append(f"<={count}")
            else:  # exact
                parts.append(str(count))
        return " ".join(parts)

    def __repr__(self):
        return f"Pattern({self.to_string()})"

    def to_string(self) -> str:
        """Get current pattern as string (with lazy caching)."""
        if self._string_repr is None:
            self._string_repr = self._requirements_to_string(self.requirements)
        return self._string_repr

__post_init__()

Initialize cached properties.

Source code in may/residence/composition_pattern.py 
81
82
83
84
def __post_init__(self):
    """Initialize cached properties."""
    self._string_repr = None
    self._min_size = None

demote_once(priority_order)

Attempt to demote this pattern by reducing requirements.

Parameters:

Name Type Description Default
priority_order List[int]

List of category indices in order of demotion priority

 required

Returns:

Type Description
Optional[CompositionPattern]

New CompositionPattern with reduced requirements, or None if can't demote
Source code in may/residence/composition_pattern.py 
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
def demote_once(self, priority_order: List[int]) -> Optional['CompositionPattern']:
    """
    Attempt to demote this pattern by reducing requirements.

    Args:
        priority_order: List of category indices in order of demotion priority

    Returns:
        New CompositionPattern with reduced requirements, or None if can't demote
    """
    new_requirements = list(self.requirements)

    # Try to demote in priority order
    for cat_idx in priority_order:
        if cat_idx >= len(new_requirements):
            continue

        operator, count = new_requirements[cat_idx]

        # Try to reduce the count
        if operator == "gte" and count > 0:
            # Reduce >=N to >=(N-1)
            new_requirements[cat_idx] = ("gte", count - 1)
            return CompositionPattern(
                original_pattern=self.original_pattern,
                requirements=new_requirements
            )
        elif operator == "exact" and count > 0:
            # Reduce exact N to (N-1)
            new_requirements[cat_idx] = ("exact", count - 1)
            return CompositionPattern(
                original_pattern=self.original_pattern,
                requirements=new_requirements
            )

    # Couldn't demote further
    return None

demote_to_count(cat_idx, target_count)

Demote a specific category directly to a target count.

This is more efficient than calling demote_once multiple times, as it jumps directly to the available count.

Parameters:

Name Type Description Default
cat_idx int

Category index to demote

 required
target_count int

Target count to demote to (usually the available count)

 required

Returns:

Type Description
Optional[CompositionPattern]

New CompositionPattern with the category set to >=target_count, or None if can't demote
Source code in may/residence/composition_pattern.py 
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
def demote_to_count(self, cat_idx: int, target_count: int) -> Optional['CompositionPattern']:
    """
    Demote a specific category directly to a target count.

    This is more efficient than calling demote_once multiple times,
    as it jumps directly to the available count.

    Args:
        cat_idx: Category index to demote
        target_count: Target count to demote to (usually the available count)

    Returns:
        New CompositionPattern with the category set to >=target_count, or None if can't demote
    """
    if cat_idx >= len(self.requirements):
        return None

    operator, current_count = self.requirements[cat_idx]

    # Only demote if target is less than current
    # For "gte" operator, demote to >=target_count
    # For "exact" operator, demote to target_count (exact)
    if operator == "gte" and target_count < current_count:
        new_requirements = list(self.requirements)
        new_requirements[cat_idx] = ("gte", target_count)
        return CompositionPattern(
            original_pattern=self.original_pattern,
            requirements=new_requirements
        )
    elif operator == "exact" and target_count < current_count:
        new_requirements = list(self.requirements)
        new_requirements[cat_idx] = ("exact", target_count)
        return CompositionPattern(
            original_pattern=self.original_pattern,
            requirements=new_requirements
        )

    # No demotion needed or possible
    return None

from_string(pattern) classmethod

Parse a composition pattern string (with object-level caching).

Parameters:

Name Type Description Default
pattern str

Pattern string like ">=2 >=0 2 <=2"

 required

Returns:

Type Description
CompositionPattern

CompositionPattern object
Source code in may/residence/composition_pattern.py 
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
@classmethod
def from_string(cls, pattern: str) -> 'CompositionPattern':
    """
    Parse a composition pattern string (with object-level caching).

    Args:
        pattern: Pattern string like ">=2 >=0 2 <=2"

    Returns:
        CompositionPattern object
    """
    pattern = pattern.strip()
    if pattern in cls._instance_cache:
        return cls._instance_cache[pattern]

    # Use cached parsing function for internal requirements
    requirements_tuple = _parse_pattern_cached(pattern)
    instance = cls(original_pattern=pattern, requirements=list(requirements_tuple))

    # Cache the instance
    cls._instance_cache[pattern] = instance
    return instance

get_max_count(category_idx)

Get maximum allowed count for a category (None if unlimited).

Source code in may/residence/composition_pattern.py 
 95
 96
 97
 98
 99
100
101
102
103
104
105
def get_max_count(self, category_idx: int) -> Optional[int]:
    """Get maximum allowed count for a category (None if unlimited)."""
    if category_idx >= len(self.requirements):
        return None
    operator, count = self.requirements[category_idx]
    if operator == "exact":
        return count  # Exact N means max is N
    elif operator == "lte":
        return count  # <=N means max is N
    else:  # gte
        return None  # >=N means no upper limit

get_min_count(category_idx)

Get minimum required count for a category.

Source code in may/residence/composition_pattern.py 
86
87
88
89
90
91
92
93
def get_min_count(self, category_idx: int) -> int:
    """Get minimum required count for a category."""
    if category_idx >= len(self.requirements):
        return 0
    operator, count = self.requirements[category_idx]
    if operator == "lte":
        return 0  # <=N means minimum is 0
    return count  # For "exact" and "gte", minimum is the count

is_flexible(category_idx)

Check if a category has flexible (>= or <=) requirement.

Source code in may/residence/composition_pattern.py 
107
108
109
110
111
112
def is_flexible(self, category_idx: int) -> bool:
    """Check if a category has flexible (>= or <=) requirement."""
    if category_idx >= len(self.requirements):
        return True
    operator, _ = self.requirements[category_idx]
    return operator in ("gte", "lte")

min_household_size()

Calculate minimum household size required (with caching).

Source code in may/residence/composition_pattern.py 
114
115
116
117
118
def min_household_size(self) -> int:
    """Calculate minimum household size required (with caching)."""
    if self._min_size is None:
        self._min_size = sum(self.get_min_count(i) for i in range(len(self.requirements)))
    return self._min_size

promote_once(priority_order)

Attempt to promote this pattern by relaxing requirements to allow more people.

Promotion converts
  • "0" (exact) -> ">=0" (flexible, allow any)
  • "N" (exact) -> ">=N" (flexible, allow N or more)

Parameters:

Name Type Description Default
priority_order List[int]

List of category indices in order of promotion priority

 required

Returns:

Type Description
Optional[CompositionPattern]

New CompositionPattern with relaxed requirements, or None if can't promote
Source code in may/residence/composition_pattern.py 
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
def promote_once(self, priority_order: List[int]) -> Optional['CompositionPattern']:
    """
    Attempt to promote this pattern by relaxing requirements to allow more people.

    Promotion converts:
      - "0" (exact) -> ">=0" (flexible, allow any)
      - "N" (exact) -> ">=N" (flexible, allow N or more)

    Args:
        priority_order: List of category indices in order of promotion priority

    Returns:
        New CompositionPattern with relaxed requirements, or None if can't promote
    """
    new_requirements = list(self.requirements)

    # Try to promote in priority order
    for cat_idx in priority_order:
        if cat_idx >= len(new_requirements):
            continue

        operator, count = new_requirements[cat_idx]

        # Only promote exact counts (not already flexible)
        if operator == "exact":
            # Convert exact count to >=count
            new_requirements[cat_idx] = ("gte", count)
            return CompositionPattern(
                original_pattern=self.original_pattern,
                requirements=new_requirements
            )

    # Couldn't promote further (all categories already flexible)
    return None

to_string()

Get current pattern as string (with lazy caching).

Source code in may/residence/composition_pattern.py 
335
336
337
338
339
def to_string(self) -> str:
    """Get current pattern as string (with lazy caching)."""
    if self._string_repr is None:
        self._string_repr = self._requirements_to_string(self.requirements)
    return self._string_repr

validate_against_rules(validation_rules, category_name_to_idx)

Validate this pattern against a list of validation rules.

Parameters:

Name Type Description Default
validation_rules List[Dict]

List of rule dicts from config

 required
category_name_to_idx Dict[str, int]

Mapping from category name to index

 required

Returns:

Name Type Description
bool bool

True if pattern passes all rules, False otherwise
Source code in may/residence/composition_pattern.py 
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
def validate_against_rules(self, validation_rules: List[Dict],
                          category_name_to_idx: Dict[str, int]) -> bool:
    """
    Validate this pattern against a list of validation rules.

    Args:
        validation_rules: List of rule dicts from config
        category_name_to_idx: Mapping from category name to index

    Returns:
        bool: True if pattern passes all rules, False otherwise
    """
    for rule in validation_rules:
        # Extract rule components
        condition = rule.get('condition', {})
        requirement = rule.get('requirement', {})
        rule_name = rule.get('name', 'Unnamed rule')

        # Get category indices
        cond_category = condition.get('category')
        if cond_category not in category_name_to_idx:
            logger.warning(f"Rule '{rule_name}': Unknown category '{cond_category}'")
            continue

        cond_cat_idx = category_name_to_idx[cond_category]
        cond_count = self.get_min_count(cond_cat_idx)

        # Evaluate condition
        cond_operator = condition.get('operator')
        cond_value = condition.get('value')
        if not self._evaluate_operator(cond_count, cond_operator, cond_value):
            continue # Condition not met, skip to next rule

        # Condition met, check requirement(s)
        # requirement can be a single dict or a list of dicts (OR condition)
        req_list = requirement if isinstance(requirement, list) else [requirement]

        any_req_met = False
        for req in req_list:
            req_category = req.get('category')
            if req_category not in category_name_to_idx:
                logger.warning(f"Rule '{rule_name}': Unknown category '{req_category}'")
                continue

            req_cat_idx = category_name_to_idx[req_category]
            req_count = self.get_min_count(req_cat_idx)

            req_operator = req.get('operator')
            req_value = req.get('value')

            if self._evaluate_operator(req_count, req_operator, req_value):
                any_req_met = True
                break

        if not any_req_met:
            if logger.isEnabledFor(logging.DEBUG):
                logger.debug(f"  Pattern violates rule '{rule_name}': {self}")
            return False

    return True