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PETsARD YAML
Constrainer YAML
Field Constraints

Field Constraints

Define value domain constraints for individual fields using string expressions.

Usage Examples

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field_constraints:
  - "age >= 18 & age <= 65"                                 # Age range: 18-65 years
  - "hours-per-week >= 20 & hours-per-week <= 60"           # Working hours: 20-60 hours per week
  - "income == '<=50K' | (age > 50 & hours-per-week < 40)"  # Low income or elderly with reduced hours
  - "native-country IS NOT 'United-States'"                 # Non-US nationality
  - "occupation IS pd.NA"                                   # Missing occupation information
  - "education == 'Doctorate' & income == '>50K'"           # Doctorate degree must have high income
  - "(race != 'White') == (income == '>50K')"               # Mutual exclusivity check between non-White race and high income
  - "(marital-status == 'Married-civ-spouse' & hours-per-week > 40) | (marital-status == 'Never-married' & age < 30)" # Complex logical combination

Syntax Format

Comparison Operators 

- "field_name > value"   # Greater than (numeric)
- "field_name >= value"  # Greater than or equal to (numeric)
- "field_name == value"  # Equal to (numeric, text)
- "field_name != value"  # Not equal to (numeric, text)
- "field_name < value"   # Less than (numeric)
- "field_name <= value"  # Less than or equal to (numeric)

Logical Operators 

- "field_name > value1 & field_name < value2"        # AND
- "field_name == 'value1' | field_name == 'value2'"  # OR
- "(condition1 & condition2) | condition3"           # Parentheses for precedence

Null Value Checking 

- "field_name IS pd.NA"      # Field is null
- "field_name IS NOT pd.NA"  # Field is not null

Date Comparison 

- "date_field >= DATE('2020-01-01')"  # Date greater than or equal to 2020-01-01

Operator Precedence

PriorityOperatorDescription
1 (Highest)()Parentheses
2>, >=, ==, !=, <, <=, IS, IS NOTComparison operators
3&Logical AND
4 (Lowest)|Logical OR

Note: Comparison operators have higher precedence than logical operators (AND, OR). This means age >= 20 & age <= 60 is correctly parsed as (age >= 20) & (age <= 60).

Recommendation: Use parentheses to explicitly specify precedence and avoid ambiguity.

Important Notes

  • Each constraint must be wrapped as a string with quotes
  • String values must be single-quoted: "field == 'value'"
    • The outer double quotes wrap the entire constraint expression
    • The inner single quotes denote string literal values (e.g., '<=50K', '>50K')
    • String literals are correctly parsed even when they contain operators like <= or >
    • Examples: "income == '<=50K'", "status == '>active'", "country == 'United-States'"
  • Use IS or IS NOT for null checking, not == or !=
  • Does not support cross-field operations (e.g., field1 + field2 > 100)
NaN HandlingField Combinations