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relationalai.std.math.factorial()

factorial(number: Number|Producer) -> Expression

Calculates the factorial of number. Only defined for integer values between 0 and 33, inclusive. If number is a Producer, factorial() filters out any invalid values from the producer. Must be called in a rule or query context.

Parameters

Name	Type	Description
`number`	`Producer` or Python `Number` object	The non-negative integer to calculate the factorial of.

Returns

An Expression object.

Example

Use factorial() to calculate the factorial of a number:

import relationalai as rai
from relationalai.std import math


# =====
# SETUP
# =====

model = rai.Model("MyModel")
Person = model.Type("Person")

with model.rule():
    Person.add(id=1).set(name="Alice", age=20)
    Person.add(id=2).set(name="Bob", age=-1)  # Negative age
    Person.add(id=3).set(name="Carol", age="30")  # Non-integer age


# =======
# EXAMPLE
# =======

# Set an age_factorial property to the factorial of each person's age.
with model.rule():
    person = Person()
    person.set(age_factorial=math.factorial(person.age))

# Since factorial() filters out non-integer and negative values, the age_factorial
# property is not set for Bob or Carol.
with model.query() as select:
    person = Person()
    response = select(person.id, person.name, person.age_factorial)

print(response.results)
#    id   name  age_factorial
# 0   1  Alice   2.432902e+18
# 1   2    Bob            NaN
# 2   3  Carol            NaN

Note that factorial() only accepts input values less than or equal to 33. Integer values greater than 33 are filtered out:

# Add a person with age=34
with model.rule():
    Person.add(id=4).set(name="Derek", age=34)

# Since 34 is greater than 33, the age_factorial property is not set for Derek.
with model.query() as select:
    person = Person()
    response = select(person.id, person.name, person.age_factorial)

print(response.results)
#    id   name  age_factorial
# 0   1  Alice   2.432902e+18
# 1   2    Bob            NaN
# 2   3  Carol            NaN
# 3   4  Derek            NaN

See Also