EntityList
The EntityList class extends Python’s built-in list type to provide functional programming methods for filtering, sorting, and mapping operations. All methods return new EntityList instances, allowing for method chaining.
Class Signature
Inherits from Python’s built-in list class, so all standard list methods are available.
Methods
filter()
Filters the list based on a predicate function, returning a new EntityList containing only elements that satisfy the condition.
def filter(self, filter_lambda)
A function that takes a single element and returns True to include it in the result, or False to exclude it.
A new EntityList containing only the elements for which filter_lambda returned True.
Example
from myos import EntityList
# Create an EntityList of numbers
numbers = EntityList([1, 2, 3, 4, 5, 6])
# Filter for even numbers
even_numbers = numbers.filter(lambda x: x % 2 == 0)
print(even_numbers) # [2, 4, 6]
# Filter entities by attribute
users = EntityList([
{"name": "Alice", "age": 30},
{"name": "Bob", "age": 25},
{"name": "Charlie", "age": 35}
])
older_users = users.filter(lambda u: u["age"] > 28)
print(older_users) # [{"name": "Alice", "age": 30}, {"name": "Charlie", "age": 35}]
sort()
Sorts the list based on a key function, returning a new sorted EntityList.
def sort(self, sort_lambda)
A function that takes a single element and returns a value to use for sorting. Elements are sorted based on the return values of this function.
A new EntityList with elements sorted according to the key function.
Example
from myos import EntityList
# Sort numbers in ascending order
numbers = EntityList([5, 2, 8, 1, 9])
sorted_numbers = numbers.sort(lambda x: x)
print(sorted_numbers) # [1, 2, 5, 8, 9]
# Sort in descending order
descending = numbers.sort(lambda x: -x)
print(descending) # [9, 8, 5, 2, 1]
# Sort entities by attribute
users = EntityList([
{"name": "Charlie", "age": 35},
{"name": "Alice", "age": 30},
{"name": "Bob", "age": 25}
])
sorted_by_age = users.sort(lambda u: u["age"])
print([u["name"] for u in sorted_by_age]) # ["Bob", "Alice", "Charlie"]
sorted_by_name = users.sort(lambda u: u["name"])
print([u["name"] for u in sorted_by_name]) # ["Alice", "Bob", "Charlie"]
map()
Transforms each element in the list using a mapping function, returning a new EntityList with the transformed elements.
def map(self, map_lambda)
A function that takes a single element and returns a transformed value.
A new EntityList containing the transformed elements.
Example
from myos import EntityList
# Square all numbers
numbers = EntityList([1, 2, 3, 4, 5])
squared = numbers.map(lambda x: x ** 2)
print(squared) # [1, 4, 9, 16, 25]
# Extract specific attributes
users = EntityList([
{"name": "Alice", "age": 30},
{"name": "Bob", "age": 25},
{"name": "Charlie", "age": 35}
])
names = users.map(lambda u: u["name"])
print(names) # ["Alice", "Bob", "Charlie"]
# Transform data
ages = users.map(lambda u: {"name": u["name"], "senior": u["age"] >= 30})
print(ages)
# [{"name": "Alice", "senior": True}, {"name": "Bob", "senior": False}, {"name": "Charlie", "senior": True}]
Method Chaining
Since all methods return EntityList instances, you can chain operations together:
from myos import EntityList
users = EntityList([
{"name": "Alice", "age": 30, "active": True},
{"name": "Bob", "age": 25, "active": False},
{"name": "Charlie", "age": 35, "active": True},
{"name": "Diana", "age": 28, "active": True}
])
# Chain filter, sort, and map operations
result = (users
.filter(lambda u: u["active"]) # Get active users
.filter(lambda u: u["age"] >= 28) # Age 28 or older
.sort(lambda u: u["age"]) # Sort by age
.map(lambda u: u["name"]) # Extract names
)
print(result) # ["Diana", "Alice", "Charlie"]
Notes
EntityList inherits from Python’s list, so all standard list methods (append(), extend(), pop(), etc.) are available.- The functional methods (
filter(), sort(), map()) do not modify the original list; they return new instances.
- Empty
EntityList instances can be created: empty = EntityList()
- You can initialize from any iterable:
EntityList([1, 2, 3]) or EntityList(range(10))