[concept]Functions & Apply
Lambda Functions
# theory
lambdas
A lambda is a small, anonymous function. Instead of using def:
def double(x):
return x * 2You can write:
double = lambda x: x * 2syntax
lambda arguments: expression- No
defkeyword - No function name (anonymous)
- Single expression (no statements)
- Implicit return
examples
# One argument
square = lambda x: x ** 2
print(square(5)) # 25
# Multiple arguments
add = lambda a, b: a + b
print(add(3, 4)) # 7
# With conditional
grade = lambda score: "Pass" if score >= 70 else "Fail"
print(grade(85)) # "Pass"with map() and filter()
numbers = [1, 2, 3, 4, 5]
# map: apply function to each element
doubled = list(map(lambda x: x * 2, numbers))
# [2, 4, 6, 8, 10]
# filter: keep elements where function returns True
evens = list(filter(lambda x: x % 2 == 0, numbers))
# [2, 4]# examples [3]
# example 01 · lambda with map()
Transform each element in a list
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# example 02 · lambda with filter()
Keep only elements meeting a condition
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# example 03 · lambda for sorting
Custom sort keys with lambda
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# challenges [2]
# challenge 01/02todo
Use map() with a lambda to convert ['hello', 'world'] to uppercase. Print the result.
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# challenge 02/02todo
Use filter() with a lambda to keep only strings longer than 3 chars from ['hi', 'hello', 'bye', 'goodbye'].
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# project
# project-challenge
thread: Sales Performance Dashboard · reward: 50 xp
# brief
The dashboard needs a quick revenue calculation for each sale. Use a lambda function to calculate Quantity times UnitPrice for all sales records.
# task
Calculate Revenue with Lambda
# your code
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