Question

How to write custom callback function to a list (apply a function to each element) in Python

Answer 1

# Using a custom “map” function (classic callback style)

# Custom function that applies a callback to each element
def apply_to_list(lst, callback):
    result = []
    for item in lst:
        result.append(callback(item))   # apply the callback
    return result

# callback function: double the number
def double(x):
    return x * 2

numbers = [5, 10, 15, 20]

doubled = apply_to_list(numbers, double)

print(doubled)



'''
run:

[10, 20, 30, 40]

'''

 

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