Python – Lambda Expressions – With YouTube Video

As one of the acknoledged reviewers of the Manning book Python How-To, I have decided to make a YouTube video, based on a part of the book, mentioning Lambda Expressions.

The video is here, and the code I have used is pretty much this one:

a = lambda x: x * 2
print(a(3))

#syntax error if you use RETURN keyword:
a = lambda x: return x * 2
print(a(3))

tasks = [
    {'title': 'A', 'desc': 'First Letter', 'urgency': 6},
    {'title': 'B', 'desc': 'Second Letter', 'urgency': 5},
    {'title': 'C', 'desc': 'Third Letter', 'urgency': 2}
]

def using_urgency_level(task):
    return task['urgency']

tasks.sort(key=using_urgency_level, reverse=True)
print(tasks)

def using_urgency_level(task):
    return task['urgency']

tasks.sort(key=lambda x: x['urgency'], reverse=False)
print(tasks)

using_urgency_level = lambda x: x['urgency']
tasks.sort(key=using_urgency_level, reverse=True)
print(tasks)

integers = [-4, 3, 7, 0, -6]
sorted_abs = sorted(integers, key=lambda x: abs(x))
print(sorted_abs)
print(integers)

#pythonic way:
integers = [-4, 3, 7, 0, -6]
sorted_abs = sorted(integers, key=abs)
print(sorted_abs)
print(integers)

scores = [(1, 2, 3), (4, 4, 5), (2, 3, 4), (1, 2, 7)]
max(scores, key=lambda x: x[0] + x[1] + x[2])
max(scores, key=sum)

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