Lambda Functions

What is the output of the following code?

items = [1, 2, 3, 4, 5]
result = list(map(lambda x: x * 3, items))

A:

[1, 2, 3, 4, 5]

B:

[3, 6, 9, 12, 15]

C:

[1, 4, 9, 16, 25]

D:

[1, 2, 3]

Answer: B

The map() function applies the lambda function to multiply each item by 3.

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What does the following lambda function do?

lambda x: x if x % 2 == 0 else None

A:

Doubles even numbers and returns None for odd numbers.

B:

Filters out even numbers and returns None for odd numbers.

C:

Doubles even numbers and returns the original value for odd numbers.

D:

Returns the square of even numbers and None for odd numbers.

Answer: B

The lambda function filters out even numbers by returning None for them.

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Which built-in function can be used with a lambda function to find the sum of values in an iterable?

A:

sum()

B:

max()

C:

len()

D:

filter()

Answer: A

The sum() function can be used with a lambda function to find the sum of values in an iterable based on the lambda function's criteria.

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When using the sorted() function with a lambda function to sort a list of strings, how can the sorting be case-insensitive?

A:

Use the case_insensitive=True parameter.

B:

Use the lower() method inside the lambda function.

C:

Use the sorted(case_insensitive=True) syntax.

D:

It is not possible to achieve case-insensitive sorting with lambda functions.

Answer: B

Using lower() inside the lambda function converts strings to lowercase, achieving case-insensitive sorting.

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What does the following lambda function accomplish?

lambda x: x.upper()

A:

Converts a string to lowercase.

B:

Converts a string to uppercase.

C:

Reverses a string.

D:

Trims leading and trailing whitespaces from a string.

Answer: B

The lambda function lambda x: x.upper() converts a string to uppercase.

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Questions for: Lambda Functions