map() for element-wise mapping in Data Analysis Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to apply the function str.upper to each element in the list words using map().

Data Analysis Python

words = ['apple', 'banana', 'cherry']
result = list(map([1], words))
print(result)

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Aupper

Blambda x: x.lower()

Cstr.upper()

Dstr.upper

Attempts:

3 left

💡 Hint

Common Mistakes

Using str.upper() instead of str.upper.

Passing a string like 'upper' instead of the function.

The map() function requires a function object as the first argument. str.upper is the method reference, while str.upper() calls the method immediately, which is incorrect here.

2fill in blank

medium

Complete the code to convert all numbers in the list nums to strings using map().

Data Analysis Python

nums = [1, 2, 3, 4]
str_nums = list(map([1], nums))
print(str_nums)

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Astr

Bfloat

Cint

Dlambda x: x + 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using int which does not convert numbers to strings.

Using a lambda that adds 1 instead of converting to string.

The str function converts numbers to strings, which is what we want to apply to each element.

3fill in blank

hard

Fix the error in the code to correctly apply the function abs to each element in the list values using map().

Data Analysis Python

values = [-1, -2, 3]
result = list(map([1], values))
print(result)

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Aabs()

Babs

Clambda x: abs(x)

Dabs(x)

Attempts:

3 left

💡 Hint

Common Mistakes

Using abs() which calls the function immediately.

Trying to use abs(x) directly without a lambda.

The map() function needs a function object, so abs without parentheses is correct. abs() calls the function immediately and is incorrect here.

4fill in blank

hard

Fill both blanks to create a list of squares of numbers greater than 3 using map() and filter().

Data Analysis Python

numbers = [1, 2, 3, 4, 5]
filtered = filter([1], numbers)
squares = list(map([2], filtered))
print(squares)

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Alambda x: x > 3

Blambda x: x < 3

Clambda x: x**2

Dlambda x: x*2

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong filter condition like x < 3.

Using map function that doubles instead of squares.

The filter() uses a function that returns True for numbers greater than 3. The map() applies the square function to each filtered number.

5fill in blank

hard

Fill all three blanks to create a dictionary mapping each word to its length, but only for words longer than 4 characters, using filter() and dictionary comprehension.

Data Analysis Python

words = ['apple', 'bat', 'carrot', 'dog']
lengths = { [1]: [2] for [3] in filter(lambda word: len(word) > 4, words) }
print(lengths)

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Aword

Blen(word)

Dw

Attempts:

3 left

💡 Hint

Common Mistakes

Using inconsistent variable names between filter and comprehension.

Using wrong expressions for keys or values.

The dictionary comprehension uses word as the variable from the filter. The key is the word itself, and the value is its length.