learn-co-curriculum / dsc-enterprise-bain-list-comprehensions-lab

List Comprehension

Following exercises require to put the skills you've learned in the previous lesson to practice. All exercises simply require you to create a list using list comprehension to address the question. Let's get started.

Exercise 1:

Create a list of all of the numbers from 1-100 that are divisible by 7

# [0, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, 91, 98]

[0, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, 91, 98]

Exercise 2:

Create a list all of the numbers from 1-100 that have a 9 in them

# [9, 19, 29, 39, 49, 59, 69, 79, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99]

[9, 19, 29, 39, 49, 59, 69, 79, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99]

Exercise 3:

Remove all the wovels and spaces from the string "A quick brown fox jumped over the lazy dog". Output a list with only letters from the string - minus the vowels and spaces, as shown the comments.

# Use this string in your list comprehension
string = "A quick brown fox jumped over the lazy dog"

# ['q',
#  'c',
#  'k',
#  'b',
#  'r',
#  'w',
#  'n',
#  'f',
#  'x',
#  'j',
#  'm',
#  'p',
#  'd',
#  'v',
#  'r',
#  't',
#  'h',
#  'l',
#  'z',
#  'y',
#  'd',
#  'g']

['q',
 'c',
 'k',
 'b',
 'r',
 'w',
 'n',
 'f',
 'x',
 'j',
 'm',
 'p',
 'd',
 'v',
 'r',
 't',
 'h',
 'l',
 'z',
 'y',
 'd',
 'g']

Exercise 4:

Find all of the words in a string that have less than 4 letters. Use the string "A quick brown fox jumped over the lazy dog" as before.

string = "A quick brown fox jumped over the lazy dog"

# ['A', 'fox', 'the', 'dog']

['A', 'fox', 'the', 'dog']

Exercise 5:

Use a nested list comprehension to find all of the numbers from 1-25 that are divisible by any single digit besides 1 (2-9)

# [2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25]

[2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25]

Conclusion

So now you have a good understanding of how to write list comprehensions in different situations. IN certain situations, such list comprehensions can be used to replace (nested) for loops or lambda functions with map(), filter() and reduce(). You are encouraged to implement these in your coding practice as these would produce a neat looking code that is more efficient and easy to troubleshoot.