Learn List Comprehensions in Python Programming: List Comprehensions is a very powerful tool, which creates a new list based on another list, in a single, readable line. List comprehension is an elegant way to define and create lists based on existing lists. List comprehension is generally more compact and faster than normal functions and loops for creating list. However, we should avoid writing very long list comprehensions in one line to ensure that code is user-friendly.

For example, let’s say we need to create a list of integers which specify the length of each word in a certain sentence, but only if the word is not the word “the”.

sentence = "the quick brown fox jumps over the lazy dog"
words = sentence.split()
word_lengths = []
for word in words:
      if word != "the":
          word_lengths.append(len(word))
print(words)

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Using a list comprehension, we could simplify this process to this notation:

sentence = "the quick brown fox jumps over the lazy dog"
words = sentence.split()
word_lengths = [len(word) for word in words if word != "the"]
print(words)

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Exercise

Using a list comprehension, create a new list called “newlist” out of the list “numbers”, which contains only the positive numbers from the list, as integers.

# this is the answer code. Look below and see if you can complete the exercise on your own.
numbers = [34.6, -203.4, 44.9, 68.3, -12.2, 44.6, 12.7]
newlist = [int(x) for x in numbers if x > 0]
print(newlist)

Learn List Comprehensions in Python Programming

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Exercise

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