Get started learning Python with DataCamp's free Intro to Python tutorial. Learn Data Science by completing interactive coding challenges and watching videos by expert instructors. Start Now!

Previous Tutorial Next Tutorial

List Comprehensions


List Comprehensions is a very powerful tool, which creates a new list based on another list, in a single, readable line.

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)

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)

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.

numbers = [34.6, -203.4, 44.9, 68.3, -12.2, 44.6, 12.7] newlist = [] print(newlist) 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) test_output_contains("[34, 44, 68, 44, 12]") success_msg("Very nice!")

This site generously supported by DataCamp. DataCamp offers online interactive Python Tutorials for Data Science. Join over a million other learners and get started learning Python for data science today!

Previous Tutorial Next Tutorial