Question

What are Dict and List comprehensions?

Answer 1

Python comprehensions, like decorators, are syntactic sugar constructs that help build altered and filtered lists, dictionaries or sets from a given list, dictionary or set. Using comprehensions, saves a lot of time and code that might be considerably more verbose (containing more lines of code). Let's check out some examples, where comprehensions can be truly beneficial:

• Performing mathematical operations on the entire list

  my_list = [2, 3, 5, 7, 11]
  
  squared_list = [x**2 for x in my_list]    # list comprehension
  # output => [4 , 9 , 25 , 49 , 121]
  
  squared_dict = {x:x**2 for x in my_list}    # dict comprehension
  # output => {11: 121, 2: 4 , 3: 9 , 5: 25 , 7: 49}
  

• Performing conditional filtering operations on the entire list

  my_list = [2, 3, 5, 7, 11]
  
  squared_list = [x**2 for x in my_list <strong style="-webkit-font-smoothing:subpixel-antialiased; border:0px; box-sizing:border-box; font-family:Helvetica,Arial,sans-serif; font-size:15px; font-weight:bold; margin:0px;