How do you set a range in Python?

You set a range in Python using the built-in range() function. This function generates a sequence of numbers, which can be very useful for loops and other iterative tasks. The range() function is quite flexible, allowing you to customize the starting point, ending point, and step size of your number sequence.

Understanding the range() Function

The range() function has three parameters: start, stop, and step.

Parameter	Description	Default Value
start	The beginning number of the sequence.	0
stop	The number where the sequence ends (exclusive).	Required
step	The increment between numbers in the sequence.	1

• range(stop): When you provide a single argument, stop, the sequence starts at 0, increments by 1, and stops before reaching the stop value.

  for i in range(5): # Generates 0, 1, 2, 3, 4
      print(i)

• range(start, stop): When you provide two arguments, start and stop, the sequence starts at start, increments by 1, and stops before reaching the stop value.

  for i in range(2, 7): # Generates 2, 3, 4, 5, 6
      print(i)

• range(start, stop, step): When you provide three arguments, start, stop, and step, the sequence starts at start, increments by step, and stops before reaching the stop value.

  for i in range(1, 10, 2): # Generates 1, 3, 5, 7, 9
      print(i)

Practical Applications and Insights

• The stop value is always exclusive, meaning the generated sequence does not include it.
• The step value can be negative, allowing for sequences that count down. For example, range(5, 0, -1) will generate 5, 4, 3, 2, 1.
• The range() function does not generate a list; instead, it generates a sequence of numbers on demand, saving memory, especially for very large ranges. To create a list, use list(range(start, stop, step)).
• The range() function is extremely helpful in conjunction with for loops for iterating a specific number of times or over a sequence of numbers.

Examples:

• Generate a list of even numbers between 10 and 20:

   even_numbers = list(range(10, 21, 2))
   print(even_numbers) # Output: [10, 12, 14, 16, 18, 20]

• Generate a countdown sequence from 5 to 1:

   for i in range(5, 0, -1):
      print(i) #Output: 5, 4, 3, 2, 1

• Generate a range of numbers from -3 to 3:

   numbers = list(range(-3,4))
   print(numbers) # Output: [-3, -2, -1, 0, 1, 2, 3]