Python | range() method

There are many iterables in Python like list, tuple etc. range() gives another way to initialize a sequence of numbers using some conditions.

range() is commonly used in for looping hence, knowledge of same is key aspect when dealing with any kind of Python code.

Syntax : range(start, stop, step)

Parameters :
start : Element from which sequence constructed has to start. (default:0)
stop : Element number at which numbers in sequence have to end (exclusive).
step : Can be +ve or -ve number, denoting the elements need to be skipped during filling of list. (default:1)

Returns : The list using the formula :
list[n] = start + step*n (for both positive and negative step) where, n >=0 and list[n] = 0 and list[n] > stop (for negative step)

Returns ValueError if step is 0. Value constraint is checked in case of step, failing to meet returns empty sequence, else returns sequence according to formula.



Code #1 : Demonstrating range() without step parameter

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python3 code to demonstrate the 
# working of range() without step
  
# using range()
lis1 = list(range(6))
lis2 = list(range(3, 6))
lis3 = list(range(-6, 2))
  
# initializing list using range, 1 parameter
# only stop parameter
print("List generated using 1 parameter : " + str(lis1)) 
  
# initializing list using range, 2 parameters
# only step and stop parameters
print("List generated using 2 parameters : " + str(lis2)) 
  
# initializing list using range, 2 parameter
# only step and stop parameters
print("List generated using 2 parameters with negatives : " + str(lis3)) 

chevron_right


Output:

List generated using 1 parameter : [0, 1, 2, 3, 4, 5]
List generated using 2 parameters : [3, 4, 5]
List generated using 2 parameters with negatives : [-6, -5, -4, -3, -2, -1, 0, 1]

 

Code #2 : Demonstrating range() using step

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python 3 code to demonstrate the 
# working of range() with step
  
# initializing list using range
# using step
print("List generated using step : " +
    str(list(range(3, 10, 2)))) 
  
# initializing list using range
# using negative step
print("List generated using negative step : " +
                  str(list(range(10, -5, -3))))
  
# initializing list using range
# using negative step,
# value contraints fail case
print("List generated using step, value contraints fail : " +
                                 str(list(range(10, -5, 3))))
  
# initializing list using range
# using 0 step
# error 
print("List generated using 0 step : " +
              str(list(range(3, 7, 0))))

chevron_right


Output:

List generated using step : [3, 5, 7, 9]
List generated using negative step : [10, 7, 4, 1, -2]
List generated using step, value contraints fail : []

Exception:

Traceback (most recent call last):
  File "/home/bdae725dff7b38d3681eee38f6a6d434.py", line 23, in 
    print("List generated using 0 step : " + str(list(range(3, 7, 0))))
ValueError: range() arg 3 must not be zero


My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.