Python Range Reverse
Python range() function generates a sequence of integers. The sequence could be forward or reverse with respect to the values, when the step is positive or negative respectively.
In Python range() tutorial, we have gone through basic examples of range() function, where we have written Python range() function with positive steps. In this tutorial, we will learn how to take these steps in the backward or negative direction.
Python Range with Negative Steps
If we are taking steps in the backward direction, start argument should be greater than stop to generate any elements in the range object. And step should be a negative number.
In the following example, we shall generate a Python Range with sequence of integers starting from 10, decrementing in steps of 2 until 1.
Python Program
start = 10
stop = 1
step = -2
for i in range(start, stop, step) :
print(i) Try Online Output
10 8 6 4 2
Let us try the same program with different start, stop and step values.
Python Program
start = 100
stop = 0
step = -10
for i in range(start, stop, step) :
print(i) Try Online Output
100 90 80 70 60 50 40 30 20 10
Python Range with Negative Steps & Negative Numbers
In the following example, we shall generate a Python Range with sequence of negative integers starting from -1, decrementing in steps of 3 until -20. Please note that our start is greater than end, and step is negative.
Python Program
start = -1
stop = -20
step = -3
for i in range(start, stop, step) :
print(i) Try Online Output
-1 -4 -7 -10 -13 -16 -19
Conclusion
In this Python Tutorial, we learned how to create a range with sequence of elements starting at a higher value and stopping at a lower value, by taking negative steps.