Python program to create a list centered on zero

Last Updated : 06 Apr, 2020

Given two integer variables, limit and diff, write a Python program to create a list that is centered on zero, using limit, which specifies limit of the list and diff that specifies the common difference between integers.

Examples:

Input : limit = 1, diff = 0.5
Output : [-1, -0.5, 0.0, 0.5, 1]

Input : limit = 25, diff = 5
Output : [-25, -20, -15, -10, -5, 0, 5, 10, 15, 20, 25]

Approach #1 : Naive Approach

This is a naive approach to the above problem. First, create an empty list ‘lst’, and then we use a while loop to append the next integer with a difference equal to ‘diff’.

# Python3 program to Convert a 
# list to dictionary
  
def create(limit, diff):
          
    lst = [-limit]
    while lst[-1] < limit:
        lst.append(lst[-1] + diff)
    lst[-1] = limit
    return lst
          
# Driver code
limit = 1
diff = 0.5
print(create(limit, diff))

Output:

[-1, -0.5, 0.0, 0.5, 1]

Approach #2 : Using Python Numpy

Using Numpy module makes the solution a lot easier. In this method, we use np.arange which return evenly spaced values within a given interval ‘diff’.

# Python3 program to Convert a 
# list to dictionary
import numpy as np
  
def create(limit, diff):
    lst = np.arange(diff, limit, diff)
    if (lst[-1] != limit):
        lst = np.r_[lst, limit]
          
    return np.r_[-lst[::-1], 0, lst].tolist()
          
# Driver code
limit = 1
diff = 0.5
print(create(limit, diff))

Output:

[-1.0, -0.5, 0.0, 0.5, 1.0]

Approach #3 : list comprehension

# Python3 Python program to create a list centered on zero
  
def create(limit, diff):
    length = int(((limit/diff)*2)+1)    
    list = [-limit+i*diff for i in range(length)]
    return list  
      
          
# Driver code
limit = 1
diff = 0.5
print(create(limit, diff))

Output:

[-1.0, -0.5, 0.0, 0.5, 1.0]

Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course. And to begin with your Machine Learning Journey, join the Machine Learning – Basic Level Course

My Personal Notes

Related Articles

Python program to create a list centered on zero