# Python program to create a list centered on zero

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, -0.5, 0.0, 0.5, 1]`

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