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Python | Create list of numbers with given range
• Difficulty Level : Basic
• Last Updated : 20 Nov, 2019

Given two numbers r1 and r2 (which defines the range), write a Python program to create a list with the given range (inclusive).

Examples:

```Input : r1 = -1, r2 = 1
Output : [-1, 0, 1]

Input : r1 = 5, r2 = 9
Output : [5, 6, 7, 8, 9]
```

Let’s discuss a few approaches to do this task.

Approach #1 : Naive Approach

A naive method to create list within a given range is to first create an empty list and append successor of each integer in every iteration of for loop.

 `# Python3 Program to Create list ``# with integers within given range `` ` `def` `createList(r1, r2):`` ` `    ``# Testing if range r1 and r2 ``    ``# are equal``    ``if` `(r1 ``=``=` `r2):``        ``return` `r1`` ` `    ``else``:`` ` `        ``# Create empty list``        ``res ``=` `[]`` ` `        ``# loop to append successors to ``        ``# list until r2 is reached.``        ``while``(r1 < r2``+``1` `):``             ` `            ``res.append(r1)``            ``r1 ``+``=` `1``        ``return` `res``     ` `# Driver Code``r1, r2 ``=` `-``1``, ``1``print``(createList(r1, r2))`
Output:
```[-1, 0, 1]
```

Approach #2 : List comprehension

We can also use list comprehension for the purpose. Just iterate ‘item’ in a for loop from r1 to r2 and return all ‘item’ as list. This will be a simple one liner code.

 `# Python3 Program to Create list ``# with integers within given range `` ` `def` `createList(r1, r2):``    ``return` `[item ``for` `item ``in` `range``(r1, r2``+``1``)]``     ` `# Driver Code``r1, r2 ``=` `-``1``, ``1``print``(createList(r1, r2))`
Output:
```[-1, 0, 1]
```

Approach #3 : using Python `range()`

Python comes with a direct function `range()` which creates a sequence of numbers from start to stop values and print each item in the sequence. We use `range()` with r1 and r2 and then convert the sequence into list.

 `# Python3 Program to Create list ``# with integers within given range `` ` `def` `createList(r1, r2):``    ``return` `list``(``range``(r1, r2``+``1``))``     ` `# Driver Code``r1, r2 ``=` `-``1``, ``1``print``(createList(r1, r2))`
Output:
```[-1, 0, 1]
```

Approach #4 : Using `numpy.arange()`

Python numpy.arange() returns a list with evenly spaced elements as per the interval. Here we set the interval as 1 according to our need to get the desired output.

 `# Python3 Program to Create list ``# with integers within given range ``import` `numpy as np``def` `createList(r1, r2):``    ``return` `np.arange(r1, r2``+``1``, ``1``)``     ` `# Driver Code``r1, r2 ``=` `-``1``, ``1``print``(createList(r1, r2))`
Output:
```[-1  0  1]
```

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