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)) |
[-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)) |
[-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)) |
[-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)) |
[-1 0 1]
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