Python: Make an iterator that drops elements from the iterable as soon as a condition is true

Last update on December 21 2024 07:31:08 (UTC/GMT +8 hours)

Write a Python program to make an iterator that drops elements from the iterable as soon as an element is a positive number.

Sample Solution:

Python Code:

import itertools as it
def drop_while(nums):
    return it.dropwhile(lambda x : x < 0, nums)
nums = [-1,-2,-3,4,-10,2,0,5,12]
print("Original list: ",nums)
result = drop_while(nums)
print("Drops elements from the iterable when a positive number arises \n",list(result))
#Alternate solution
def negative_num(x):
    return x < 0
def drop_while(nums):
    return it.dropwhile(negative_num, nums)
nums = [-1,-2,-3,4,-10,2,0,5,12]
print("Original list: ",nums)
result = drop_while(nums)
print("Drops elements from the iterable when a positive number arises \n",list(result))

Sample Output:

Original list:  [-1, -2, -3, 4, -10, 2, 0, 5, 12]
Drops elements from the iterable when a positive number arises 
 [4, -10, 2, 0, 5, 12]
Original list:  [-1, -2, -3, 4, -10, 2, 0, 5, 12]
Drops elements from the iterable when a positive number arises 
 [4, -10, 2, 0, 5, 12]

Python Code Editor:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous: Write a Python program to generate an infinite cycle of elements from an iterable.
Next: Write a Python program to make an iterator that drops elements from the iterable as long as the elements are negative; afterwards, returns every element.