Python: Make an iterator that drops elements from the iterable as soon as a condition is true
Python Itertools: Exercise-6 with Solution
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:
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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.
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Python: Tips of the Day
Find current directory and file's directory:
To get the full path to the directory a Python file is contained in, write this in that file:
import os dir_path = os.path.dirname(os.path.realpath(__file__))
(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)
To get the current working directory use
import os cwd = os.getcwd()
Documentation references for the modules, constants and functions used above:
- The os and os.path modules.
- The __file__ constant
- os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
- os.path.dirname(path) (returns "the directory name of pathname path")
- os.getcwd() (returns "a string representing the current working directory")
- os.chdir(path) ("change the current working directory to path")
Ref: https://bit.ly/3fy0R6m
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