﻿ Python: Make an iterator that drops elements from the iterable as long as a condition is true - w3resource

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

## Python Itertools: Exercise-7 with Solution

Write a Python program to make an iterator that drops elements from the iterable as long as the elements are negative; afterwards, it returns every element.

Sample Solution:

Python Code:

``````import itertools as it
def drop_while(nums):
return it.takewhile(lambda x : x < 0, nums)
nums = [-1,-2,-3,4,-10,2,0,5,12]
print("Original list: ",nums)
result = drop_while(nums)
print("Drop elements from the said list as long as the elements are negative\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("Drop elements from the said list as long as the elements are negative\n",list(result))
```
```

Sample Output:

```Original list:  [-1, -2, -3, 4, -10, 2, 0, 5, 12]
Drop elements from the said list as long as the elements are negative
[-1, -2, -3]
Original list:  [-1, -2, -3, 4, -10, 2, 0, 5, 12]
Drop elements from the said list as long as the elements are negative
[4, -10, 2, 0, 5, 12]
```

Python Code Editor:

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﻿

## Python: Tips of the Day

Inverts a dictionary with non-unique hashable values:

Example:

```def tips_collect_dictionary(obj):
inv_obj = {}
for key, value in obj.items():
inv_obj.setdefault(value, list()).append(key)
return inv_obj
ages = {
"Owen": 25,
"Jhon": 25,
"Pepe": 15,
}
print(tips_collect_dictionary(ages))
```

Output:

```{25: ['Owen', 'Jhon'], 15: ['Pepe']}
```

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