﻿ Python: Symmetric difference between two lists, after applying the provided function to each list element of both - w3resource

# Python: Symmetric difference between two lists, after applying the provided function to each list element of both

## Python List: Exercise - 227 with Solution

Write a Python program to get the symmetric difference between two lists, after applying the provided function to each list element of both.

• Create a set by applying fn to each element in every list.
• Use a list comprehension in combination with fn on each of them to only keep values not contained in the previously created set of the other.

Sample Solution:

Python Code:

``````def symmetric_difference_by(a, b, fn):
(_a, _b) = (set(map(fn, a)), set(map(fn, b)))
return [item for item in a if fn(item) not in _b] + [item
for item in b if fn(item) not in _a]
from math import floor
print(symmetric_difference_by([2.1, 1.2], [2.3, 3.4], floor))
```
```

Sample Output:

```[1.2, 3.4]
```

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## Python: Tips of the Day

Given a predicate function, fn, and a prop string, this curried function will then take an object to inspect by calling the property and passing it to the predicate:

Example:

```def tips_check_prop(fn, prop):
return lambda obj: fn(obj[prop])
check_age = tips_check_prop(lambda x: x >= 25, 'age')
user = {'name': 'Owen', 'age': 25}

print(check_age(user))
```

Output:

```True
```

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