﻿ Python: Check if a given function returns True for every element in a list - w3resource

# Python: Check if a given function returns True for every element in a list

## Python List: Exercise - 243 with Solution

Write a Python program to check if a given function returns True for every element in a list.

Use all() in combination with map() and fn to check if fn returns True for all elements in the list.

Sample Solution:

Python Code:

``````def every(lst, fn = lambda x: x):
return all(map(fn, lst))
print(every([4, 2, 3], lambda x: x > 1))
print(every([4, 2, 3], lambda x: x < 1))
print(every([4, 2, 3], lambda x: x == 1))
```
```

Sample Output:

```True
False
False
```

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The following tool visualize what the computer is doing step-by-step as it executes the said program:

Python Code Editor:

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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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