# Python: Find the index of the first element in the given list that satisfies the provided testing function

## Python List: Exercise - 229 with Solution

Write a Python program to find the index of the first element in the given list that satisfies the provided testing function.

Use a list comprehension, enumerate() and next() to return the index of the first element in nums for which fn returns True.

**Sample Solution:**

**Python Code:**

```
# Define a function 'find_index' that takes a list 'nums' and a function 'fn' as input.
def find_index(nums, fn):
# Use a generator expression to find the first index 'i' where 'fn(x)' is True for an element 'x' in 'nums'.
return next(i for i, x in enumerate(nums) if fn(x))
# Call the 'find_index' function with an example list and a lambda function that checks if a number is odd.
print(find_index([1, 2, 3, 4], lambda n: n % 2 == 1))
```

Sample Output:

0

**Flowchart:**

**Python Code Editor:**

**Previous:** Write a Python program to get every element that exists in any of the two given lists once, after applying the provided function to each element of both.

**Next:** Write a Python program to find the indexes of all elements in the given list that satisfy the provided testing function.

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