Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Python Python Sequences Sequence Operations Creating Slices

Posted by Stephani Dudrak
Stephani Dudrak
1,614 Points

How do I know what elements I need?

I need to make a slice of the 3rd through 5th elements in the list. But does that mean 3rd starting at 1 like a human, or starting at 0 like Python? I tried slicing [3:6] and got an 'incorrect values' answer, so I tried [4:6] and [4:7] and got the same result.

slices.py 
student_gpas = [4.0, 2.3, 3.5, 3.7, 3.9, 2.8, 1.5, 4.0]
sliced_gpas = student_gpas[4:6]

1 Answer

Steven Parker
Steven Parker
229,732 Points
Steven Parker
Steven Parker
229,732 Points

You're right about "starting at 0 like Python", so that means the third element would have an index of  2 . And since slices are exclusive of the stop value, and the final index should be 4, then the stop value is  5 .

sliced_gpas = student_gpas[2:5]
Stephani Dudrak
Stephani Dudrak
1,614 Points

I was adding 1 to the wrong number, oops. Thanks for breaking it down. Wish there was a better way to explain that we want the third item in the list according to humans, second according to Python.

Steven Parker
Steven Parker
229,732 Points
Steven Parker
Steven Parker
229,732 Points

It's still the 3rd item to Python, it just starts counting with 0 for the first.