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 Introducing Lists Build an Application Multidimensional Musical Groups

Marcus De Silva
Marcus De Silva
1,717 Points
Posted by Marcus De Silva
Marcus De Silva
1,717 Points

Help with nested lists

I'm having trouble sorting out the length of the lists inside the list musical_groups. I want to check the length of the lists inside and print out the ones that contain only three elements. It wont accept my for loop though. Apparently, some of the lists with more elements are getting through. Any help would be appreciated.

groups.py 
musical_groups = [
    ["Ad Rock", "MCA", "Mike D."],
    ["John Lennon", "Paul McCartney", "Ringo Starr", "George Harrison"],
    ["Salt", "Peppa", "Spinderella"],
    ["Rivers Cuomo", "Patrick Wilson", "Brian Bell", "Scott Shriner"],
    ["Chuck D.", "Flavor Flav", "Professor Griff", "Khari Winn", "DJ Lord"],
    ["Axl Rose", "Slash", "Duff McKagan", "Steven Adler"],
    ["Run", "DMC", "Jam Master Jay"],
]
seperator = ", "
for record in musical_groups:
    x = seperator.join(record)
    print(x)

for trio in musical_groups:
    if len(trio) == 3:
        print(trio)

1 Answer

Peter Vann
Peter Vann
36,427 Points

Hi Marcus!

You have the right idea.

The tests are kinda strict, though.

You don't need the extra function.

Do both tasks with the same/existing loop.

This passes both tasks:

musical_groups = [
    ["Ad Rock", "MCA", "Mike D."],
    ["John Lennon", "Paul McCartney", "Ringo Starr", "George Harrison"],
    ["Salt", "Peppa", "Spinderella"],
    ["Rivers Cuomo", "Patrick Wilson", "Brian Bell", "Scott Shriner"],
    ["Chuck D.", "Flavor Flav", "Professor Griff", "Khari Winn", "DJ Lord"],
    ["Axl Rose", "Slash", "Duff McKagan", "Steven Adler"],
    ["Run", "DMC", "Jam Master Jay"],
]
seperator = ", "
for record in musical_groups:
    if len(record) == 3:
        x = seperator.join(record)
        print(x)

I hope that helps.

Stay safe and happy coding!

Marcus De Silva
Marcus De Silva
1,717 Points
Marcus De Silva
Marcus De Silva
1,717 Points

Thank you so much! You stay safe as well!