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

Chelsea Yang
Chelsea Yang
2,982 Points
Posted by Chelsea Yang
Chelsea Yang
2,982 Points

For the 2-d printout, why 2nd loop has to be inside ()

Can someone help why this way doesn't work? for group in musical_groups: for name in group: print(', '.join(str(name)));

but by placing the 2nd loop inside join() it passed for group in musical_groups: print(', '.join(str(name)for name in group));

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"],
]
# Your code here
for group in musical_groups:
    print(', '.join(str(name)for name in group));

1 Answer

Steven Parker
Steven Parker
231,269 Points
Steven Parker
Steven Parker
231,269 Points

Your first example doesn't work because it references "name", which has not been defined.

But while the generator expression works, it's more complicated than necessary since "group" is already a list of strings:

    print(', '.join(group))

And what's with that semicolon at the end of the line? That's not Python syntax.