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Python Introducing Lists Build an Application Multidimensional Musical Groups

Posted by teamz
teamz
44,723 Points

Musical Groups: Multi Dimensional Arrays in Python Lists

Hi All--

Arrays are about my least favorite thing in coding and I am having a hard time with this one.

I am not sure where I have gone wrong.

I am getting an AssertionError which is referencing printing and newlines, so not sure where I goofed up.

I have already rewatched the multidimensional array video again a couple of times without any luck.

Thanks!

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:
    group.join(", ")
    group += 1

1 Answer

Alex Koumparos
seal-mask
.a{fill-rule:evenodd;}techdegree
Alex Koumparos
Python Development Techdegree Student 36,887 Points
Alex Koumparos
.a{fill-rule:evenodd;}techdegree
Alex Koumparos
Python Development Techdegree Student 36,887 Points

Hi Teamz,

Your for-loop declaration is correct but once inside the loop you are making a couple of mistakes:
Firstly, join() in Python works differently (backward even) from what you might expect, especially if you've seen similar constructs in other languages. join() is a method on a string NOT a method on a list. This means that you apply join() TO ", " and then pass the list in to join as its argument.

This will give you a string, comprising the comma-separated band members. But you still need to do something with this string. The assertion error is giving you a clue what you should be doing with the string (hint: it rhymes with 'hint'...)

Lastly, you are incrementing group, which is invalid syntax (group is a list not an integer, so you can't add 1 to it), but even if it weren't syntactically wrong, it would be logically wrong. The for-in loop construct automatically moves to the next item in the list, you don't manually increment the loop index.

Hope that clears everything up

Cheers

Alex