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join multidimensional lists

When I run the first code, is printing all the members, as requested. However, for the second code, instead of printing only the first, third and the seventh line only once, is printing it repeatedly and I am getting an error . What am I doing wrong?

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"],

for groups in musical_groups:
    print(", ".join(groups))

for groups in musical_groups:    
    print(", ".join(musical_groups[0])+","+",".join(musical_groups[2])+","+",".join(musical_groups[6]))

1 Answer

Your being ask to print only the groups that contains 3 elments and u can do it by chekcing the length of each group in the for loop.

for groups in musical_groups:
    if(len(group) === 3):
        print(", ".join(groups))

Thank you! That was very helpful.