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Python Introducing Lists Build an Application Multidimensional Musical Groups

Posted by Randall Varasteh
.a{fill-rule:evenodd;}techdegree
Randall Varasteh
Python Development Techdegree Student 2,814 Points

.join() help

On the challenge: Here is a multi-dimensional list of musical groups. The first dimension is group, the second is group members. Can you loop through each group and output the members joined together with a ", " comma space as a separator, please?

I'm confused about how the join function works in loops, and have tried other variations of my code attached, but I keep receiving the error: File "", line 13, in TypeError: sequence item 0: expected str instance, list found

I went back and re-watched both videos on multi-dimensional lists and the join function, as well as googled the function. I'm not sure what I'm not understanding. Please help, 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 band in musical_groups:
    seperator = ", "
    bands = seperator.join(musical_groups)
    print(bands)

1 Answer

Jassim Alhatem
Jassim Alhatem
20,883 Points

Hi Randall Varasteh,

You should take out the musical_groups and replace it with band. You got everything right, you just messed up with the iterable.

Your code should be:

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 band in musical_groups:
    seperator = ", "
    bands = seperator.join(band)
    print(bands)

Check out GeeksforGeeks. They give a very good explanation of the .join() function.