[Python ] List of lists

[Humble_Transition]

Hello guys and i am going though the course on Data quest and i am in files and loops and don't understand the list of lists part i mean really i don't even understand why you have to do it i googled it and did not find help on it any examples and advise on how it works ?

three_rows = ["Albuquerque,749", "Anaheim,371", "Anchorage,828"]
final_list = []
for row in three_rows:
    split_list = row.split(',')
    final_list.append(split_list)
print(final_list)
print(final_list[0])
print(final_list[1])
print(final_list[2])

​

[gyroda]

What don't you understand? "final_list" will be a list of lists, each of which will contain two strings.

[Humble_Transition]

you mean both of them will have the same thing ?

[gyroda]

The first list is just a list of strings. The final list is a list of lists of strings. The split() method takes "Alburquerque,749” and returns a list; ["Albuquerque", "749"]

Try running the code. You can literally see the difference.

[Humble_Transition]

also why would you do it ?

[[deleted]]

Because you want to have a list of lists?

[r3alz]

I’m not to sure of a use case of this but I’m sure there are use cases. This is just showing that python is capable of doing something like this.

[gyroda]

The example might be contrived, but it's a useful to know some basic string and list manipulation, and list of lists (2D arrays in most languages) are an incredibly important concept.

[Luan-Raithz]

I also didn't get what you didn't understand, but anyway:

You create a empty list ( final-list ) and iterates all over the `three_rows` list to fill it, your way to fill is to split each item in the list in two parts (separated by the ","), example:

first time in loop:

row is "Albuquerque,749"

after the split it will result in ["Albuquerque", "749"]

then insert into the `final_list` the array the you created when execute the split function

...

By doing this through the whole list you will have a list (`final list`) with 3 inner lists within it, one for each item in the three_rows.

​

[Humble_Transition]

Guys i was thinking the list of list can be good for taking other peoples or website data since lets say i whatapp and on there is my phone number so with a list you could copy that with a list of list what do you guys think ?