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Python Python Collections (2016, retired 2019) Lists Growing Lists

Posted by isaacrichardson
isaacrichardson
14,313 Points

How do you user the .insert() and del method in a 2d list

Thank you

1 Answer

Steven Tagawa
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Steven Tagawa
Python Development Techdegree Graduate 14,438 Points
Steven Tagawa
.a{fill-rule:evenodd;}techdegree seal-36
Steven Tagawa
Python Development Techdegree Graduate 14,438 Points

I was curious about this, so I played around a bit in the REPL, and this is what I found.

To use .insert, you have to identify the first index in the variable name. So let's say you have a 2D list called my_list, like so:

my_list = [[1, "first", "1st"], [2, "second", "2nd"], [3, "third", "3rd"]]

...and you want to insert the word "bananas" between "second" and "2nd". In this case your first index is [1] (second list) and your second index is [2] (between the second and third items). To insert at position [1][2], you would say:

my_list[1].insert(2, "bananas")

...which would stick "bananas" before the third item in the second list.

Del is a lot simpler: you just pass both indices. The word "bananas" in my_list is at position [1][2], so to get rid of it you just say:

del(my_list[1][2])

...and it's gone.

Hope this helps!