Newbie Here, need clarification please

Python Help
1

Hello, I am trying to teach myself python. I am needing a little clarification on this:

a = ['a', 'b', 'c']
 >>> n = [1, 2, 3]
 >>> x = [a, n] 
>>> x
 [['a', 'b', 'c'], [1, 2, 3]]
 >>> x[0] 
['a', 'b', 'c'] 
>>> x[0][1]
 'b'

I understand up until the >>> x[0] results being [‘a’, ‘b’, ‘c’]
I even understand the next line …[1] being ‘b’
Maybe it is so obvious that I am over complicating it. IDK
Does the zero mean all characters after the zero position?
Thanks for any help!

2

No. Zero means ‘the first index position only’. If you want ‘all “items” after the zero position’, you use [1:], as in:

>>> x = [0,1,2,4,5,6]
>>> x[1:]
[1, 2, 4, 5, 6]

This x[0][1] means ‘the second position of the first list’, given that you have a nested list.

3

Im confused, if the zero means the first index position why does it return [‘a’, ‘b’, ‘c’]? Why not just [‘a’]?

4

Because (as I say), you have a ‘nested list’: that is to say you have two list object, within another list object. So, [0] is returning ‘the first list object’.

x = [a, n] has created a list object that contains the other two list objects.

5

ahhh! I get it now.
a[0] would be ‘a’
n[0] would be '1;
and x[0] is nested list ‘a’ so its ‘a’,‘b’,‘c’

6

any suggestions on books or websites to help me learn?
Right now im using python.org tutorial.

thanks

7

Way-to-go! You’ve got it.

A couple of sites that I’d recommend:

8

Because (as I say), you have a ‘nested list’: that is to say you have
two list object, within another list object. So, [0] is returning
‘the first list object’.

x = [a, n] has created a list object that contains the other two list
objects.

To make this a bit more clear maybe, your first post showed this:

 >>> x
 [['a', 'b', 'c'], [1, 2, 3]]

Laid out more elaboratedly:

 [
   ['a', 'b', 'c'],  # this is x[0]
   [1, 2, 3]         # this is x[1]
 ]

so for example x[1][1] is [1,2,3][1] which is 2.

Cheers,
Cameron Simpson cs@cskk.id.au

9

Okay, thank you.

10

Thanks everyone!

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