List for Beginner

Python
1

vec=[ele1,ele2,[subele1,subele2]]
print (vec [2][1])

Please help,why does
(vec[0]) identifies ele1 ,but not both ele1 AND ele 2
while when we put
(vec[2]) it identifies both subele AND subele 2
Why does sublist is identified as the one whole member and to take separetely subele1,for instance, we should do like that (vec[1])?What is the logic?Please explain,I am a kettle.

2

You have a three elements list.
The first element of your list is ele1
The second element is ele2
The third element is the list [subele1, subele2], so you have an element that is a list.

Python uses zero base index, that means that start to count from zero, so for the Python interpreter your elements are called in the follow way:

>>>my_list = ['element1', 'element2', ['subelement1', 'subelement2']]
>>>print(my_list[0])
element1
>>>print(my_list(1)]
'element2'
>>> print(my_list[2])
['subelement1', 'subelement2']
>>> print(my_list[2][0])
subelement1

The last print accesses to the first element of the third element, in zero base index that is the index 2-0

You can google Python Zero base index and you will have lot of information. That applies for all number indexed structures in Python, including strings and lists.

2 Likes
3

OK,I got this.But why doesn`t python identify ele1 and ele2 the whole list,so 1 whole element in the same way as it identifies subele1 and subele2 one element?What is the difference?Thank you for help!

4

Elements are separated by commas, if you check after last comma there is a list, it means that the third element is that list - it is a case of nested lists