[Tutor] List weirdness

[Alan Gauld]

"Moos Heintzen" <iwasroot at gmail.com> wrote 

> >>> d = [[]]
> >>> d[0][0]=1
> IndexError: list assignment index out of range
> >>> d[0].append(1)
> >>> d
> [[1]]
> 
> I guess I can't reference [0] on an empty list. 

Thats right. You can't assign a value to a position in 
a list that hasn't been created yet. It has nothing to 
do with nesting, its the same for a simople lust:

>>> lst = []
>>> lst[0] = 66
Traceback (most recent call last):
  File "<input>", line 1, in <module>
IndexError: list assignment index out of range
>>> lst.append(66)
>>> lst
[66]
You can also use insert, which takes an index. 
But if the index is non existent it appends...

>>> lst2 = []
>>> lst2.insert(3,66)
>>> lst2
[66]
>>> lst.insert(3,66)
>>> lst
[66, 66]
>>> 

HTH,


-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/