We are going to learn a data structure called list before we go ahead to learn more on looping. Lists an be written as a list of comma-separated values (items) between square brackets.
>>> a = [ 1 , 342, 2233423, 'India', 'Fedora']
>>> a
[1, 342, 2233423, 'India', 'Fedora']
Lists can keep any other data inside it. It works as a sequence too, that means
>>> a[0]
1
>>> a[4]
'Fedora'
You can even slice it into different pieces, examples are given below
>>> a[4]
'Fedora'
>>> a[-1]
'Fedora'
>>> a[-2]
'India'
>>> a[0:-1]
[1, 342, 2233423, 'India']
>>> a[2:-2]
[2233423]
>>> a[:-2]
[1, 342, 2233423]
>>> a[0::2]
[1, 2233423, 'Fedora']
In the last example we used two :(s) , the last value inside the third brackets indicates step.
s[i:j:k] means slice of
s from
i to
j with step
k.
To check if any value exists within the list or not you can do
>>> a = ['Fedora', 'is', 'cool']
>>> 'cool' in a
True
>>> 'Linux' in a
False
That means we can use the above statement as
if clause expression. The built-in function
len() can tell the length of a list.
>>> len(a)
3
If you want to test if the list is empty or not, do it like this
if list_name: #This means the list is not empty
pass
else: #This means the list is empty
pass
