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Python Lists

As the name suggests, the List is the collection of homogeneous or heterogeneous types of values. For example we have a list and the variable name for the list is names, like

names=[]

here list is identified by the square bracket symbol, and the [](square bracket) will contain the collection of values.
A list have zero values or maximum of values like 100 values, 1000 values etc.

For example;
>>> names=[]
>>> names[]


python lists

Here this is an empty list that we got when we call names .
Now we can initialize list, that means we can assign values to list.

For example,
>>> names=["Sashi","John","Alex"]
>>> names
['Sashi', 'John', 'Alex']          # output when we call names

Now this list having 3 values.
Now there is a term index in python list that represents the position of the value in list. Here position of list starting from 0 then 1, then 2, and so on.

For example:
>>> names[0]
'Sashi'
>>> names[1]
'John'
>>> names[2]
Alex


Now there is an interesting thing that you can have backward index also, that means we can traverse a list from backward direction. In backward direction index is starting from -1, then -2, then -3, and so on.

For example:
>>> names[-1]
'Alex'
>>> names[-2]
'John'
>>> names[-3]
'Sashi'
Here in our context, the forward index starts from 0 then 1 then 2, and backward index starts from -1 then -2 then -3.


Now I want to add a new data item, then we call append() : an in-built function in Python, like

>>> names.append("Sanghamitra")
>>> names
['Sashi', 'John', 'Alex', 'Sanghamitra']

Let we have another list and the variable name for the list is age, like

>>> age=[20,25,30,35]

Now we want to pass list age in list names, for this we call extend() function

>>> age=[20,25,30,35]
>>> names.extend(age)
>>> names
['Sashi', 'John', 'Alex', 'Sanghamitra', 20, 25, 30, 35]


Now we want to remove an item from a list, then we call remove() function.

For example:
>>> names.remove("John")
>>> names
['Sashi', 'Alex', 'Sanghamitra', 20, 25, 30, 35]
Now we want to print multiple lists
>>> print(names)
['Sashi', 'Alex', 'Sanghamitra', 20, 25, 30, 35]
>>> print(names,age)
['Sashi', 'Alex', 'Sanghamitra', 20, 25, 30, 35] [20, 25, 30, 35]


To find the length of list, we call len() function. The number of data items present in a list is the length of list.


For example:
>>> len(names)
7
To get the maximum and minimum value, we call max() and min()function.
>>> max(age)
35
>>> min(age)
20

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