Python List:

A list is a collection of elements which is ordered and changeable.

List in python is mutable.

In Python lists are written with square brackets.

Example:

list1 = ["book", "copy", "pen"]

print(list1)

Output:

["book", "copy", "pen"]

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Accessing Items in list:

In list we can access items with the help of their index number.

The indexing of list start from zero.

Example:

list1 = ["book", "copy", "pen"]

print(list1[1])

Output:

["copy"]

Note:The index number of list should put in square bracket.In above example we can see that at [1] index "copy" is present which means that the indexing of list start from 0. 

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Using of For Loop in List:

Example:

list1 = ["book", "copy", "pen"]

for x in list1[1]:
      print(x)

Output:

book
copy
pen

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Negative Indexing of list:

Negative indexing means beginning from the end -1 and -2 refers to the second last item and so on.


Example:

list1 = ["book", "copy", "pen"]

print(list1[-1])

Output:

["pen"]

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Specifying Range of Indexes:

Example:

list1 = ["book", "copy", "pen", "scale", "pencil"]

print(list1[1:4])

Output:

["copy", "pen", "scale"]

#This will return the items from position 1 to 4.

#Remember that the first item is position 0,and note that the item in position 5 is not included

#Similarly,we can do it for negative index.

Example:

list1 = ["book", "copy", "pen", "scale", "pencil"]

print(list1[-4:-1])

Output:

["copy", "pen", "scale"]

#This example returns the items from index -4 which is included and index -1 is excluded.
#Remember that the last item has the index -1.

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Changing Item in list:

Example:

list1 = ["book", "copy", "pen"]

list1[0] = "scale"

print(list1)

Output:

["scale", "copy", "pen"]

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Checking Item exists in list or not:

To determine if a item is present in a list we use the in keyword:

Example:

list1 = ["book", "copy", "pen"]

if "copy" in list1:

     print("Yes, 'copy' is in the list")

Output:

Yes, 'copy' is in the list

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Length of list:

To determine how many items are present in list we use the len() method:

Example:

list1 = ["book", "copy", "pen"]

print(len(list1))

Output:

3

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Adding Items in list:

To add an item to the end of the list, use the append() method:

Example:

list1 = ["book", "copy", "pen"]

list1.append("scale")

print(list1)

Output:

["book", "copy", "pen", "scale"]

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Inserting Items in list:

To add an item at particular index we use the insert() method:

Example:

list1 = ["book", "copy", "pen"]

list1.insert(1, "scale")

print(list1)

Output:

["book", "scale", "copy", "pen"]

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Remove Item from list:

To remove an item from list we use the remove() method:

Example:

list1 = ["book", "copy", "pen", "scale"]

list1.remove("scale")

print(list1)

Output:

["book", "copy", "pen"]

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pop( ) method for list:

pop() method remove the particular index item or last item if index is not specified.

Example:

list1 = ["book", "copy", "pen", "scale"]

list1.pop()

print(list1)

Output:

["book", "copy", "pen"]

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del( ) method for list:

Example 1:

list1 = ["book", "copy", "pen", "scale"]

list1.del[3]

print(list1)

Output:

["book", "copy", "pen"]

Example 2:

list1 = ["book", "copy", "pen", "scale"]

del (list1)

print(list1)

Output:

# This will cause error as list has been deleted.

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clear( ) method for list:

clear() method clear the whole list.

Example:

list1 = ["book", "copy", "pen", "scale"]

list1.clear()

print(list1)

Output:
[ ]

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Copying a list into another:

copy() method copy the list.

Example:

list1 = ["book", "copy", "pen", "scale"]

list2 = list1.copy()

print(list2)

Output:

["book", "copy", "pen", "scale"]

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count( ) method for list:

count() method count the element repetition in list.

Example:

list1 = ["book", "copy", "pen", "scale", "pen"]

x = list1.count("pen")

print(x)

Output:

2

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extend( ) method in list:

extend() method add one list to the another list.

Example:

list1 = ["book", "copy", "pen"] 
list2 = ["scale", "pen"]

list1.extend(list2)

print(x)

Output:

["book", "copy", "pen", "scale", "pen"]

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index( ) method in list:

index() method  returns the position of element in list.

Example:

list1 = ["book", "copy", "pen", "scale"]
x = list1.index("pen")
print(x)

Output:
2

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reverse( ) method in list:

reverse() method  returns the position of element in list.

Example:

list1 = ["book", "copy", "pen"]

list1.reverse("pen")

print(list1)

Output:

["pen", "copy", "book"]

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sort() method for list:

sort() method sorts the list in ascending order by default.

Example:

list1 = ["pen", "copy", "book"]

list1.sort()

print(list1)

Output:

["book", "copy", "pen"]

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list( ) Constructor:

list() constructor to make a new list.

Example:

list1 = list(("pen", "copy", "book"))

print(list1)

Output:

["pen", "copy", "book"]

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