Today our python built-in function is enumerate() which is very much useful to generate iterator element along with index.

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**Need of enumerate() function in Python:**

Some times we require to generate a sequence of elements in a list or tuple along with their index. Let us see an example. I have a list L1=[23, 56, ‘surendra’, ‘test’, ‘abc’] and I want to generate an output as

0 231 562 surendra3, test4 abc

To get this output, we have to depend on len() and range() functions as shown below.

>>> for i in range(len(L1)):

... print i, L1[i]

...

0 23

1 56

2 surendra

3 test

4 abc

This can be achieved with enumerate() function as well.

**Python enumerate() function syntax:**

enumerate(iterator, index-number)

**Examples:** Let us start with enumerate() function with some examples and see how we can use these examples in Python coding.

**Example1: **Enumerate a list along with it’s index

>>> for i, item in enumerate(L1):

... print i, item

...

0 23

1 56

2 surendra

3 test

4 abc

**Example2:** Select index instead of default index

>>> [[i,j] for i,j in enumerate(L1, 3)]

[[3, 23], [4, 56], [5, 'surendra'], [6, 'test'], [7, 'abc']]

**Example3: **Generate a list of tuples each tuple have index and it’s element.

>>> [(i,j) for i, j in enumerate(L1)]

[(0, 23), (1, 56), (2, 'surendra'), (3, 'test'), (4, 'abc')]

**Example4:** Generate a list of lists with each list containing list element and it’s index

>>> [[i,j] for i, j in enumerate(L1)]

[[0, 23], [1, 56], [2, 'surendra'], [3, 'test'], [4, 'abc']]

**Example5:** Generate sets from a list of which each set contain list element and it’s index

>>> [{i,j} for i, j in enumerate(L1)]

[set([0, 23]), set([56, 1]), set([2, 'surendra']), set(['test', 3]), set(['abc', 4])]

**Example6:** Generate a dictionary from a list of which contain index as dictionary key and element as dictonary value.

>>> {i:j for i, j in enumerate(L1)}

{0: 23, 1: 56, 2: 'surendra', 3: 'test', 4: 'abc'}

or

>>> dict(enumerate(L1))

{0: 23, 1: 56, 2: 'surendra', 3: 'test', 4: 'abc'}

**â€‹Related functions: list(), tuple(), set(), dict()**

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