How Can I Access Element Indices While Iterating with Python's `for` Loop?

Accessing Element Indices in 'for' Loops in Python

How do we access the index of an element while iterating over a sequence using a 'for' loop in Python? Let's delve into the solution below:

Consider the Python code snippet:

xs = [8, 23, 45]

for x in xs:
    print("item #{} = {}".format(index, x))

The goal is for this code to print the following output:

item #1 = 8
item #2 = 23
item #3 = 45

However, the above code will result in an error, as the variable 'index' is not defined within the loop. To address this issue, we can employ Python's enumerate function:

for idx, x in enumerate(xs):
    print(idx, x)

enumerate provides a convenient means of iterating over a sequence, assigning an index (starting from 0) to each element as it loops. In the modified code above, 'idx' now represents the index value.

While it might be tempting to implement manual indexing using 'for i in range(len(xs))' loops and manually accessing elements at 'xs[i]', it's considered non-Pythonic. Python encourages the use of idioms like enumerate whenever possible, offering both concise and efficient solutions.

For more insights on this topic, refer to PEP 279:

• [Iteration Protocol](https://www.python.org/dev/peps/pep-0279/#special-semantics)

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