Print alternate elements in the list (raising IndexError: list index out of range)

Question

How do I print every other item in a list without it giving me this error?

Im confused, I have tried this a million times in a million different ways, but same answer. My code right now:

item = 0
fruit = ['Strawberry','apple','pear','orange','banana','cucumber','tomato','Kiwi']
for count in fruit:
    print(fruit[item])
    item = item + 2

Any ideas?

Answer 1

You may use slicing feature of list, i.e. you may slice your list content as:

your_list[start:end:step]

which in simple words will create a new list:

• starting from index start
• upto index end
• with step of step

For more information, read: Python's slice notation

In your case, you can iterate over the sliced list with step of 2. You do not need index as a pointer to your list as your for will do it for you. Your code will look like this:

>>> fruit = ['Strawberry','apple','pear','orange','banana','cucumber','tomato','Kiwi']
>>>
>>> for f in fruit[::2]:
...     print f
...
Strawberry
pear
banana
tomato

Here fruit[::2] holds the value:

['Strawberry', 'pear', 'banana', 'tomato']

---

Edit: Reason for the failure of your code is, you are iterating over the entire list let's say of n length. But you are accessing the item at the twice the index of your current position. When you will be on n/2 th element, you will try to access item as fruit[n], which will raise IndexError as your list was holding item only upto n-1 th index.

Answer 2

If you wish to iterate over fruit by skipping every 2 elements, you may proceed like below:

for item in fruit[::2]:
    print(item)

Answer 3

The reason your code doesn't work is because

for count in fruit:

iterates over each item in the fruit list, so once you're at the half-way point, item will point beyond the end of the list. Here's a modified version of your code to illustrate:

item = 0
fruit = ['Strawberry', 'apple', 'pear', 'orange', 'banana', 'cucumber', 'tomato', 'Kiwi']
print(len(fruit))
for v in fruit:
    print(v, item)
    item = item + 2

output

8
Strawberry 0
apple 2
pear 4
orange 6
banana 8
cucumber 10
tomato 12
Kiwi 14

So once we reach "banana", fruit[item] will try to access an item beyond the end of fruit, and that raises an IndexError exception.

---

As others have mentioned, the usual way to do this task in Python is to use extended slicing:

fruit = ['Strawberry', 'apple', 'pear', 'orange', 'banana', 'cucumber', 'tomato', 'Kiwi']

for v in fruit[::2]:
    print(v)

output

Strawberry
pear
banana
tomato

If you want the odd items, you can start the slice at 1:

for v in fruit[1::2]:
    print(v)

output

apple
orange
cucumber
Kiwi

Or you can just print a slice, as is, since it's just a list:

print(fruit[::2])

output

['Strawberry', 'pear', 'banana', 'tomato']

Answer 4

There was a slight mistake in your code in the print statment:

item = 0
fruit = ['Strawberry','apple','pear','orange','banana','cucumber','tomato','Kiwi']
for item in fruit[0::2]:
    print(item)

Output:

Strawberry
pear
banana
tomato