Python: finding an element in a list

>>> li
[a, b, new, mpilgrim, z, example, new, two, elements]
>>> li.index(example)
5

If you just want to find out if an element is contained in the list or not:

>>> li
[a, b, new, mpilgrim, z, example, new, two, elements]
>>> example in li
True
>>> damn in li
False

The best way is probably to use the list method .index.

For the objects in the list, you can do something like:

def __eq__(self, other):
    return self.Value == other.Value

with any special processing you need.

You can also use a for/in statement with enumerate(arr)

Example of finding the index of an item that has value > 100.

for index, item in enumerate(arr):
    if item > 100:
        return index, item