iter

This module includes tools for acting with iterators and collections.

isfirst

This class wrapps your iterator and turns it into another one, which iterates not only over the original data, but also over boolean flag which equals True for the first element and False for remaining elements.

For example:

>>> items = ['One', 'Two', 'Three']
>>> for item, first in isfirst(items):
...     if first:
...         print(item.upper())
...     else:
...         print(item)
ONE
Two
Three

islast

This class should be used by analogy to the one described in isfirst. Please note that islast invokes len function on the original iterator, which means that the iterator must provide this functionality.

For example:

>>> items = ['One', 'Two', 'Three']
>>> for item, last in islast(items):
...     if last:
...         print(item.upper())
...     else:
...         print(item)
One
Two
THREE

isfirstlast

Wrappers isfirst and islast can be combined to provide cumulative functionality.

For example:

>>> items = ['One', 'Two', 'Three']
>>> for (item, first), last in islast(isfirst(items)):
...     if first:
...         print(item.upper())
...     elif last:
...         print(item.lower())
...     else:
...         print(item)
ONE
Two
three

Alternatively isfirstlast class can be used to get the same results and make syntax more readable.

For example:

>>> items = ['One', 'Two', 'Three']
>>> for item, first, last in isfirstlast(items):
...     if first:
...         print(item.upper())
...     elif last:
...         print(item.lower())
...     else:
...         print(item)
ONE
Two
three

iget

Get index-nth element from iterable.

For example:

>>> g = range(10)
>>> iget(g, 5)
5

>>> def genfunc():
...     while True:
...         yield from 'abcd'
>>> g = genfunc()
>>> iget(g, 2)
'c'