Professional IronPython

Working with the collections Module
 
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73
classes — something not discussed in this chapter. To give you an example of how the objects in 
the containers module work, this section discusses the 
deque
, which has the following methods 
associated with it.
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append()
: Appends a new item to the right side of the 
deque
.
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appendleft()
: Appends a new item to the left side of the 
deque
.
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clear()
: Removes all of the elements from the 
deque
and leaves the length at 0.
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extend()
: Adds elements to the right side of the 
deque
using an iterable argument, such as
a sequence.
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extendleft()
: Adds elements to the left side of the 
deque
using an iterable argument, such 
as a sequence. Adding items to the left side of the 
deque
reverses the order of the elements in 
the iterable argument. For example, if you have a 
list
that contains 
[‘a‘, ‘b‘, ‘c‘]
, this 
method will add them in the order 
[‘c‘, ‘b‘, ‘a‘]
.
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pop()
: Removes an item from the right side of the 
deque
and returns it as output to the 
caller. If the 
deque
is empty, this call will raise an 
IndexError
.
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popleft()
: Removes an item from the left side of the 
deque
and returns it as output to the 
caller. If the 
deque
is empty, this call will raise an 
IndexError
.
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remove()
: Removes the first occurrence of an item, starting from the left side of the 
deque
. If 
the 
deque
doesn’t contain the requested value, this method raises a 
ValueError
.
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