Sorting

All the decorators in this category take a single keyword argument duplicate_values, a boolean value that indicates whether or not the sorting algorithm removes extra duplicate values. The default is True, meaning duplicate values are allowed, and not removed.

Comparison function decorators

The following three decorators, mergesort, mergesort_map, and mergesort_index are all used to decorate a comparison function that follows the signature stipulated below.

The decorated comparator must have the signature (a,b), and must return either -1, 0, or 1, indicating the following:

Returned	Interpretation
0	a = b
-1	a < b
1	a > b

These decorators change the signature of the function they decorate, therefore if they are used to decorate a class method, @staticmethod must be stacked on top like this:

class Sorter():

    @staticmethod
    @pydecorator.mergesort(duplicate_values=True)
    def sort(a,b):
        return 1 if a > b else -1 if a < b else 0

mergesort

The decorated function will have the signature (array), where array is either a generator or an indexable collection. The function will return the input as a sorted list:

@pydecorator.mergesort(duplicate_values=False)
def sorted_set(a,b):
    return 1 if a > b else -1 if a < b else 0

>>> sorted_set([1,3,0,1,2])
[0, 1, 2, 3]

mergesort_map

The decorated function will have the signature (array), where array is either a generator or an indexable collection. The function will return a list of integers, each within the range (0 ,..., len(array)-1). Each int in the returned array of the returned each corresponding to an index the input as a sorted list:

@pydecorator.mergesort_map(duplicate_values=True)
def sorted_map(a,b):
    return 1 if a > b else -1 if a < b else 0

>>> test = ['b','d','a','b','c']
>>> test
['b', 'd', 'a', 'b', 'c']
>>> index = sorted_map(test)
>>> index
[2, 0, 3, 4, 1]
>>> [test[i] for i in index]
['a', 'b', 'b', 'c', 'd']

mergesort_index

The decorated function will have the signature (index,array), where array is either a generator or an indexable collection, and index is an indexable collection of integers, each within the range (0 ,..., len(array)-1), corresponding to an element in array. The function will return the input index, in sorted order (when mapped to array). A simple example:

@pydecorator.mergesort_index(duplicate_values=False)
def sorted_indexes(a,b):
    return 1 if a > b else -1 if a < b else 0

>>> test = ['b','d','a','b','c']
>>> test
['b', 'd', 'a', 'b', 'c']
>>> index = sorted_indexes(range(len(test)),test)
>>> index
[2, 0, 4, 1]
>>> [test[i] for i in index]
['a', 'b', 'c', 'd']

Note

The mergesort_index decorator is meant to be used to create functions that are part of more complex routines, such as sorting multi-dimensional data, and does not have much of a practical application as a standalone function. Use mergesort_map instead.

sorted

This function can decorate either a generator function or a function that returns an indexable collection. It preserves the decorated functions signature. Here’s a simple example:

@pydecorator.sorted(duplicate_values=False)
def make_list():
    return [1,0,3,5,1]

>>> make_list()
[0, 1, 3, 5]