Python built-in functions sorted sort usage

python:sort,sorted,ordereddict Usage – May 13, 2011 20:58 from http://stqdd.com/archives/427 by Moya Dish

Python has two kinds of data in the container, one is the container's own sort function, one is the built-in sorted function.

The only difference between the sort function and the sorted function is that sort is sorted within the container, sorted generates a new ordered container.

For a simple array of l=[5,2,3,1,4].

Sort:l.sort ()

Sorted (...)
Sorted (iterable, Cmp=none, Key=none, Reverse=false)--> new sorted list

Iterable: An iterative type of container to be sorted;
CMP: A function For comparison, comparing what is determined by the key, having a default value, and an item in the iteration set;
Key: Use a named property or function of a list element (with only one parameter and return a value for sorting) as a keyword, with a default value, an item in the iteration set;
Reverse: Sorting rules. Reverse = True or reverse = False, with default values.
Return value: Is a sorted, iterative type, similar to iterable.

If it is a multidimensional list l=[(' B ', 2), (' A ', 1), (' C ', 3), (' d ', 4)].

There are three options for sorting this multidimensional list using CMP functions

Sorted (L, Cmp=lambda x,y:cmp (x[1],y[1))

L.sort (Cmp=lambda x,y:cmp (x[1],y[1)) utilizes key

Sorted (L, Key=lambda x:x[1]);

L.sort (Key=lambda x:x[1]); Reverse order

The above sorts all can add parameter reverse.

For example sorted (reverse=true), L.sort (reverse=true). or change it to false.

Ordereddict is a package in collections that can record the order in which dictionary elements are inserted, often used with sort functions to generate a sorted dictionary.

For example, an unordered dictionary.

D = {' Banana ': 3, ' Apple ': 4, ' pear ': 1, ' Orange ': 2}

By sorting to generate an ordered dictionary, there are several ways

Collections. Ordereddict (Sorted (D.items (), key = Lambda t:t[0))

Or

Collections. Ordereddict (Sorted (D.items (), key = Lambda t:t[1))

Or

Collections. Ordereddict (Sorted (D.items (), key = Lambda T:len (t[0)))