Method 1

※ Download: onamteci.fastdownloadportal.ru?dl&keyword=python+sort+by+two+keys&source=bandcamp.com


See for an example for strings. Recently, I get stuck with the problem of sorting by two criteria.

My advice: use lambda when appropriate and don't feel guilty about it Kent Johnson wrote: Scott David Daniels wrote: Kent Johnson wrote: In Python 2. Instead, all of the Py2. I would especially like it to be clear and simple, since I am converting a web app from using SQL to using an ORM only and so the sorting will actually be controlled by variables coming from SELECTs in a web form.

Method 1

A common idiom in programming is sorting a list. Python makes this a very simple task. Python provides a built-in sorted function that accepts an iterable type, and return a sorted list: 1. In the dictionary case, it returns a sorted list of the dictionaries keys. This is where the sorted function shines. The sorted function accepts a key as an optional named parameter. This key should be, itself, a function which accepts one parameter and will be used by the sorted function to determine a value to sort on. Leaving the respresentation like this would have made it harder for us to distinguish between different instances in the examples to come. A key function must accept a single argument and returns a value on which to base the sorting sorted will call the key function on each element of the iterable it is given, and use this return value when sorting the list. This is an important distinction. Remember, sorted will make use of the key function, calling it on each element of the iterable. Reverse Sorting The sorted function makes it easy to sort in reverse order too. Sort using attrgetter Function This time, the list returned is sorted by age, just as we expected. We specify the name of the attribute to be fetched, and attrgetter generates a function that accepts an object and return the specified attribute from that object. Advance Usage of Key in Sorted Function So far, our key functions have been simple attribute readers, but they can also compute a value to sort on. By default, the sorted function will return a list sorted in its natural sort order which is generally what we want for numbers and strings. For more information about the sorted function, visit the python official docs. Our key functions can return any value that we desire, but a lot of the time we want to sort on some attribute belonging to each element of the list. In fact, this is so often the case that Python provides a standard library function, operator. First element of I is third, last element is ranks first, the fifth element ranks 6th.. Lists in python are 0-indexed, by the way.

To sort all I needed to do was: list. Abridged, the problem was of the kind: given a text, count how often each word is encountered and display a list of the top words, sorted by decreasing frequency. Using those functions, the above examples become simpler and faster. Uses a treap for implementation and improves performance using Cython. Except as otherwise noted, the content of this page is licensed under theand code samples are licensed under the. I'd like to be able to arbitrarily sort by any combination of those in any order. Another thing is that it sorts in place, whereas sorted seems to make a copy. I used it to write a rank function, that ranks a list of classes where each object is in a group and has a score function, but you can add any list of attributes. Maintaining Sort Order Python does not provide modules like C++'s set and map data types as part of its standard library.