![]() ![]() Then build the undecorate expression (which is usually as simple as what I've shown here). Build the "decorate" expression or function. Usually you should built up such code iteratively, in the interpreter using small data samples. myDict.keys() is, of course, a method of Python dictionaries which returns a list of all valid keys in whatever order the underlying implementation chooses - presumably a simple iteration over the hashes.Ī more verbose way of doing this might be easier to read: temp = list() The inner comprehension is creating a set of tuples, your desired sorting key (the 3rd element of the list) and the dictionary's key corresponding to the sorting key. that's a list comprehension doing the undecorate from the sorted list of tuples which is being returned by the inner list comprehension. In this case you should be able to use something like: for y in sorted(, x) for x in myDict.keys()])] So it's usually far better to iterate over the data creating data structures which can be passed to the default sort routines. ![]() sort() method is that Python's built-in default sorting code (compiled C in the normal C Python) is very fast and efficient in the default case, but much, much slower when it has to call Python object code many, many times in the non-default case. The reason this is generally preferred over passing comparison function to the. sort() method on that list (or, in more recent versions of Python simply wrap your decoration in a called to the sorted() built-in function). In this idiom you create a temporary list which contains tuples of your key(s) followed by your original data elements, then call the normal. The preferred Python pattern (idiom) for sorting by any alternative criterium is called "decorate-sort-undecorate" (DSU). However, you can create an index of the keys which can be sorted in any order you like. Insert into ex_dict values('item1', 7, 1, 9) Īs John Machlin said you can't actually sort a Python dictionary. If you are going to be doing extract/sort/process often on large data sets, you might like to consider something like this, using the Python-supplied sqlite3 module: create table ex_dict (k text primary key, v0 int, v1 int, v2 int) you may like to investigate using named tuples instead of lists see named tuple factory "the third item in the list" smells like "the third item in a tuple" to me, and "e" just smells :-). Using list.sort () Lists have only one special method: bash list.sort (, keyNone, reverseFalse) By default, sort () performs an A-Z-style sort, with lower values on the left. By the way, the solution that uses "key" instead You can use different function to sort different data types in Python.
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