Some suggestions on the Python collection

1. Check if the list is empty

There is no need to call the Len method to detect if a list is empty, because an empty list evaluates to False.

if Len (mylist):     # Do something with my list Else :     # The list is empty

You can use the following method instead:

if mylist:     # Do something with my list Else :     # The list is empty

2. Get the index value of an element at the same time as the iteration list

Sometimes you need to iterate over a list and get the index value for each element. The usual practice is to:

i = 0 for in mylist:    # does something with I and element    i + = 1

A better approach would be to:

 for inch Enumerate (mylist):     # Do something with I and element    Pass

3. List sorting

Create a persons list:

class Person (object):     def __init__ (self, Age):         = for in (14, 78, 42)]

If we want to sort the list by age, we can do this:

def Get_sort_key (Element):     return Element.age  for  in sorted (persons, key=Get_sort_key):    print"age:" , Element.age

We define a function that returns the attributes that are the sort criteria. and pass this function as a parameter to the sorted function. Because this sort is common, the Python standard library already contains such a function.

 from Import Attrgetter # Attrgetter is a high-order function that can return a function  for  in sorted (persons, Key=attrgetter ('age')):    Print " Age : ", Element.age

This makes the code easier to read. When you see the Attrgetter function you will know that it is used to get a property. There are also Itemgetter and Methodcaller methods in the operator module, and I believe you can see their role at a glance.

Some suggestions on the Python collection