pavanbaddi
Posted on May 1, 2020
In Python, Sorting is systematically arranging the data as per the given criteria. These have a lot of applications and you will be studying this in-depth.
Examples:
*) Arranging student roll numbers in ascending order
*) Displaying the products which have high sales etc
Sorting lists
Let us start with a simple example of list sorting by numbers. We'll be using a built-in method under list sort() method to get a result. Syntax
newlist.sort(optional parameters)
Below optional parameters
Option Name -- Values -- Default Value
reverse : -- True or False -- False
key -- NA -- len() method to sort on bases on length of string,custom user defined function can also be used |
Sorting numbers in Ascending order
a=[
9,6,8,2,1,7,3
]
a.sort()
print(a)
#PYTHON OUTPUT
[1, 2, 3, 6, 7, 8, 9]
Sorting numbers in Descending order
a=[
9,6,8,2,1,7,3
]
a.sort(reverse=True)
print(a)
#PYTHON OUTPUT
[9, 8, 7, 6, 3, 2, 1]
Sorting years with sort() using user defined function
def myfunc(e):
return e
a=[
2018,2015,2017,2000,2013,2011
]
a.sort(key=myfunc)
print(a)
#PYTHON OUTPUT
[2000, 2011, 2013, 2015, 2017, 2018]
Sorting names by alphabets
names = [
'John','Nancy','Amber','Peter','Bane'
]
names.sort()
print(names)#prints names in alphabetical ascending order
names.sort(reverse=True)
print(names)#prints names in alphabetical descending order
#PYTHON OUTPUT
['Amber', 'Bane', 'John', 'Nancy', 'Peter']
['Peter', 'Nancy', 'John', 'Bane', 'Amber']
Note : sort() method only sorts on list and returns None. To sort on non-list array use sorted() method.
Sorting Tuples
Sorting using sorted() method
d = (
5,2,6,1,9
)
print(sorted(d))
print(sorted(d,reverse=True))
#PYTHON OUTPUT
[1, 2, 5, 6, 9]
[9, 6, 5, 2, 1]
Sorting Dictionaries
Sorting Keys of the dictionary Below we have created a dictionary which has names in key and value. To only order keys of dictionary use d.keys() method this will return keys of that dictionary. Calling reverse=True attribute inside sorted() method will return sorted list in reverse order.
d={
0:'Amber',
1:'John',
2:'Kiran',
3:'Rakesh',
4:'Yogesh',
}
print(sorted(d.keys())) #This will order keys of dictionary in Ascending Order
print(sorted(d.keys(),reverse=True)) # Calling reverse attribute with value True will print the keys of dictionary in Descending Order
#PYTHON OUTPUT
[0, 1, 2, 3, 4]
[4, 3, 2, 1, 0]
Sorting Values in the dictionary Here we'll be using the same method as above except insisted on calling d.keys(). We'll call d.values() method which returns values of dictionary.
d={
0:'Amber',
1:'John',
2:'Kiran',
3:'Rakesh',
4:'Yogesh',
}
print(sorted(d.values())) #This will order values of dictonary in Ascending Order
print(sorted(d.values(),reverse=True)) # Calling reverse attribute with value True will print the values of dictonary in Descending Order
Advance Dictionary Sorting
In reality, there will be many cases where dictionary is multi-dimensional and need the be order. So in this tutorial, we'll be covering most of the complex multi-dimensional dict and sort them in order. Sorting dictionary by user age.
d = {
0 : {
'username' : 'Jane154',
'fname' : 'Jane',
'age' : 22,
},
1 : {
'username' : 'Humayun12',
'fname' : 'Humayun',
'age' : 16,
},
2 : {
'username' : 'Rakesh45',
'fname' : 'Rakesh',
'age' : 29,
},
3 : {
'username' : 'Kimmy123',
'fname' : 'Kimmy',
'age' : 12,
},
}
def sortByAge(e):
return e[1]['age']
print(sorted(d.items(),key=sortByAge))
print("\n\nSorting age in reverse order with tuple inside list \n\n")
print(sorted(d.items(),key=sortByAge,reverse=True))
print("\n\nSorting age in reverse order and this will return a dictionary \n")
print(dict(sorted(d.items(),key=sortByAge,reverse=True)))
#PYTHON OUTPUT
[(3, {'username': 'Kimmy123', 'fname': 'Kimmy', 'age': 12}), (1, {'username': 'Humayun12', 'fname': 'Humayun', 'age': 16}), (0, {'username': 'Jane154', 'fname': 'Jane', 'age': 22}), (2, {'username': 'Rakesh45', 'fname': 'Rakesh', 'age':29})]
Sorting age in reverse order
[(2, {'username': 'Rakesh45', 'fname': 'Rakesh', 'age': 29}), (0, {'username':'Jane154', 'fname': 'Jane', 'age': 22}), (1, {'username': 'Humayun12', 'fname': 'Humayun', 'age': 16}), (3, {'username': 'Kimmy123', 'fname': 'Kimmy', 'age':12})]
{2: {'username': 'Rakesh45', 'fname': 'Rakesh', 'age': 29}, 0: {'username': 'Jane154', 'fname': 'Jane', 'age': 22}, 1: {'username': 'Humayun12', 'fname': 'Humayun', 'age': 16}, 3: {'username': 'Kimmy123', 'fname': 'Kimmy', 'age': 12}}
Note: Dictionaries are unordered and unsorted collection on data. so like lists they don't have sort() method. But bypassing dictionary in sorted() method will return Tuple inside list in sorted order.
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Posted on May 1, 2020
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