Improve your Python with our efficient tips and tricks.
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Tip and Trick 1: How to measure the time elapsed to execute your code in Python
Let’s say you want to calculate the time taken to complete the execution of your code. Using a time module, You can calculate the time taken to execute your code.
import time
startTime = time.time()
# write your code or functions calls
endTime = time.time()
totalTime = endTime - startTime
print("Total time required to execute code is= ", totalTime)Tip and Trick 2: Get the difference between the two Lists
Let’s say you have the following two lists.
list1 = ['Scott', 'Eric', 'Kelly', 'Emma', 'Smith']
list2 = ['Scott', 'Eric', 'Kelly']If you want to create a third list from the first list which isn’t present in the second list. So you want output like this list3 = [ 'Emma', 'Smith]
Let see the best way to do this without looping and checking. To get all the differences you have to use the set’s symmetric_difference operation.
list1 = ['Scott', 'Eric', 'Kelly', 'Emma', 'Smith']
list2 = ['Scott', 'Eric', 'Kelly']
set1 = set(list1)
set2 = set(list2)
list3 = list(set1.symmetric_difference(set2))
print(list3)Tip and Trick 3: Calculate memory is being used by an object in Python
whenever you use any data structure(such as a list or dictionary or any object) to store values or records.
It is good practice to check how much memory your data structure uses.
Use the sys.getsizeof function defined in the sys module to get the memory used by built-in objects. sys.getsizeof(object[, default]) return the size of an object in bytes.
import sys
list1 = ['Scott', 'Eric', 'Kelly', 'Emma', 'Smith']
print("size of list = ",sys.getsizeof(list1))
name = 'pynative.com'
print("size of name = ",sys.getsizeof(name))Output:
('size of list = ', 112)
('size of name = ', 49)
Note: The sys.getsizeof doesn’t return the correct value for third-party objects or user defines objects.
Tip and Trick 4: Removing duplicates items from a list
Most of the time we wanted to remove or find the duplicate item from the list. Let see how to delete duplicate from a list. The best approach is to convert a list into a set. Sets are unordered data-structure of unique values and don’t allow copies.
listNumbers = [20, 22, 24, 26, 28, 28, 20, 30, 24]
print("Original= ", listNumbers)
listNumbers = list(set(listNumbers))
print("After removing duplicate= ", listNumbers)Output:
'Original= ', [20, 22, 24, 26, 28, 28, 20, 30, 24] 'After removing duplicate= ', [20, 22, 24, 26, 28, 30]
Tip and Trick 5: Find if all elements in a list are identical
Count the occurrence of a first element. If it is the same as the length of a list then it is clear that all elements are the same.
listOne = [20, 20, 20, 20]
print("All element are duplicate in listOne", listOne.count(listOne[0]) == len(listOne))
listTwo = [20, 20, 20, 50]
print("All element are duplicate in listTwo", listTwo.count(listTwo[0]) == len(listTwo))Output:
'All element are duplicate in listOne', True 'All element are duplicate in listTwo', False
Tip and Trick 6: How to efficiently compare two unordered lists
Let say you have two lists that contain the same elements but elements order is different in both the list. For example,
one = [33, 22, 11, 44, 55]
two = [22, 11, 44, 55, 33]The above two lists contains the same element only their order is different. Let see how we can find two lists are identical.
- We can use
collections.Countermethod if our object is hashable. - We can use
sorted()if objects are orderable.
from collections import Counter
one = [33, 22, 11, 44, 55]
two = [22, 11, 44, 55, 33]
print("is two list are b equal", Counter(one) == Counter(two))Output:
'is two list areb equal', True
Tip and Trick 7: How to check if all elements in a list are unique
Let say you want to check if the list contains all unique elements or not.
def isUnique(item):
tempSet = set()
return not any(i in tempSet or tempSet.add(i) for i in item)
listOne = [123, 345, 456, 23, 567]
print("All List elemtnts are Unique ", isUnique(listOne))
listTwo = [123, 345, 567, 23, 567]
print("All List elemtnts are Unique ", isUnique(listTwo))Output:
All List elemtnts are Unique True All List elemtnts are Unique False
Tip and Trick 8: Convert Byte to String
To convert the byte to string we can decode the bytes object to produce a string. You can decode in the charset you want.
byteVar = b"pynative"
str = str(byteVar.decode("utf-8"))
print("Byte to string is" , str )Output:
Byte to string is pynative
Tip and Trick 8: Use enumerate
Use enumerate() function when you want to access the list element and also want to keep track of the list items’ indices.
listOne = [123, 345, 456, 23]
print("Using enumerate")
for index, element in enumerate(listOne):
print("Index [", index,"]", "Value", element)Output:
Using enumerate Index [ 0 ] Value 123 Index [ 1 ] Value 345 Index [ 2 ] Value 456 Index [ 3 ] Value 23
Tip and Trick 9: Merge two dictionaries in a single expression
For example, let say you have the following two dictionaries.
currentEmployee = {1: 'Scott', 2: "Eric", 3:"Kelly"}
formerEmployee = {2: 'Eric', 4: "Emma"}And you want these two dictionaries merged. Let see how to do this.
In Python 3.5 and above:
currentEmployee = {1: 'Scott', 2: "Eric", 3:"Kelly"}
formerEmployee = {2: 'Eric', 4: "Emma"}
allEmployee = {**currentEmployee, **formerEmployee}
print(allEmployee)In Python 2, or 3.4 and lower
currentEmployee = {1: 'Scott', 2: "Eric", 3:"Kelly"}
formerEmployee = {2: 'Eric', 4: "Emma"}
def merge_dicts(dictOne, dictTwo):
dictThree = dictOne.copy()
dictThree.update(dictTwo)
return dictThree
print(merge_dicts(currentEmployee, formerEmployee))
Tip and Trick 10: Convert two lists into a dictionary
Let say you have two lists, and one list contains keys and the second contains values. Let see how can we convert those two lists into a single dictionary. Using the zip function, we can do this.
ItemId = [54, 65, 76]
names = ["Hard Disk", "Laptop", "RAM"]
itemDictionary = dict(zip(ItemId, names))
print(itemDictionary)Tip and Trick 11: Convert hex string, String to int
hexNumber = "0xfde"
stringNumber="34"
print("Hext toint", int(hexNumber, 0))
print("String to int", int(stringNumber, 0))Tip and Trick 12: Format a decimal to always show 2 decimal places
Let say you want to display any float number with 2 decimal places. For example 73.4 as 73.40 and 288.5400 as 88.54.
number= 88.2345
print('{0:.2f}'.format(number))Tip and Trick 13: Return multiple values from a function
def multiplication_Division(num1, num2):
return num1*num2, num2/num1
product, division = multiplication_Division(10, 20)
print("Product", product, "Division", division)Tip and Trick 14: The efficient way to check if a value exists in a NumPy array
This solution is handy when you have a sizeable NumPy array.
import numpy
arraySample = numpy.array([[1, 2], [3, 4], [4, 6], [7, 8]])
if value in arraySample[:, col_num]:
print(value)
