12 essential code snippets you must know about Python programming

1. Regular expressions

Regular expressions are the best technology in Python for matching patterns, searching and replacing strings, validating strings, etc. Now you don't need to use loops and lists for this kind of work.

Check out the following regular expression snippet code example for validating email format:

# Regular Expression Check Mail
import re
def Check_Mail(email):
 pattern = re.compile(r'([A-Za-z0-9]+[.-_])*[A-Za-z0-9]+@[A-Za-z0-9-]+(.[A-Z|a-z]{2,})+')
 if re.fullmatch(pattern, email):
 print("valid")
 else:
 print("Invalid")
Check_Mail("codedev101@gmail.com") #valid
Check_Mail("codedev101-haider@uni.edu")#Invalid
Check_Mail("code-101-work@my.net") # Invalid

2, Pro Slicing

This simple code snippet will Helps you slice your lists like a pro. Check out the sample code below:

# Pro Slicing
# list[start:end:step]
mylist = [1, 2, 3, 5, 5, 6, 7, 8, 9, 12]
mail ="codedev-medium@example.com"
print(mylist[4:-3]) # 5 6 7
print(mail[8 : 14]) # medium

3. Swap without Temp

Are you using the Temp variable to swap two data, as in Python you don't need to use it? In this code snippet, I will share with you how to swap two data variables without using temp.

View the code below:

# Swap without Temp
i = 134
j = 431
[i, j] = [j, i]
print(i) #431
print(j) #134

4. Magic of F-string

We may use the format() method or the "%" method to Variables in the format string. This code will introduce you to F-strings, which are much better than the other format.

Look at the sample code below:

# Magic of f-String
# Normal Method
name = "Codedev"
lang = "Python"
data = "{} is writing article on {}".format(name, lang)
print(data)
# Pro Method with f-string
data = f"{name} is writing article on {lang}"
print(data

5. Get the index

Now you no longer need a Loop to find the index of a specific element. You can do this using the index() method on the list.

Look at the code below:

# Get Index
x = [10 ,20, 30, 40, 50]
print(x.index(10)) # 0
print(x.index(30)) # 4
print(x.index(50)) # 2

6. Sorted list based on Another List

This code snippet will show you how to sort the list based on another list Sort the list. This snippet comes very handy when you need to sort based on the desired position.

# Sort List based on another List
list1 =["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m"]
list2 = [ 0, 1, 1, 1, 2, 2, 0, 1, 1, 3, 4]
C = [x for _, x in sorted(zip(list2, list1), key=lambda pair: pair[0])]
print(C) # ['a', 'g', 'b', 'c', 'd', 'h', 'i', 'e', 'f', 'j', 'k']

7. Reversing Dictionaries

Now you don’t need to loop to reverse any dictionary. This snippet code will reverse the dictionary the second time the snippet code is tried.

# Invert the Dictionary
def Invert_Dictionary(data):
 return{value: key for key, value in data.items()}
data = {"A": 1, "B":2, "C": 3}
invert = Invert_Dictionary(data)
print(invert) # {1: 'A', 2: 'B', 3: 'C'}

8. Multi-threading

Multi-threading will help you run Python functions in parallel at the same time. Suppose you want to execute 5 functions simultaneously without waiting for each function to complete.

View the following code snippet:

# Multi-threading
import threading
def func(num):
 for x in range(num):
 print(x)
if __name__ == "__main__":
 t1 = threading.Thread(target=func, args=(10,))
 t2 = threading.Thread(target=func, args=(20,))
 t1.start()
 t2.start()
 t1.join()
 t2.join()

9. The element that appears the most in the list

This code snippet will simply count the number of occurrences in the list most elements. I've shown two ways to do this.

Check it out below:

# Element Occur most in List
from collections import Counter
mylst = ["a", "a", "b", "c", "a", "b","b", "c", "d", "a"]
# Method 1
def occur_most1(mylst):
 return max(set(mylst), key=mylst.count)
print(occur_most1(mylst)) # a
# Method 2
# Much Faster then Method 1
def occur_most2(mylst):
 data = Counter(mylst)
 return data.most_common(1)[0][0]
print(occur_most2(mylst)) # a

10. Split line

Have a raw text in progressive format and want to split it into several lines . This code snippet will solve your problem in just a second.

# Split lines
data1 = """Hello to
Python"""
data2 = """Programming
Langauges"""
print(data1.split("n")) # ['Hello to', 'Python']
print(data2.split("n")) # ['Programming', ' Langauges']

11. Mapping List to Dictionary

This code snippet will help you convert any two lists into dictionary format. To understand how it works, take a look at the code below:

# Map List into Dictionary
def Convert_to_Dict(k, v):
 return dict(zip(k, v))
k = ["a", "b", "c", "d", "e"]
v = [1, 2, 3, 4, 5]
print(Convert_to_Dict(k, v)) # {'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5}

12. Parsing the spreadsheet

Now you don’t need Pandas or any other external Python package to parse the spreadsheet . Python has a built-in CSV module and this code will show you how to use it.

# Parse Spreadsheet
import csv
#Reading
with open("test.csv", "r") as file:
 csv_reader = csv.reader(file)
 for row in csv_reader:
 print(row)
file.close()
#Writing
header = ["ID", "Languages"]
csv_data = [234, "Python", 344, "JavaScript", 567, "Dart"]
with open("test2.csv", 'w', newline="") as file:
 csv_writer = csv.writer(file)
 csv_writer.writerow(header)
 csv_writer.writerows(csv_data)

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