Let's glide through all the basic concepts in Python :
- To give single or multi-line comment use:
#single line comment
""" multi-line
comment"""
- We can declare variables directly in Python without putting any data type unlike other languages like C/C++.
x = 8
y = "variable"
print(x) # to print a statement
print(y)
a , b = "Hello" , "World" # to assign values in single line
print(a)
print(b)
- To get the data type of any object:
x = 8
print(type(x))
- Basic operations in Python:
a = 4
b = 9
print(a+b) # addition
print(a-b) # subtraction
print(a/b) # division
print(a*b) # multiplication
print(a**b) # exponentiation
- The basic data structures in Python are:
-> List: An ordered collection that is changeable and allows duplicate members.
-> Tuple: An ordered collection that is unchangeable and allows duplicate members.
-> Set: An unordered and unindexed collection doesn't allow duplicate members.
-> Dictionary: An unordered collection that is changeable and indexed. Also, it doesn't allow duplicate members.
a = ["Hello", "World", "!"] #List
b = ("Hello", "World", "!") #Tuple
c = {"Hello", "World", "!"} #Set
d = {"name" : "Suraj", "age" : 18, "location": "India"} #Dict
- To understand the data structures in detail:
1) List:
#To print items in list using for loop:
this_list = ["A", "B", "C"]
for x in this_list: # don't forget indentation in python codes
print(x)
#To check if item is present in the list:
this_list = ["A", "B", "C"]
if "D" in this_list :
print("present")
#Note: You may add print statements to view your results.
# Use the append() to append an item in the list:
this_list = ["A", "B", "C"]
this_list.append("D")
#To insert item at a specified index in the list:
this_list = ["A", "B", "C"]
this_list.insert(1, "D")
#To remove a specific item from the list:
this_list = ["A", "B", "C"]
this_list.remove("B")
#To pop last item from the list:
this_list = ["A", "B", "C"]
this_list.pop()
#To removes an item from a specified index
this_list = ["A", "B", "C"]
del this_list[1]
#To clear the entire list
this_list = ["A", "B", "C"]
this_list .clear()
#To find length of the entire list
this_list = ["A", "B", "C"]
len(this_list)
#To join two lists
this_list = ["A", "B", "C"]
another_list = ["D", 3, 4]
result_list = this_list + another_list
# result_list would have elements from both list
#To convert List to Tuple:
this_list = ["A", "B", "C"]
tuple(this_list )
#To slice List:
this_list = ["A", "B", "C"]
this_list[3:8] # slicing the list
2) Tuple:
# To print items in Tuple:
this_tuple = ("A", "B", "C")
for x in this_tuple:
print(x)
#To find length of Tuple:
this_tuple = ("A", "B", "C")
print(len(this_tuple))
# Convert
this_tuple = ("A", "B", "C")
list(this_tuple) #converting tuple to list
#To find type of Tuple:
this_tuple = ("A", "B", "C")
print(type(this_tuple))
# To slice Tuples
this_tuple = ("A", "B", "C", "D" , "E")
print(this_tuple[1:]) # to print items from index 1
# to print items starting from index 2 to index 3 (i.e 4-1)
print(this_tuple[2:4])
print(this_tuple[::-1]) # to print in reverse manner
#To delete a tuple
this_tuple = ("A", "B", "C")
del this_tuple
3) Set:
# To print items in Set:
this_set = {"A", "B", "C"}
for x in thisset:
print(x)
#To add items in set :
this_set = {"A", "B", "C"}
this_set .add("D")
#To update set :
this_set = {"A", "B", "C"}
this_set .update([1,2,3])
#To remove an item from a set:
this_set = {"A", "B", "C"}
this_set .remove("C")
#To pop item from set
this_set = {"A", "B", "C"}
this_set .pop()
#To clear everything from the set:
this_set = {"A", "B", "C"}
this_set.clear()
#To add items form one set to another
this_set = {"A", "B", "C"}
another_set= {1, 2, 3}
this_set.update(another_set)
#Note: every time you run the command the items would be #shuffled which justify that items in set are unordered.
#Operations in Sets:
this_set = {1,2,3,4,5}
another_set= {3,4,5,6,7}
print(this_set|another_set) #Union
print(this_set - another_set) #Difference
print(this_set & another_set) #Intersection
4) Dictionary:
#To print a Dictionary:
# items are in key:value pairs
this_dict = {
"Name": "Suraj",
"Age": "18",
"Year": 2020
}
print(this_dict) # You can also use a for loop.
#Adding new index key with value:
this_dict = {"Name": "Suraj", "Age": "18", "Year": 2020}
this_dict["newItem"] = "newValue"
#To pop a value from a dictionary:
this_dict.pop("Year") #specifying key value
#To clear the Dictionary:
this_dict.clear()
#To copy items from one Dictionary to another :
this_dict = {"Name": "Suraj", "Age": "18", "Year": 2020}
another_dict = this_dict.copy()
# then print
#To delete a value from Dictionary:
this_dict = {"Name": "Suraj", "Age": "18", "Year": 2020}
del Dict["Age"]
- Characters in Python :
character = "Hello World!"
print(character[1]) # to get character at index 1
print(character[3:7]) # to get character at from index 3 to 6
#It can also be done using negative indexes
#To find the length of the character
len(character)
#Some other basic functions:
character = "Hello World!"
print(character .lower()) # to convert to lowercase
print(character .upper()) # to convert to uppercase
print(character .replace("W", "Y")) # To replace characters in it
print(character .split(",")) # returns ['Hello World!']
Logical operators in Python:
They are used to combine conditional statements.and - returns True if both statements are true . or - returns True if one of the statements is true . not - reverses the result, returns False if the result is true .Loops in Python:
#For loop
num = 0
for num in range(0, 10):
print(num) # to print numbers from the range
#While loop
while (num < 10):
num = num + 1
print(num) # to print numbers
- If-else statements in Python:
num = 0
for num in range(0, 10):
if(num<5):
print(num) # to print numbers less than 5
- Functions in Python:
def function(x):
print("Function called")
print("Value passed is ",x)
function(5)
# Now using lamda function.
# It can take any number of arguments, but can only have one #expression.
#syntax : lambda arguments : expression
function = lambda x : x*2
print("Returning a value twice the passed value:",function(10))
With this, we have slid through the basics.
Hope it's been helpful!