ETL & PYTHON LEARNING WITH ME
Monday, 30 March 2026
Sunday, 29 March 2026
For Loop In Python zero to Hero
For Loop In Python zero to Hero
numbers = [1, 2, 3, 4, 5]
hear Code
for number in numbers:
print(number)
#numbers is the sequence, which in this case is a defined list of numbers
#number is the loop variable that takes each value from the list, one at a time.
#print(number) is a statement in the code block that gets executed for each item in the list
number=int(input("Enter a number: "))
up_to=int(input("Enter a number: "))
for i in range(1, up_to):
print(f"{number} x {i} = {number * i}")
Statements: break and continue with for loops
The break statement allows you to exit the loop before it is completed. When the break statement is executed, the loop terminates immediately, and the program continues with the next statement following the loop.
The continue statement allows skipping the current iteration of a loop and proceeding to the next iteration. When the continue statement is encountered, the next iteration begins
items = ['apple', 'banana', 'cherry', 'date', 'elderberry']
search_item = 'cherr'
for item in items:
if item == search_item:
print(f'Found {search_item}!')
break
# Optional else clause
else:
print(f'{search_item} not found.')
=======================================================
items1 = ['apple', 'banana', 'cherry', 'lemon', 'elderberry']
for items in items1:
if 'a' in items:
continue
print(items)
================================================
In Python, enumerate() is a built-in function that adds a counter to an iterated item and returns it as an enumerated object. This can be especially useful for looping over a list, or any other item where both the index and the value of each item are needed.
As a developer, you can use these functions to make your code more readable and concise by eliminating the need to manually manage counter-variables. They also help reduce the risk of errors that can occur when manually incrementing a counter.
Here’s a simple example to illustrate how enumerate() can be used in a for loop:
# List of fruits
fruits = ['apple', 'banana', 'cherry']
# Using enumerate to get index and value
for index, fruit in enumerate(fruits, start=0 ):
print(f"{index}: {fruit}")
===============================================
Real time Usage:=
In the following loop example, you can use a loop to automate processing files. The following loop scans a directory, separates files from folders, and provides a list of all the files inside with their local path.
import os
directory = '/path/to/directory'
# Iterate over all files in the directory
for filename in os.listdir(directory):
file_path = os.path.join(directory, filename)
if os.path.isfile(file_path):
print(f'File: {filename, file_path}')
/path/to/directory is a placeholder to be replaced with the local path for the directory to be processed.
os.listdir(directory) lists all the entries in the specified directory.
os.path.join(directory, filename) constructs the full path to the file.
os.path.isfile(file_path) checks if the path is a file (and not a directory).
Knowing the exact location of files helps create precise backups and restore them when needed.
Pattern Prints in For loop
:#Pyramid Pattern (Important 🔥)
n = 5
for i in range(1, n+1):
print(" " * (n-i) + "*" * (2*i-1))
Output:-
*
***
*****
*******
*********
Pprint & Pformat in Python
If you import the pprint module into your programs, you’ll have access to the pprint() and pformat() functions that will “pretty print” a dictionary’svalues. This is helpful when you want a cleaner display of the items in a dictionary than what print() provides.
import pprint
message = "It was a bright cold day in April, and the clocks were striking thirteen."
count = {}
for character in message:
count.setdefault(character, 0)
count[character] = count[character] + 1
pprint.pprint(count)
The pprint.pprint() function is especially helpful when the dictionary itself contains nested lists or dictionaries. If you want to obtain the prettified text as a string value instead of displaying it on the screen, call pprint.pformat() instead. These two lines are equivalent to each other:
Friday, 20 March 2026
Deep in Python list
Most Important in Python(0-Z)
1.What is List.
Explain in Detail
The list class is a fundamental built-in
data type in Python
Ø Ordered:
They contain elements or items that are sequentially arranged according to
their specific insertion order.
Ø Zero-based:
They allow you to access their elements by indices that start from zero.
Ø Mutable:
They support in-place mutations or changes to their contained elements.
Ø Heterogeneous:
They can store objects of different types.
Ø Growable
and dynamic: They can grow or shrink dynamically,
which means that they support the addition, insertion, and removal of elements.
Ø Nestable:
They can contain other lists, so you can have lists of lists.
Ø Iterable:
They support iteration, so you can traverse them using a loop or comprehension
while you perform operations on each of their elements.
Ø Sliceable:
They support slicing operations, meaning that you can extract a series of
elements from them.
Ø Combinable:
They support concatenation operations, so you can combine two or more lists
using the concatenation operators.
In Python, lists are
ordered, which means that they keep their elements in the order of insertion
Ex: a
= [1, 2, 3, 4]
shopping = ["Milk", "Eggs", "Bread"]
list_name = [item1, item2, item3]
List is Mutable (VERY
IMPORTANT)
👉 You can modify list after creation
Ex:-
Indexing (in List Access
Elements):-
You can access an
individual object in a list by its position or index in the sequence. Indices
start from zero:
Synatx :list_object[index]
Ex:list[0] – acess First
Element in List
Type in Command Each below:-
course=["P","Y","T","H","O","N"]
print(course)
#Access First element in List
print("Access First element in List",course[0])
#Access last element in List
print("Access last element in List",course[-1])
#Above statement i don't know string elements that y use this one
print("Access last element in List",course[5])
#Above statement i know string elements
that y use this one
print("Access last using len function element in List",course[len(course)-1])
#aceess First two elements from list
print("Access last element in List",course[0,1]) --error Beasuce
Index not work
Slicling:-
Retrieving Multiple
Items From a List: Slicing
Syntax:- list_object[start:stop:step]
The [start:stop:step] part
of this construct is known as the slicing operator. Its syntax consists of
a pair of square brackets and three optional indices, start, stop,
and step. The second colon is optional. You typically use it only in those
cases where you need a step value different from 1.
- start specifies
the index at which you want to start the slicing. The resulting slice
includes the item at this index.
- stop specifies
the index at which you want the slicing to stop extracting items. The
resulting slice doesn’t include the item at this index.
- step provides
an integer value representing how many items the slicing will skip on each
step. The resulting slice won’t include the skipped items.
Index Default
Value
start 0
stop len(list_object)
step 1
Example:
letters = ["A",
"a", "B", "b", "C", "c", "D",
"d"]
I want Upper case letter From List
Index start with hear à 0
Stop hear d(Means 8)
Step 2 counter
upper_letters = letters[0::2]
–smart way
letters = ["A", "a", "B",
"b", "C", "c", "D", "d"]
uppercase=letters[0:8:2] --Understanding
Way this also give same result
print(uppercase)
Home work Lower Case
you Can try :
Pro Level:-
digits = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
#0 to 5 from list
print(digits[0:4]) # Res [0, 1, 2, 3]
print(digits[:4]) # Res [0, 1, 2, 3]
print(digits[-4:]) #res [6, 7, 8, 9]
print(digits[0:len(digits):2]) #res [0, 2, 4, 6, 8]
course=["P","Y","T","H","O","N"]
print(course[::-1]) # res ['N', 'O', 'H', 'T', 'Y', 'P']--revse String
To change the value of a given element in a list,
you can use the following syntax:
list_object[index] = new_value
In Python, you’ll have
two kinds of mechanisms to create copies of an existing list. You can create
either:
1.
A shallow copy
2.
A deep copy
Both types of copies
have specific characteristics that will directly impact their behaviour. In the
following sections, you’ll learn how to create shallow and deep copies of
existing lists in Python. First, you’ll take a glance at aliases, a
related concept that can cause some confusion and lead to issues and bugs.
Methods in list:
List Methods
Let's look at different
list methods in Python:
- append():
Adds an element to the end of the list.
Syntax:
list_name.append(element)
- copy():
Returns a shallow copy of the list.
Syntax: list_name.copy()
- clear():
Removes all elements from the list.
Syntax:
list_name.clear()
- count():
Returns the number of times a specified element appears in the list.
Syntax:
list_name.count(element)
- extend():
Adds elements from another list to the end of the current list.
Syntax: list_name.extend(iterable)
- index():
Returns the index of the first occurrence of a specified element.
Syntax:
list_name.index(element)
- insert():
Inserts an element at a specified position.
Syntax:
list_name.insert(index, element)
- pop():
Removes and returns the element at the specified position (or the last
element if no index is specified).
Syntax:
list_name.pop(index)
- remove():
Removes the first occurrence of a specified element.
Syntax:
list_name.remove(element)
- reverse():
Reverses the order of the elements in the list.
Syntax: list_name.reverse()
- sort(): Sorts the list in ascending
order (by default).
Syntax:
list_name.sort(key=None, reverse=False)
Max
, Min,and there or more find your self map filter alos those this your home work
Tuesday, 17 March 2026
Python list Interview Q&A
#----------------List Interview Question For Zero to Adv Level--------
# Reverse a list
number=[10,30,20,40,60,90,80,100]
# using sort and reverse keyword we can use
number.sort(reverse=True)
print(number) # result [100, 90, 80, 60, 40, 30, 20, 10]
number1=[10,30,20,40,60,90,80,100]
#without Sort and reverse key word
print(number1[::-1]) #result [100, 80, 90, 60, 40, 20, 30, 10]
#2. Find largest & smallest
number2=[10,30,20,40,60,90,80,100]
print(max(number2)) # Max Number is 100
print(min(number2)) # Min Number is 10
print(sum(number2)) # Sum of Number is 430
#3.Count occurrences
number2=[10,30,20,40,20,20,20,60,90,80,100]
print(number2.count(20)) # Result is 4
#4.Remove duplicates
print(list(set(number2))) #[100, 40, 10, 80, 20, 90, 60, 30]
#5 Second_largest number in list
L1=list(set(number2)) # Remove Duplicates
L1.sort() # sort the List
print(L1[-2]) # Find the Second_Highest Number
mylist = ['apple', 'banana', 'cherry']
mylist[1:2] = ['kiwi', 'mango']
print(mylist)
print(mylist[2])
Python List Full Infromation with Interview questions
#LIST --List one of the data type in python
#A List is a collection of items stored in a single variable.
#list can store multiple values with comma speciation
#list we can identify begins with an opening square bracket and
#ends with a closing square bracket, []
#A list value looks like this: ['cat', 'bat', 'rat', 'elephant'].
# list is Ordered,Mutable (changeable),Allow duplicates ,Can store different data types
#
animals=["cat","rat","Cow","Hen","horse","dog"]
print("Name of the animals Is",animals)
#in List data type we can store String values ,Int values ,flote values anything
animals_digits=["cat","0","rat","1","Cow","2","Hen","3","horse","4","dog","5"]
print("Name of the animals Is",animals_digits)
#Just as an index can get a single value from a list,
#List value Index --> it will Index first value from list
print(animals_digits[0])
print(animals_digits[1]) #it will Index 2 value from list
print(animals_digits[2]) #it will Index 3 value from list
print(animals_digits[-1]) #it will Negative Index Last value from list
print(animals_digits[-2])
#a slice can get several values from a list, in the form of a new list
print(animals_digits[0:4]) # Get 0,1,2,3 values from List # means 0-cat,1-0,2-rat,3-1
text = "HELLO"
print(text[1]) # E
print(text[1:2]) # E (but type is different!)
text = "PYTHON"
print(text[::2]) # Result is PTO Means Step = 2 (skip one)
Blak = "Mahen"
print(Blak[1:10])
#-------------------------------------------------
text = "HELLO"
print(text[1:2] == text[1]) # Result should be True
# Both are 'E', but types conceptually differ (still equal)
#---------------------------------------------------
nums = [10, 20, 30, 40]
print(nums[-3:-1])
#While Slicing start included, stop excluded
#Changing the Values in List
nums[0]=200 # Old Nums [10, 20, 30, 40]
print(nums) #Result should be [200, 20, 30, 40]
#List Concatenation(+) and List Replication(*)
value=[1, 2, 3] + ['A', 'B', 'C']
print(value) # Result is:-[1, 2, 3, 'A', 'B', 'C']
value=[1,2,3]*2
print(value) # Result Is:[1, 2, 3, 1, 2, 3]
#Removing Values from Lists with del Statements
del value[1] # Result Is:[1, 2, 3, 1, 2, 3]
print(value) #Result [1, 3, 1, 2, 3]
#Adding Values to Lists with the append() and insert() Methods
# sy : string.append(value)
s1=[1,2,3,'python','java']
s1.append('C++')
print(s1) #[1, 2, 3, 'python', 'java', 'C++']
#Insert Method SY: Insert(index,object)
str=[1,2,3,'python','java']
str.insert(2,'C') #[1, 2, 'C', 3, 'python', 'java']
print(str)
#Removing Values from Lists with remove()
str1=[1,2,3,'python','java']
str1.remove(2)
print(str1) # result [1, 3, 'python', 'java']
#Sorting the Values in a List with the sort() Method
str2=[0,5,13,9,6,20,15]
str2.sort() # result [0, 5, 6, 9, 13, 15, 20]
print(str2)
str2.sort(reverse=True) # result [20, 15, 13, 9, 6, 5, 0]
print(str2)
str3=[1, 3, 2, 4, 'Alice', 'Bob']
#str3.sort()
print(str3) #TypeError: '<' not supported between instances of 'str' and 'int'
#A list value is a mutable data type: It can have values added, removed, or changed.
#List Copy
l1=str1.copy() #str1 copy into l1
print(l1)
#========== real Time Interview question ===============
#Find the largest Number in given LIST
Numbers=[10,20,30,50,60] # Largest Number is 60
print(max(Numbers)) #->60
#Find the second-largest number in List
Numbers=[10,20,70,50,90,15,20,80,20,25,100]
Numbers.sort(reverse=False)
print(Numbers[-2]) # result 90
# Remove Duplicates in Given List
Number1=[10,20,70,50,90,15,20,80,20,25,100]
unique=list(set(Number1))
print(unique) #-->[100, 70, 10, 15, 80, 50, 20, 25, 90]
# List Unpacking
a, b, c = [10, 20, 30]
print(a, b, c) #
print(a+b)
print(a)
#Reveses list Using Reverse keyword without using reverse key word
nums = [1,2,3,4]
nums.sort(reverse=True)
print(nums)
print(nums[::1])#-Result [4, 3, 2, 1]
Even and Odd Value Find in python along examption handling
try:
number = int(input("Enter a number: "))
if number % 2 == 0:
print("Even")
else:
print("Odd")
except ValueError:
print("Invalid input! Please enter a valid number.")
Print the Sum of Number in range in python
#Print the Sum of Number in range #0,1,2,3,4,5,6,7,8,9,10 #0+1+2+3+4+5+6+7+8+9+10=55 num=int(input("Enter a number: ")) print(sum...
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