def square(n):
    return n * n

numbers = [1, 2, 3, 4]
squared_numbers = map(square, numbers)
print(list(squared_numbers))

[1, 4, 9, 16]

---
#Python #FunctionalProgramming #Keywords

#21. filter()
Constructs an iterator from elements of an iterable for which a function returns true.

def is_even(n):
    return n % 2 == 0

numbers = [1, 2, 3, 4, 5, 6]
even_numbers = filter(is_even, numbers)
print(list(even_numbers))

[2, 4, 6]

#22. lambda
Creates a small anonymous function.

multiply = lambda a, b: a * b
print(multiply(5, 6))

30

#23. def
Keyword used to define a function.

def greet(name):
    return f"Hello, {name}!"

print(greet("World"))

Hello, World!

#24. return
Keyword used to exit a function and return a value.

def add(a, b):
    return a + b

result = add(7, 8)
print(result)

15

#25. isinstance()
Checks if an object is an instance of a specified class.

number = 10
print(isinstance(number, int))
print(isinstance(number, str))

True
False

---
#Python #ControlFlow #Keywords

#26. if, elif, else
Used for conditional execution.

score = 85
if score >= 90:
    print("Grade A")
elif score >= 80:
    print("Grade B")
else:
    print("Grade C")

Grade B

#27. for
Used to iterate over a sequence (like a list, tuple, or string).

colors = ["red", "green", "blue"]
for color in colors:
    print(color)

red
green
blue

#28. while
Creates a loop that executes as long as a condition is true.

count = 0
while count < 3:
    print(f"Count is {count}")
    count += 1

Count is 0
Count is 1
Count is 2

#29. break
Exits the current loop.

for i in range(10):
    if i == 5:
        break
    print(i)

0
1
2
3
4

#30. continue
Skips the rest of the code inside the current loop iteration and proceeds to the next one.

for i in range(5):
    if i == 2:
        continue
    print(i)

0
1
3
4

---
#Python #StringMethods #TextManipulation

#31. .upper()
Converts a string into upper case.

message = "hello python"
print(message.upper())

HELLO PYTHON

#32. .lower()
Converts a string into lower case.

message = "HELLO PYTHON"
print(message.lower())

hello python

#33. .strip()
Removes any leading and trailing whitespace.

text = "   some space   "
print(text.strip())

some space

#34. .split()
Splits the string at the specified separator and returns a list.

sentence = "Python is fun"
words = sentence.split(' ')
print(words)

['Python', 'is', 'fun']

#35. .join()
Joins the elements of an iterable to the end of the string.

words = ['Python', 'is', 'awesome']
sentence = " ".join(words)
print(sentence)

Python is awesome

---
#Python #MoreStringMethods #Text

#36. .replace()
Returns a string where a specified value is replaced with another value.

text = "I like cats."
new_text = text.replace("cats", "dogs")
print(new_text)

I like dogs.

try:
    result = 10 / 0
except ZeroDivisionError:
    result = "You can't divide by zero!"
print(result)

You can't divide by zero!

#52. open()
Opens a file and returns a file object.

# This code creates a file named "myfile.txt"
# No direct output, but a file is created.
file = open("myfile.txt", "w") 
file.close() 
print("File created and closed.")

File created and closed.

#53. .write()
Writes the specified string to the file.

file = open("myfile.txt", "w")
file.write("Hello, File!")
file.close()
# No direct output, but content is written to myfile.txt
print("Content written to file.")

Content written to file.

#54. .read()
Reads the content of the file.

# Assuming "myfile.txt" contains "Hello, File!"
file = open("myfile.txt", "r")
content = file.read()
print(content)
file.close()

Hello, File!

#55. with
A context manager, often used with open() to automatically handle file closing.

with open("myfile.txt", "w") as f:
    f.write("This is safer!")
# The file is automatically closed here.
print("File written and closed safely.")

File written and closed safely.

---
#Python #Keywords #Advanced

#56. import
Used to import modules.

import math
print(math.sqrt(16))

4.0

#57. from ... import
Imports specific parts of a module.

from datetime import date
today = date.today()
print(today)

2023-10-27 
(Note: Output date will be the current date)

#58. in
Membership operator. Checks if a value is present in a sequence.

my_list = [1, 2, 3, 4, 5]
print(3 in my_list)
print(10 in my_list)

True
False

#59. del
Deletes an object (variable, list item, dictionary entry, etc.).

my_list = [10, 20, 30]
del my_list[1] # delete item at index 1
print(my_list)

[10, 30]

#60. pass
A null statement. It's used when a statement is required syntactically but you do not want any command or code to execute.

def my_empty_function():
    pass # To be implemented later

my_empty_function() # This does nothing and produces no error
print("Function executed without error.")

Function executed without error.

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By: @DataScience4 ✨