Iterating Over Data Structures in Python

Iterating Over Data Structures

• Lists: Iterate over elements using for loop
  • for element in list:
  • for index, element in enumerate(list): (access both index and element)
• Tuples: Iterate over elements using for loop
  • for element in tuple:
• Dictionaries: Iterate over key-value pairs using for loop
  • for key, value in dictionary.items():
  • for key in dictionary.keys(): (iterate over keys only)
  • for value in dictionary.values(): (iterate over values only)

Loop Control Statements

• Break: Exit the loop prematurely
  • break statement
• Continue: Skip to the next iteration
  • continue statement
• Pass: Do nothing (used as a placeholder)
  • pass statement

Nested Loops

• Nested For Loops: Iterate over multiple data structures
  • for element1 in list1:
  • for element2 in list2:
• Nested While Loops: Iterate over multiple conditions
  • while condition1:
  • while condition2:

While Loops

• Basic Syntax: while condition do something
  • while condition:
  • statement
• Infinite Loop: Use while True to create an infinite loop
  • while True:
  • statement

For Loops

• Basic Syntax: for variable in iterable do something
  • for variable in iterable:
  • statement
• Range Function: Iterate over a range of numbers
  • for variable in range(start, stop, step):
• Enumerate Function: Iterate over both index and value
  • for index, value in enumerate(iterable):

Iterating Over Data Structures

• Lists can be iterated over using a for loop with the syntax for element in list:
• Lists can also be iterated over with both index and element using for index, element in enumerate(list):
• Tuples can be iterated over using a for loop with the syntax for element in tuple:
• Dictionaries can be iterated over using a for loop with the syntax for key, value in dictionary.items(): to access both key and value
• Dictionaries can be iterated over using a for loop with the syntax for key in dictionary.keys(): to access only the keys
• Dictionaries can be iterated over using a for loop with the syntax for value in dictionary.values(): to access only the values

Loop Control Statements

• The break statement is used to exit a loop prematurely
• The continue statement is used to skip to the next iteration
• The pass statement is used as a placeholder and does nothing

Nested Loops

• Nested for loops can be used to iterate over multiple data structures
• Nested while loops can be used to iterate over multiple conditions

While Loops

• The basic syntax for a while loop is while condition: statement
• The while True statement can be used to create an infinite loop

For Loops

• The basic syntax for a for loop is for variable in iterable: statement
• The range function can be used to iterate over a range of numbers with the syntax for variable in range(start, stop, step):
• The enumerate function can be used to iterate over both index and value with the syntax for index, value in enumerate(iterable):