Week-3-2

Python Lists

• Length of a List: To find the length of a list, use the LEN function.

  • Example: LEN([1, 2, 3, 4, 5]) returns 5.

• Concatenation of Lists: Use the + sign to concatenate two lists.

  • Results in a larger combined list.

• Minimum and Maximum Values:

  • Use the min() function to find the smallest element in a list. All elements must be of the same type for this function to work.

  • Use the max() function to find the largest element.

• Homogeneous Lists: Python lists can contain different data types (e.g., integers, strings), but min() and max() require homogeneous elements.

• Sum of List Items: sum(list) returns the sum of numeric items in the list.

• Index Method: list.index(value) returns the index of the first occurrence of value in the list.

• Count Method: list.count(value) gives the number of times value appears in the list.

Example Program: House Prices

• Initial List of House Prices: Start with a list of house prices.

• Appending New Prices: Use list concatenation to add new prices.

• Print Number of Prices: Use LEN function to display how many prices are in the list.

  • Example Output: "There are 4 prices in the list."

• Finding the Lowest Price: Use min() to find the lowest price, e.g., min(house_prices) returns the lowest price.

  • Example Output: "The most affordable house is for sale at $225,000."

• Closing Costs: Define additional costs in a list and calculate total costs by summing house price and closing costs.

  • Example: total_cost = lowest_cost + sum(closing_costs).

• Print Total Cost: Ensure to convert final result to an integer for clarity.

Example Program: Student Grades

• Lists of Scores: Contains midterm and final exam scores.

• Concatenation: Combine midterm and final scores into a single list.

• Counting Scores with LEN: Use LEN to count and print the number of scores for both midterm and final exams.

• Calculation of Dropped Students: Subtract the number of final exam scores from midterm scores to find the number of students who dropped.

  • Example output: "Number of students who dropped: X."

• Finding Minimum and Maximum Final Scores:

  • Use min(final_scores) to find the lowest score.

  • Use max(final_scores) to find the highest score.

• Range Printing: Use formatted strings to print the range of final scores.

Python Tuples

• Definition: A tuple is a sequence type resembling a list, but defined with parentheses.

• Immutability: Once a tuple is defined, it cannot be modified (immutable).

• Accessing Elements: Use indexing, e.g., tuple[index].

• Examples: Define a tuple for coordinates, e.g., coordinates = (lat, long).

Named Tuples

• Definition: A named tuple is a subclass of tuples with named fields.

• Creation: Import from collections, define with attributes (e.g., Car: make, model, price).

• Accessing Fields: Access attributes by specifying the tuple name followed by the attribute name.

Python Sets

• Definition: An unordered collection of unique elements.

• Creation: Sets can be created using curly braces or the set() function.

• Adding Elements: Use the add() method, which ignores duplicates.

• Removing Elements: The remove() method deletes specified elements, raising an error if not found.

• Empty Set: Could only be created using set().

Set Operations

• Union: Combines sets, eliminating duplicates.

  • Example: set1.union(set2).

• Intersection: Finds common elements between sets.

  • Example: set1.intersection(set3).

• Difference: Removes elements from one set that exist in another.

  • Example: set1.difference(set4).

Python Dictionaries

• Definition: A collection of key-value pairs defined within curly braces.

• Accessing Values: Use dict[key] to access the value associated with a key.

• Modifying Values: Update values by reassigning using dict[key] = new_value.

• Deleting Items: Use del dict[key] to remove a key-value pair from the dictionary.

Summary of Python Types

• Numeric Types: Include integers and floats (floating-point numbers).

• Sequence Types: Include strings, lists, tuples (ordered collections).

• Mapping Type: Represented by dictionaries which associate keys with values.

• Set Types: Include unordered and unique elements (sets).

Binary Numbers

• Definition: Binary uses two digits (0 and 1) for representation.

• Decimal to Binary Interpretation: Understand positional weight in binary, converting between the two numerical systems.

  • Example: A binary number has a weight based on its position, similar to decimal.

• Example of Conversion: Convert 1101 binary to decimal by evaluating positional weights.