Python Type Conversion

Practical Applications

CSV Data Processing

import csv

def process_csv_data(filename):
    """
    Read a CSV file and convert data to appropriate types.
    """
    data = []
    
    with open(filename, 'r', newline='') as file:
        reader = csv.DictReader(file)
        
        for row in reader:
            # Convert string values to appropriate types
            processed_row = {}
            
            for key, value in row.items():
                # Skip empty values
                if value == '':
                    processed_row[key] = None
                    continue
                
                # Try to convert to appropriate type
                try:
                    # Try integer conversion first
                    processed_row[key] = int(value)
                except ValueError:
                    try:
                        # Try float conversion
                        processed_row[key] = float(value)
                    except ValueError:
                        # Handle boolean values
                        if value.lower() in ('true', 'yes', 'y'):
                            processed_row[key] = True
                        elif value.lower() in ('false', 'no', 'n'):
                            processed_row[key] = False
                        else:
                            # Keep as string if no conversion works
                            processed_row[key] = value
            
            data.append(processed_row)
    
    return data

# Example of how this would be used (uncomment to test with a real CSV file)
# csv_data = process_csv_data('data.csv')
# for row in csv_data:
#     print(row)

Temperature Converter

def temperature_converter():
    """
    Simple temperature converter between Celsius and Fahrenheit.
    """
    print("Temperature Converter")
    print("=====================")
    
    while True:
        temp_str = input("Enter temperature (e.g., '32F', '0C'): ")
        
        if not temp_str:
            break
        
        try:
            # Extract the numerical value and unit
            if temp_str[-1].upper() in ('C', 'F'):
                value = float(temp_str[:-1])
                unit = temp_str[-1].upper()
            else:
                # Assume Celsius if no unit is provided
                value = float(temp_str)
                unit = 'C'
            
            # Convert between units
            if unit == 'C':
                fahrenheit = (value * 9/5) + 32
                print(f"{value}°C = {fahrenheit:.1f}°F")
            else:
                celsius = (value - 32) * 5/9
                print(f"{value}°F = {celsius:.1f}°C")
        
        except ValueError:
            print("Invalid temperature format. Please use formats like '32F' or '0C'.")
        
        print()  # Empty line for readability
    
    print("Goodbye!")

# Uncomment to run the temperature converter
# temperature_converter()

Custom Type Conversion for Objects

class Point:
    """A 2D point class with x and y coordinates."""
    
    def __init__(self, x, y):
        self.x = x
        self.y = y
    
    def __str__(self):
        return f"Point({self.x}, {self.y})"
    
    def __repr__(self):
        return f"Point({self.x}, {self.y})"
    
    # Convert Point to tuple
    def to_tuple(self):
        return (self.x, self.y)
    
    # Convert Point to dict
    def to_dict(self):
        return {"x": self.x, "y": self.y}
    
    # Static method to create Point from tuple
    @staticmethod
    def from_tuple(t):
        return Point(t[0], t[1])
    
    # Static method to create Point from dict
    @staticmethod
    def from_dict(d):
        return Point(d["x"], d["y"])
    
    # Static method to create Point from string
    @staticmethod
    def from_string(s):
        # Expected format: "Point(x, y)" or "(x, y)"
        s = s.strip()
        if s.startswith("Point("):
            s = s[6:-1]  # Remove "Point(" and ")"
        elif s.startswith("(") and s.endswith(")"):
            s = s[1:-1]  # Remove "(" and ")"
        
        # Split by comma and convert to floats
        parts = s.split(",")
        if len(parts) != 2:
            raise ValueError("String must contain exactly two values")
        
        try:
            x = float(parts[0].strip())
            y = float(parts[1].strip())
            return Point(x, y)
        except ValueError:
            raise ValueError("Could not convert string coordinates to float")

# Examples
p1 = Point(3, 4)
print(p1)  # Point(3, 4)

# Convert to other types
tuple_version = p1.to_tuple()
print(tuple_version)  # (3, 4)

dict_version = p1.to_dict()
print(dict_version)  # {'x': 3, 'y': 4}

# Convert from other types back to Point
p2 = Point.from_tuple((5, 6))
print(p2)  # Point(5, 6)

p3 = Point.from_dict({"x": 7, "y": 8})
print(p3)  # Point(7, 8)

p4 = Point.from_string("Point(9, 10)")
print(p4)  # Point(9.0, 10.0)

p5 = Point.from_string("(11, 12)")
print(p5)  # Point(11.0, 12.0)