Data Type Conversion in Python

Data type conversion in Python allows you to transform one data type into another. Python provides built-in functions to perform these conversions, which return new objects representing the converted values.

Common Type Conversion Functions

Converting to Numeric Types

String to Integer

Convert string numbers to integers using int() ?

# String to integer conversion
number_str = "42"
number_int = int(number_str)
print(f"String: {number_str}, Type: {type(number_str)}")
print(f"Integer: {number_int}, Type: {type(number_int)}")

# With different bases
binary_str = "1010"
decimal_from_binary = int(binary_str, 2)
print(f"Binary '1010' to decimal: {decimal_from_binary}")

String: 42, Type: <class 'str'>
Integer: 42, Type: <class 'int'>
Binary '1010' to decimal: 10

String to Float

Convert strings to floating-point numbers ?

# String to float conversion
price_str = "19.99"
price_float = float(price_str)
print(f"String: {price_str}, Type: {type(price_str)}")
print(f"Float: {price_float}, Type: {type(price_float)}")

# Scientific notation
scientific = "1.5e3"
result = float(scientific)
print(f"Scientific notation: {scientific} = {result}")

String: 19.99, Type: <class 'str'>
Float: 19.99, Type: <class 'float'>
Scientific notation: 1.5e3 = 1500.0

Converting to String Type

Use str() to convert any object to its string representation ?

# Various types to string
number = 42
pi = 3.14159
is_active = True
data = [1, 2, 3]

print(f"Integer to string: {str(number)}")
print(f"Float to string: {str(pi)}")
print(f"Boolean to string: {str(is_active)}")
print(f"List to string: {str(data)}")

Integer to string: 42
Float to string: 3.14159
Boolean to string: True
List to string: [1, 2, 3]

Converting Between Collection Types

Convert between lists, tuples, and sets ?

# Original list
numbers = [1, 2, 3, 2, 4]

# Convert to different types
numbers_tuple = tuple(numbers)
numbers_set = set(numbers)  # Removes duplicates
numbers_back_to_list = list(numbers_set)

print(f"Original list: {numbers}")
print(f"To tuple: {numbers_tuple}")
print(f"To set: {numbers_set}")
print(f"Back to list: {numbers_back_to_list}")

Original list: [1, 2, 3, 2, 4]
To tuple: (1, 2, 3, 2, 4)
To set: {1, 2, 3, 4}
Back to list: [1, 2, 3, 4]

Character and ASCII Conversions

Convert between characters and their ASCII values ?

# Character to ASCII and back
char = 'A'
ascii_value = ord(char)
back_to_char = chr(ascii_value)

print(f"Character: {char}")
print(f"ASCII value: {ascii_value}")
print(f"Back to character: {back_to_char}")

# Convert number to hex and octal
number = 255
hex_value = hex(number)
oct_value = oct(number)

print(f"Number: {number}")
print(f"Hexadecimal: {hex_value}")
print(f"Octal: {oct_value}")

Character: A
ASCII value: 65
Back to character: A
Number: 255
Hexadecimal: 0xff
Octal: 0o377

Boolean Conversion

Python follows specific rules for boolean conversion ?

# Different values to boolean
values = [0, 1, "", "hello", [], [1, 2], None]

for value in values:
    boolean_result = bool(value)
    print(f"{repr(value):10} ? {boolean_result}")

0          ? False
1          ? True
''         ? False
'hello'    ? True
[]         ? False
[1, 2]     ? True
None       ? False

Handling Conversion Errors

Some conversions may fail and raise exceptions ?

# Safe conversion with error handling
def safe_int_convert(value):
    try:
        return int(value)
    except ValueError:
        return f"Cannot convert '{value}' to integer"

test_values = ["42", "3.14", "hello", ""]
for value in test_values:
    result = safe_int_convert(value)
    print(f"Converting '{value}': {result}")

Converting '42': 42
Converting '3.14': Cannot convert '3.14' to integer
Converting 'hello': Cannot convert 'hello' to integer
Converting '': Cannot convert '' to integer

Conclusion

Python's built-in type conversion functions make it easy to transform data between different types. Always handle potential conversion errors when working with user input or uncertain data sources.