Writing Functions

def function_name(parameters):

Define a customizable function in Python.

Input:

parameters: any data type

These parameters are variables that act as placeholders for the values you pass to the function. A function can take a single parameter or a comma-separated list of parameters. Including parameters is optional; a function may operate without any.

Returns:

The result of the function. If there is no return statement, the function returns None by default.

Return Type:

The type of the returned object depends on the value provided by the return expression. If no return statement is used, the return type is NoneType.

The diagram below provides an example of how a function is composed. For additional helpful visual guides, please visit the Diagrams site.

(Source)

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def is_dog(species):
    """
    Sees if the species is a dog.
    ---
    Input:
        species: a string
    ---
    Output:
        a boolean
    """
    if species == 'dog':
        return True
    return False

is_dog('dog')

True

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def categorize_animal(index):
    """
    Categorizes the animal based on its species, weight, and age.
    ---
    Input:
        index: a string containing the ID of the animal
    ---
    Output:
        a string describing the animal
    """
    pets_idx = pets.set_index('ID')
    species = pets_idx.loc[index].get('Species')
    weight = pets_idx.loc[index].get('Weight')
    age = pets_idx.loc[index].get('Age')
    
    # Initialize descriptors
    life_stage = ''
    weight_status = ''
    
    # Define thresholds for dogs
    if species == 'dog':
        if age < 2:
            life_stage = 'Puppy'
        elif age < 7:
            life_stage = 'Adult'
        else:
            life_stage = 'Senior'
        
        if weight < 20:
            weight_status = 'Underweight'
        elif weight <= 60:
            weight_status = 'Normal'
        else:
            weight_status = 'Overweight'
    
    # Define thresholds for cats
    elif species == 'cat':
        if age < 2:
            life_stage = 'Kitten'
        elif age < 10:
            life_stage = 'Adult'
        else:
            life_stage = 'Senior'
        
        if weight < 2:
            weight_status = 'Underweight'
        elif weight <= 10:
            weight_status = 'Normal'
        else:
            weight_status = 'Overweight'
    
    # Define thresholds for hamsters
    elif species == 'hamster':
        if age < 0.5:
            life_stage = 'Young'
        elif age < 2:
            life_stage = 'Adult'
        else:
            life_stage = 'Senior'
        
        if weight < 0.2:
            weight_status = 'Underweight'
        elif weight <= 0.5:
            weight_status = 'Normal'
        else:
            weight_status = 'Overweight'
    
    # Return a combined description as a single string
    return f"{life_stage} {weight_status}"

categorize_animal(pets.get('ID').iloc[0])

'Adult Normal'

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