Python类中为运动强度赋值并计算卡路里的问题求助

Hey there! Let's work through your problem together. You've got two key issues here: your setter methods aren't updating the instance properties correctly, and you need a clean way to map intensity levels to their calorie multiplier values. Let's tackle them one by one.

First: Fix the Setter Methods #

Looking at your set_exercise, set_intensity, and set_duration methods, you're making a common mistake—you're assigning the new value to self.set_exercise (the method itself) instead of self.exercise (the instance property). That's why your updates aren't sticking! Here's how to fix each setter:

def set_exercise(self, exercise):
    self.exercise = exercise  # Assign to the instance property, not the method

def set_intensity(self, intensity):
    self.intensity = intensity

def set_duration(self, duration):
    self.duration = duration

Also, your get_duration method has a small issue: it's trying to concatenate an integer (self.duration) with a string, which will throw an error. You need to convert the duration to a string first:

def get_duration(self):
    return f"{self.duration} minutes"  # F-strings make this clean and readable

Second: Map Intensity to Calorie Values #

For the intensity-to-number mapping, using a class-level dictionary is the perfect approach—it's clean, reusable, and easy to update. You can define this dictionary inside the ExerciseSession class (outside any methods) so all instances can access it. Then, add a method to calculate calories based on duration and intensity.

Here's the updated class with this logic:

class ExerciseSession:
    # Class-level dictionary to map intensity to calorie multipliers
    INTENSITY_MULTIPLIERS = {
        "Low": 3,
        "Medium": 6,
        "High": 12
    }

    def __init__(self, exercise, intensity, duration):
        self.exercise = exercise
        self.intensity = intensity
        self.duration = duration

    def get_exercise(self):
        return self.exercise

    def get_intensity(self):
        return self.intensity

    def get_duration(self):
        return f"{self.duration} minutes"

    def set_exercise(self, exercise):
        self.exercise = exercise

    def set_intensity(self, intensity):
        # Optional: Add a check to ensure intensity is valid
        if intensity in self.INTENSITY_MULTIPLIERS:
            self.intensity = intensity
        else:
            raise ValueError(f"Invalid intensity. Choose from {list(self.INTENSITY_MULTIPLIERS.keys())}")

    def set_duration(self, duration):
        self.duration = duration

    def calculate_calories(self):
        # Get the multiplier, default to 0 if intensity is invalid (avoids crashes)
        multiplier = self.INTENSITY_MULTIPLIERS.get(self.intensity, 0)
        return self.duration * multiplier

How This Works: #

• INTENSITY_MULTIPLIERS is a class variable, so every ExerciseSession instance uses the same mapping—no need to redefine it for each object.
• The calculate_calories method uses dict.get() to safely retrieve the multiplier (returns 0 if the intensity isn't in the dictionary, which prevents unexpected errors).
• The updated set_intensity includes a validation check to make sure only valid intensity values are set—this is optional but helps catch mistakes early.

Testing the Updated Code #

If you run your test code now, plus call the new calculate_calories method, it should work as expected:

new_exercise = ExerciseSession("Running", "Low", 60)
print(new_exercise.get_exercise())  # Output: Running
print(new_exercise.get_intensity())  # Output: Low
print(new_exercise.get_duration())  # Output: 60 minutes
print(new_exercise.calculate_calories())  # Output: 180 (60 * 3)

new_exercise.set_exercise("Swimming")
new_exercise.set_intensity("High")
new_exercise.set_duration(30)
print(new_exercise.get_exercise())  # Output: Swimming
print(new_exercise.get_intensity())  # Output: High
print(new_exercise.get_duration())  # Output: 30 minutes
print(new_exercise.calculate_calories())  # Output: 360 (30 * 12)

Key Takeaways #

• Setter methods should update the instance's properties (like self.exercise), not the method itself.
• Class-level dictionaries are ideal for storing fixed mappings (like intensity to values) that all instances need access to—they're more maintainable than a bunch of if/elif statements.
• Always validate inputs (like intensity) if you can—it prevents unexpected errors down the line.

内容的提问来源于stack exchange，提问作者TommyD543