如何实现max_latitude函数计算观测对象的年度最大纬度

先修正原代码的一处错误 #

Obs类的__init__方法中，调用year_out_of_time时需使用实例方法的调用方式，原代码self.year = year_out_of_time(self)会报错，应改为：

self.year = self.year_out_of_time()

max_latitude函数实现方案 #

我们需要先按年份分组记录每个年份的最大纬度，再按照years函数返回的排序后年份列表提取对应最大值，保证输出的纵坐标与年份顺序完全匹配：

def max_latitude(observations):
    # 用字典存储每个年份的最大纬度，初始值设为极小值
    year_max_lat = {}
    for obs in observations:
        year = obs.year
        # 若年份未记录，或当前观测纬度更大，则更新该年份的最大纬度
        if year not in year_max_lat or obs.latitude > year_max_lat[year]:
            year_max_lat[year] = obs.latitude
    # 按照排序后的年份列表，提取对应的最大纬度值
    sorted_years = years(observations)
    return [year_max_lat[year] for year in sorted_years]

完整可运行代码片段 #

修正后的Obs类和完整函数实现：

import matplotlib.pyplot as plt  # 补充原代码缺失的plt导入

class Obs:
    def __init__(self, latitude, longitude, time, quantity):
        self.latitude = latitude
        self.longitude = longitude
        self.time = time
        self.quantity = quantity
        # 修正实例方法调用方式
        self.year = self.year_out_of_time()

    def year_out_of_time(self):
        date, time = self.time.split("T")
        year, month, day = date.split("-")
        return int(year)

def read_data(filename):
    observations = []
    try:
        with open(filename, "r") as f:
            next(f)  # 跳过首行表头
            for line in f:
                if line.endswith("Artportalen\n"):
                    latitude, longitude, time, quantity, Artportalen = line.split(",")
                else:
                    latitude, longitude, time, quantity = line.split(",")
                latitude = float(latitude)
                longitude = float(longitude)
                quantity = int(quantity.strip())
                time = time.strip("Z")
                observations.append(Obs(latitude, longitude, time, quantity))
    except Exception as e:
        print("Error:", e)
    return observations

def years(observations):
    out = []
    for obs in observations:
        if obs.year not in out:
            out.append(obs.year)
    return sorted(out)

def max_latitude(observations):
    year_max_lat = {}
    for obs in observations:
        year = obs.year
        if year not in year_max_lat or obs.latitude > year_max_lat[year]:
            year_max_lat[year] = obs.latitude
    sorted_years = years(observations)
    return [year_max_lat[year] for year in sorted_years]

def plot_data(observations):
    xpoints = years(observations)
    ypoints = max_latitude(observations)
    plt.title("年度最大纬度")
    plt.xlabel("年份")
    plt.ylabel("最大纬度")
    plt.scatter(xpoints, ypoints)
    plt.show()

说明 #

• 字典year_max_lat用于高效记录各年份的最大纬度，仅需遍历一次观测数据即可完成统计，时间复杂度为O(n)
• 最后通过排序后的年份列表生成结果，确保与years函数返回的X轴年份顺序完全对应
• 补充了原代码缺失的matplotlib.pyplot导入，并适配了中文图表标题

内容的提问来源于stack exchange，提问作者pythonhelpneeded