Python中合并多个字典并按年份汇总Total值的方法

首先要指出你给出的州字典写法存在问题：Python 字典不允许重复键，像 Indiana = {Year:2018, Total:102, Year:2017, Total:84....} 这种写法会直接覆盖重复的键，最终每个州的字典只会保留最后一组 Year 和 Total，完全不符合数据存储需求。

先把数据改成合理结构，再实现按年份汇总的功能，下面分两种常见的合理结构给出实现代码：

情况1：每个州的字典以年份为键，Total为值 #

示例数据：

Indiana = {2018: 102, 2017: 84}
Alabama = {2018: 115, 2017: 116}
Colorado = {2018: 71, 2017: 76}

汇总代码：

# 把所有州的字典存入一个列表
state_data = [Indiana, Alabama, Colorado]
continentals = {}

for state in state_data:
    for year, total in state.items():
        if year in continentals:
            continentals[year] += total
        else:
            continentals[year] = total

# 若需要转换成「Year/Total 成对」的结构（注意：Python 字典不支持重复键，因此用列表嵌套字典）
continentals_list = [{"Year": year, "Total": total} for year, total in continentals.items()]
print(continentals_list)

情况2：每个州的数据是包含年份和Total的字典列表 #

示例数据：

Indiana = [{"Year": 2018, "Total": 102}, {"Year": 2017, "Total": 84}]
Alabama = [{"Year": 2018, "Total": 115}, {"Year": 2017, "Total": 116}]
Colorado = [{"Year": 2018, "Total": 71}, {"Year": 2017, "Total": 76}]

汇总代码：

state_data = [Indiana, Alabama, Colorado]
continentals = {}

for state in state_data:
    for entry in state:
        year = entry["Year"]
        total = entry["Total"]
        if year in continentals:
            continentals[year] += total
        else:
            continentals[year] = total

# 转换成列表嵌套字典的结构
continentals_list = [{"Year": year, "Total": total} for year, total in continentals.items()]
print(continentals_list)

重要说明 #

你想要的 Continentals = {Year:2018, Total:xxx, Year:2017, Total:xxx} 结构在 Python 里无法实现，因为字典的键必须唯一，重复的 Year 和 Total 键会被直接覆盖。因此最终只能用「年份为键、汇总Total为值」的字典，或者列表嵌套字典的形式来存储每一年的汇总数据。

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