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python - Python，避免丑陋的嵌套 for 循环

问题描述

我是 python 编程的新手。我已经尝试了很多来避免这些嵌套的 for 循环，但没有成功。

我的数据输入如下：

[
  {
    "province_id": "1",
    "name": "HCM",
    "districts": [
      {
        "district_id": "1",
        "name": "Thu Duc",
        "wards": [
          {
            "ward_id": "1",
            "name": "Linh Trung"
          },
          {
            "ward_id": "2",
            "name": "Linh Chieu"
          }
        ]
      },
      {
        "district_id": "2",
        "name": "Quan 9",
        "wards": [
          {
            "ward_id": "3",
            "name": "Hiep Phu"
          },
          {
            "ward_id": "4",
            "name": "Long Binh"
          }
        ]
      }
    ]
  },
  {
    "province_id": "2",
    "name": "Binh Duong",
    "districts": [
      {
        "district_id": "3",
        "name": "Di An",
        "wards": [
          {
            "ward_id": "5",
            "name": "Dong Hoa"
          },
          {
            "ward_id": "6",
            "name": "Di An"
          }
        ]
      },
      {
        "district_id": "4",
        "name": "Thu Dau Mot",
        "wards": [
          {
            "ward_id": "7",
            "name": "Hiep Thanh"
          },
          {
            "ward_id": "8",
            "name": "Hiep An"
          }
        ]
      }
    ]
  }
]

我的代码是：

for province in data:
    for district in province['districts']:
        for ward in district['wards']:
            # Excute my function
            print('{}, {}, {}'.format(ward['name'], district['name'], province['name']))

输出

Linh Trung, Thu Duc, HCM
Linh Chieu, Thu Duc, HCM
Hiep Phu, Quan 9, HCM
...

即使我的代码正在运行，它看起来也很丑陋。
如何避免这些嵌套的 for 循环？

标签： pythonnested-loops

解决方案

您的数据结构自然是嵌套的，但是您可以选择一种用于整理代码的方法是编写一个生成器函数来对其进行迭代：

def all_wards(data):
    for province in data:
        for district in province['districts']:
            for ward in district['wards']:
                yield province, district, ward

这个函数和你现在有相同的三重嵌套循环，但是在你的代码中的其他地方，你现在可以用一个非嵌套循环遍历数据结构：

for province, district, ward in all_wards(data):
    print('{}, {}, {}'.format(ward['name'], district['name'], province['name']))

如果您希望避免缩进过多，这是编写函数的等效方法，类似于@adarian 的答案，但不创建临时列表：

def all_wards(data):
    return (
        province, district, ward
        for province in data
        for district in province['districts']
        for ward in district['wards']
    )

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