如何用Python编辑复杂JSON数据并计算营养成分值

需求说明 #

我生成了一个包含units数组的JSON对象，数组内对象数量不固定。其中units第一个对象的键和值已分别存储在first_keys = []和first_values = []中。需要实现：

• 计算第2个及以后对象的营养值（如carb、protein等），公式为：当前对象amount × 第一个对象对应营养值 ÷ 第一个对象amount
• 保留原有的单位格式（比如"g"、"kcal"）

示例JSON结构 #

{
    "food_id": 0,
    "food_name": "NAME",
    "food_image": "IMAGE",
    "food_kcal": "KCAL",
    "food_url": "FOOD_URL",
    "food_description": "DESC",
    "meal_time": "null",
    "food_category": "",
    "food_first_unit": "Yemek Kaşığı",
    "carb_percent": "72",
    "protein_percent": "23",
    "fat_percent": "4",
    "units": [
        {
            "unit": "100 Gram",
            "amount": "100",
            "kcal": "505 kcal",
            "carb": "65 g",
            "fiber": "3 g",
            "protein": "5 g",
            "fat": "24 g",
            "saturated_fat": "10 g",
            "salt": "0.7 g",
            "sugar": "34 g"
        },
        {
            "unit": "1 Adet",
            "amount": "5",
            "kcal": "",
            "carb": "",
            "fiber": "",
            "protein": "",
            "fat": "",
            "saturated_fat": "",
            "salt": "",
            "sugar": ""
        },
        {
            "unit": "1 Porsiyon",
            "amount": "30",
            "kcal": "",
            "carb": "",
            "fiber": "",
            "protein": "",
            "fat": "",
            "saturated_fat": "",
            "salt": "",
            "sugar": ""
        },
        {
            "unit": "1 Paket",
            "amount": "90",
            "kcal": "",
            "carb": "",
            "fiber": "",
            "protein": "",
            "fat": "",
            "saturated_fat": "",
            "salt": "",
            "sugar": ""
        }
    ]
}

现有代码 #

import requests
from bs4 import BeautifulSoup
import json

url = 'www.example.com'
response = requests.get(url)
response.encoding = 'utf-8'
html = response.text

soup = BeautifulSoup(html, 'html.parser')
items = soup.find_all('li')

units = []
first_key = []
first_values = []
names = []
grams = []

for item in items:
    name = item.get('data-ntr-srvname-param')
    if(str(name) not in "None"):
        names.append(str(name).replace("Gramda", "Gram"))


items = soup.find_all("li", {"data-ntr-gram-param": True})
for item in items:
    grams.append(float(item["data-ntr-gram-param"]))


for row in soup.select('table[data-ntr-target="facts"] tr'):
    name = row.select_one('td:nth-of-type(1)')
    value = row.select_one('td:nth-of-type(2)')

    if name is not None and value is not None:
        first_key.append(name.text.strip())
        first_values.append(value.text.strip())


for index, gram in enumerate(grams):
    replacedGram=str(gram).replace(".0", "")
    units.append({
        "unit": f"{names[index]}",
        "amount": f"{replacedGram}"
    })


data_dict = dict(zip(first_key, first_values))
for index, gram in enumerate(grams):
    units[index].update(data_dict)

json_obj = {
    "food_id": 0,
    "food_name": "NAME",
    "food_image": "IMAGE",
    "food_kcal": "KCAL",
    "food_url": "FOOD_URL",
    "food_description": "DESC",
    "meal_time": "null",
    "food_category":"",
    "food_first_unit": "FIRST",
    "carb_percent": "72",
    "protein_percent": "23",
    "fat_percent": "4",
    "units": units
}

print("***************")

print(json.dumps(json_obj, indent=4, ensure_ascii=False))

print("***************")

修改后的实现代码 #

要完成营养值计算，需先解析第一个单位的数值与单位，再遍历后续单位批量计算：

import requests
from bs4 import BeautifulSoup
import json

url = 'www.example.com'
response = requests.get(url)
response.encoding = 'utf-8'
html = response.text

soup = BeautifulSoup(html, 'html.parser')
items = soup.find_all('li')

units = []
first_keys = []
first_values = []
names = []
grams = []

# 提取单位名称
for item in items:
    name = item.get('data-ntr-srvname-param')
    if name is not None:
        names.append(str(name).replace("Gramda", "Gram"))

# 提取每个单位的amount值
items = soup.find_all("li", {"data-ntr-gram-param": True})
for item in items:
    grams.append(float(item["data-ntr-gram-param"]))

# 提取第一个单位的营养键值对
for row in soup.select('table[data-ntr-target="facts"] tr'):
    name = row.select_one('td:nth-of-type(1)')
    value = row.select_one('td:nth-of-type(2)')
    if name is not None and value is not None:
        first_keys.append(name.text.strip())
        first_values.append(value.text.strip())

# 构建基础units数组
for index, gram in enumerate(grams):
    replaced_gram = str(gram).replace(".0", "")
    units.append({
        "unit": names[index],
        "amount": replaced_gram
    })

# 解析第一个单位的数值和单位，生成计算模板
first_amount = float(units[0]["amount"])
nutrient_template = {}
for key, value in zip(first_keys, first_values):
    # 拆分数值和单位（兼容"505 kcal"、"65 g"、"0.7 g"等格式）
    parts = value.split()
    if len(parts) == 2:
        num, unit = parts
        nutrient_template[key] = (float(num), unit)
    elif len(parts) == 1:
        # 处理无单位的特殊情况（可根据实际需求调整）
        nutrient_template[key] = (float(parts[0]), "")

# 给第一个单位填充完整营养值
for key, (num, unit) in nutrient_template.items():
    units[0][key] = f"{num} {unit}" if unit else str(num)

# 计算后续单位的营养值
for unit in units[1:]:
    current_amount = float(unit["amount"])
    ratio = current_amount / first_amount
    for key, (base_num, unit_str) in nutrient_template.items():
        calculated_num = base_num * ratio
        # 优化数值显示格式：整数显示为整数，小数保留1位
        if calculated_num.is_integer():
            calculated_num = int(calculated_num)
        else:
            calculated_num = round(calculated_num, 1)
        unit[key] = f"{calculated_num} {unit_str}" if unit_str else str(calculated_num)

# 构建最终JSON对象
json_obj = {
    "food_id": 0,
    "food_name": "NAME",
    "food_image": "IMAGE",
    "food_kcal": "KCAL",
    "food_url": "FOOD_URL",
    "food_description": "DESC",
    "meal_time": "null",
    "food_category": "",
    "food_first_unit": "FIRST",
    "carb_percent": "72",
    "protein_percent": "23",
    "fat_percent": "4",
    "units": units
}

print("***************")
print(json.dumps(json_obj, indent=4, ensure_ascii=False))
print("***************")

关键实现说明 #

1. 营养模板解析：将第一个单位的营养值拆分为数值和单位，确保计算后保留原格式
2. 比例计算：通过当前单位amount与第一个单位amount的比值，批量计算所有营养项
3. 数值格式优化：自动判断整数/小数，提升输出可读性
4. 批量填充：遍历后续单位，一次性完成所有营养字段的计算与填充

内容的提问来源于stack exchange，提问作者Deniz