如何用Python更新已有JSON文件？含特定字段修改场景

现有代码与数据结构 #

读取JSON文件的代码 #

f = open("data.json", "r")
data = np.array(json.loads(f.read()))

数据结构示例 #

[
    {
        "symbol" : "NZDCHF",
        "timeframe" : [
            {"tf":"H4","x1":0,"y1":0,"x2":0,"y2":0},
            {"tf":"H1","x1":0,"y1":0,"x2":0,"y2":0},
            {"tf":"M30","x1":0,"y1":0,"x2":0,"y2":0},
            {"tf":"M15","x1":0,"y1":0,"x2":0,"y2":0},
            {"tf":"M5","x1":0,"y1":0,"x2":0,"y2":0}
        ]  
    },
    {
        "symbol" : "AUDCHF",
        "timeframe" : [
            {"tf":"H4","x1":0,"y1":0,"x2":0,"y2":0},
            {"tf":"H1","x1":0,"y1":0,"x2":0,"y2":0},
            {"tf":"M30","x1":0,"y1":0,"x2":0,"y2":0},
            {"tf":"M15","x1":0,"y1":0,"x2":0,"y2":0},
            {"tf":"M5","x1":0,"y1":0,"x2":0,"y2":0}
        ]  
    }
]

查找指定内容的代码 #

selected = np.array([el for el in data if el["symbol"] == 'AUDCHF'])
rect = selected[0]['timeframe'][4]

字段更新与写回步骤 #

1. 更新指定字段值 #

rect是对原data中字典的直接引用，修改它的键值对会同步更新原数据：

# 替换为你需要的目标数值
rect['x1'] = 100
rect['y1'] = 200
rect['x2'] = 300
rect['y2'] = 400

2. 处理数据格式（解决numpy序列化问题） #

JSON无法直接序列化numpy数组，需要先转换为普通Python列表：

data_list = data.tolist()

3. 写入更新后的JSON文件 #

用with语句自动管理文件开闭，indent=4让输出的JSON格式化，可读性更强：

import json

with open("data.json", "w") as f:
    json.dump(data_list, f, indent=4)

优化建议 #

没必要将JSON读取结果转为numpy数组，直接用Python列表即可简化操作：

import json

# 优化读取逻辑
with open("data.json", "r") as f:
    data = json.load(f)

# 优化查找逻辑
selected = [el for el in data if el["symbol"] == 'AUDCHF'][0]
rect = selected['timeframe'][4]

# 更新字段
rect['x1'] = 100
rect['y1'] = 200
rect['x2'] = 300
rect['y2'] = 400

# 直接写入文件
with open("data.json", "w") as f:
    json.dump(data, f, indent=4)

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