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我正在尝试使用 Google Refine 从数据科学工具包坐标 2 政治 API 的结果中提取特定元素。

这是示例单元#1：

[{"politics":[
 {"type":"admin2","friendly_type":"country","code":"usa","name":"United States"},
 {"type":"admin6","friendly_type":"county","code":"55_025","name":"Dane"},
 {"type":"constituency","friendly_type":"constituency","code":"55_02","name":"Second district, WI"},
 {"type":"admin5","friendly_type":"city","code":"55_48000","name":"Madison"},
 {"type":"admin5","friendly_type":"city","code":"55_53675","name":"Monona"},
 {"type":"admin4","friendly_type":"state","code":"us55","name":"Wisconsin"},
 {"type":"neighborhood","friendly_type":"neighborhood","code":"Eastmorland|Madison|WI","name":"Eastmorland"}
 ],"location":{"longitude":"-89.3259404","latitude":"43.0859191"}}]

我使用此 GREL 语法在此列的基础上添加了一个列，以提取 Dane 县：

value.parseJson()[0]["politics"][1]["name"]

但是当我到达 Sample Cell #2 时，语法不再有效，因为 JSON 结果有点不同：

[{"politics":[
 {"type":"admin2","friendly_type":"country","code":"usa","name":"United States"},
 {"type":"constituency","friendly_type":"constituency","code":"55_05","name":"Fifth district, WI"},
 {"type":"admin4","friendly_type":"state","code":"us55","name":"Wisconsin"},
 {"type":"admin6","friendly_type":"county","code":"55_079","name":"Milwaukee"},
 {"type":"admin5","friendly_type":"city","code":"55_84675","name":"Wauwatosa"},
 {"type":"constituency","friendly_type":"constituency","code":"55_04","name":"Fourth district, WI"}
 ],"location":{"longitude":"-88.0075875","latitude":"43.0494572"}}]

是否有某种方法可以对 JSON 进行排序或对我的语法进行短语化，以便在任何一种情况下都能找到县？

更新

这是神奇的 GREL，它允许我按名称查找 JSON 字符串中的元素，而不仅仅是位置：

filter(value.parseJson()[0]["politics"], item, item["type"]=="admin6")[0]["name"]
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1 回答 1

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名为的字段politics是一个数组，您可以返回：

value.parseJson()[0]["politics"]

该数组的一个元素与县相关联（它的friendly_type字段为“县”）。因此，您需要过滤该politics字段以找到friendly_type属于县的字段，如下所示：

filter(value.parseJson()[0]["politics"], item, item["friendly_type"]=="county")

这将返回一个包含一个元素的数组。您想name从那个元素中取出该字段，因此您需要提取name第零个数组元素的 ，从而形成完整的表达式：

filter(value.parseJson()[0]["politics"], item, item["friendly_type"]=="county")[0]["name"]
于 2012-04-25T14:38:25.193 回答