在Google Refine中解析JSON

Question

我正在尝试使用Google Refine从Data Science Toolkit coordinates2politics API中提取特定元素.

这是样本单元#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"}}]

我使用这个GREL语法添加了一个基于此专栏的专栏来推出该县,Dane:

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

但是当我进入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"}}]

有没有办法对JSON或短语我的语法进行排序,以便我可以在任何一种情况下找到该县？

更新

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

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

Answer 1

命名的字段politics是一个数组,您返回的是:

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

该数组的一个元素与县相关联(它的friendly_type字段是"县").所以你需要过滤该politics字段以找到一个friendly_type县,如下所示:

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

返回一个包含一个元素的数组.您希望name从该元素中获取该字段,因此您需要提取name第0个数组元素,使您的完整表达式:

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