[英]Python itertools.groupby multiple values
我有从数据库返回的记录,如下所示:
region month_taken total_att num_classes
Colorado 2013-01-01 00:00:00.000 78485 4648
Colorado 2013-02-01 00:00:00.000 71769 4162
Midwest 2013-01-01 00:00:00.000 110508 7101
Midwest 2013-02-01 00:00:00.000 103545 6410
我正在尝试将它们按如下方式放入列表中:
Total_att:
[{"data": [78485, 71769], "name": "Colorado"}, {"data": [110508, 103545], "name": "Midwest"}]
num_classes:
[{"data": [4648, 4162], "name": "Colorado"}, {"data": [7101, 6410], "name": "Midwest"}]
我发现了itertools.groupby可以满足我的要求,但是我很难用一个以上的值列表来完成它(因为缺少更好的术语)。
totalResults = []
for key, location in groupby(rows, lambda k: k[0]):
totalRow = dict()
totalRow['name'] = key
totalRow['data'] = [x[2] for x in location]
totalResults.append(totalRow)
太好了,这使我获得了total_att列表,但是随后我又进行了一个完整的groupby循环来创建“ num_classes”列表,这似乎很荒谬。 我在文档中看到了这一点,但老实说,如果我将其转换为列表,我不太确定这意味着什么或如何处理我的问题:
The returned group is itself an iterator that shares the underlying iterable with groupby(). Because the source is shared, when the groupby() object is advanced, the previous group is no longer visible. So, if that data is needed later, it should be stored as a list:
因此,如何在不对groupby(rows,lambda k:k [0]):中的键,位置进行多次处理的情况下创建列表?
我希望这一点很清楚,但很高兴在必要时提供更多信息。
totalResults = []
totalClasses = []
for key, location in groupby(rows, lambda k: k[0]):
location = list(location)
totalResults.append(dict(name=key, data=[x[2] for x in location]))
totalClasses.append(dict(name=key, data=[x[3] for x in location]))
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