python 分组不工作

Question

我有一个字典列表，我想按字符串类型的字段对它们进行分组

recs = [
    {'r_date': datetime.date(2014, 1, 1), 'r_time_start': datetime.time(7, 0), 'r_item1_name': 'Sef', 'r_time_end': datetime.time(12, 0)}, 
    {'r_date': datetime.date(2014, 1, 1), 'r_time_start': datetime.time(8, 0), 'r_item1_name': 'Moj\xc4\x8dca', 'r_time_end': datetime.time(15, 0)}, 
    {'r_date': datetime.date(2014, 1, 1), 'r_time_start': datetime.time(9, 0), 'r_item1_name': 'Student1', 'r_time_end': datetime.time(19, 0)}, 
    {'r_date': datetime.date(2014, 1, 1), 'r_time_start': datetime.time(12, 0), 'r_item1_name': 'Student2', 'r_time_end': datetime.time(19, 0)},
    {'r_date': datetime.date(2014, 1, 2), 'r_time_start': datetime.time(7, 0), 'r_item1_name': 'Sef', 'r_time_end': datetime.time(12, 0)},
    {'r_date': datetime.date(2014, 1, 2), 'r_time_start': datetime.time(8, 0), 'r_item1_name': 'Moj\xc4\x8dca', 'r_time_end': datetime.time(15, 0)},
    {'r_date': datetime.date(2014, 1, 2), 'r_time_start': datetime.time(9, 0), 'r_item1_name': 'Student1', 'r_time_end': datetime.time(19, 0)},
    {'r_date': datetime.date(2014, 1, 2), 'r_time_start': datetime.time(12, 0), 'r_item1_name': 'Student2', 'r_time_end': datetime.time(19, 0)},
    {'r_date': datetime.date(2014, 1, 3), 'r_time_start': datetime.time(7, 0), 'r_item1_name': 'Sef', 'r_time_end': datetime.time(12, 0)},
    {'r_date': datetime.date(2014, 1, 3), 'r_time_start': datetime.time(8, 0), 'r_item1_name': 'Moj\xc4\x8dca', 'r_time_end': datetime.time(15, 0)},
    {'r_date': datetime.date(2014, 1, 3), 'r_time_start': datetime.time(9, 0), 'r_item1_name': 'Student1', 'r_time_end': datetime.time(19, 0)},
    {'r_date': datetime.date(2014, 1, 3), 'r_time_start': datetime.time(12, 0), 'r_item1_name': 'Student2', 'r_time_end': datetime.time(19, 0)},
    {'r_date': datetime.date(2014, 1, 4), 'r_time_start': datetime.time(7, 0), 'r_item1_name': 'Sef', 'r_time_end': datetime.time(12, 0)},
    {'r_date': datetime.date(2014, 1, 4), 'r_time_start': datetime.time(8, 0), 'r_item1_name': 'Moj\xc4\x8dca', 'r_time_end': datetime.time(15, 0)},
    {'r_date': datetime.date(2014, 1, 4), 'r_time_start': datetime.time(9, 0), 'r_item1_name': 'Student1', 'r_time_end': datetime.time(19, 0)},
    {'r_date': datetime.date(2014, 1, 4), 'r_time_start': datetime.time(14, 0), 'r_item1_name': 'Namestnik', 'r_time_end': datetime.time(22, 0)},
    {'r_date': datetime.date(2014, 1, 5), 'r_time_start': datetime.time(7, 0), 'r_item1_name': 'Sef', 'r_time_end': datetime.time(12, 0)},
    {'r_date': datetime.date(2014, 1, 5), 'r_time_start': datetime.time(8, 0), 'r_item1_name': 'Moj\xc4\x8dca', 'r_time_end': datetime.time(15, 0)},
    {'r_date': datetime.date(2014, 1, 5), 'r_time_start': datetime.time(9, 0), 'r_item1_name': 'Student1', 'r_time_end': datetime.time(19, 0)},
    {'r_date': datetime.date(2014, 1, 5), 'r_time_start': datetime.time(14, 0), 'r_item1_name': 'Namestnik', 'r_time_end': datetime.time(22, 0)},
    {'r_date': datetime.date(2014, 1, 6), 'r_time_start': datetime.time(7, 0), 'r_item1_name': 'Sef', 'r_time_end': datetime.time(12, 0)},
    {'r_date': datetime.date(2014, 1, 6), 'r_time_start': datetime.time(8, 0), 'r_item1_name': 'Moj\xc4\x8dca', 'r_time_end': datetime.time(15, 0)},
    {'r_date': datetime.date(2014, 1, 6), 'r_time_start': datetime.time(9, 0), 'r_item1_name': 'Student1', 'r_time_end': datetime.time(19, 0)},
    {'r_date': datetime.date(2014, 1, 6), 'r_time_start': datetime.time(14, 0), 'r_item1_name': 'Namestnik', 'r_time_end': datetime.time(22, 0)}]

我想获取按 r_item1_name

分组的字典列表

grouped = [{"r_item1_name": "Sef","AllData" : [{record_of_sef},{another_record_of_sef},{another_record_of_sef}] }]

 for key, items in itertools.groupby(recs, operator.itemgetter('r_item1_name')):
    grupirani1.append({"r_item1_name": key, "AllData": list(items)})

如果我按日期类型 (r_date) 对代码组进行分组，则按预期进行。

知道为什么吗？

Answer 1

itertools.groupby 要求输入数据已经按用于分组的键排序。只有具有相同键的连续值才会被分组，因此如果数据未排序，您将为具有相同值的每个块获得单独的组。

我重新格式化了您问题中的数据，以便可以查看各个项目。现在应该清楚它是按 r_date 排序的，因此分组将在该字段上起作用，但您需要对其进行排序以在任何其他字段上分组。

python 分组不工作

python group by not working

python

grouping

dictionary

group-by