如何最好地将CSV中的数据存储在Java类中?是Row对象的单个列表，还是带有嵌套对象的单个对象? [英] How to best store data from CSV in java class? A single list of Row objects, or a single object with nested objects?
问题描述
Date,Locality,District,New Cases,Hospitalizations,Deaths
5/21/2020,Accomack,Eastern Shore,709,40,11
5/21/2020,Albemarle,Thomas Jefferson,142,19,4
5/21/2020,Alleghany,Alleghany,9,4,0
5/21/2020,Amelia,Piedmont,22,7,1
5/21/2020,Amherst,Central Virginia,25,3,0
5/21/2020,Appomattox,Central Virginia,25,1,0
5/21/2020,Arlington,Arlington,1763,346,89
... // skipped down to the next day
5/20/2020,Accomack,Eastern Shore,709,39,11
5/20/2020,Albemarle,Thomas Jefferson,142,18,4
5/20/2020,Alleghany,Alleghany,10,4,0
5/20/2020,Amelia,Piedmont,21,7,1
5/20/2020,Amherst,Central Virginia,25,3,0
5/20/2020,Appomattox,Central Virginia,24,1,0
5/20/2020,Arlington,Arlington,1728,334,81
5/20/2020,Augusta,Central Shenandoah,88,4,1
... // continued
我像上面的CSV一样在美国拥有一个州的数据，并希望对其进行一些数据分析，以便可以通过rest API发送该数据.我要进行的数据分析是各种汇总，例如:各州按日期划分的总病例数，整个州的总病例数，按地区分组的总病例数，按日期划分的一个地区的总病例数，一个县的总病例数按日期等.可以使用此数据进行的所有基本分组依据.
I have data for a State in the US like the above in a CSV and would like to do some data analysis on it so that I can send it through a rest API. The data analysis that I would like to do are various aggregations, such as: total cases across the state by date, total cases for the entire state , total cases grouped by district, total cases for a district by date, total cases for a county by date, etc. Just all the basic groupby's that one could do with this data.
现在，我的问题是弄清楚如何在没有数据库的情况下将数据正确存储在java中.我有一个使用Row对象列表的成功实现，其中每个Row对象在CSV中仅包含一行.然后，使用Java的Stream api，我已经能够过滤并获取其中一些统计信息.然后，我将这些统计信息打包到单个Row对象或List<Row>中，并将其发送到API以解析为JSON.这行得通，但是我觉得这不是最好的方法.
还有其他一些更多的面向对象的方法来利用Date，District，County，Cases列.
Now, my problem is figuring out how to properly store this data in java, without a database. I have one successful implementation using a list of Row objects, where each Row object contains just one row in the CSV. Then using java's Stream api I have been able to filter and get some of these statistics. I then package these statistics into a single Row object or a List<Row> and send it to the API to be parsed into JSON. This has worked ok, but I feel that this is not the best way.
Is there some other more object-oriented way to utilize the Date, District, County, Cases column.
我正在考虑做这样的事情:
I was thinking of doing something like this :
class State {
List<District> districtList;
String name;
}
class District {
List<County> countyList;
String name;
}
class County {
LocalDate date;
String name;
int cases;
// more stuff
}
然后，我将创建一个State对象，其中包含District个对象的列表，每个对象都包含许多County个对象的列表，每个日期一个.
Then I would create one State object with a list of District objects, each with a list of many County objects, one per date.
这看起来像是过分杀伤力了吗?还有其他一些干净的方法可以将此数据集读入数据结构，以便轻松汇总摘要信息.
Does this seem like overkill? Is there some other clean way to read this dataset into a data structure that allows for easily aggregating summary information.
我目前的操作方式现在可以使用，但我正在寻找更好的方法！
The way that I'm currently doing it now works, but I am looking for a better way!
推荐答案
从您的描述来看，您的方法听起来不错，而且是正确的面向对象的.但是，如果没有其他信息(例如，可能以其他方式指示的特定汇总)，您在区域"对象中会有多个重复"的县"对象似乎很奇怪.例如:
From your description, your approach seems sound, and properly object-oriented. However, without additional information (e.g. specific aggregations which may dictate otherwise), it seems odd you would have multiple "duplicate" 'County' objects in your District objects. For example:
[{"date":"5/21/2020","name":"Accomack"},
{"date":"5/20/2020","name":"Accomack"}]
从面向对象的角度来看，您似乎希望按日期"(每个日期包含县"行列表)进行附加的汇总.
From an object-oriented view, it seems you'd want an additional level of aggregation, by "Date" (with each date containing a list of 'County' rows).
一个考虑:如果您的聚合与数据库方法更好地匹配，我认为应该保留源数据中的每一行并查询AS/IS，并通过Stream lambda对其进行过滤和排序.
One consideration: if your aggregations align better with a database approach, I would think each row from the source data should be kept and queried AS/IS, filtered and sorted via Stream lambdas.
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