如何排序您从.csv文件中排序的内容

Question

如何通过ID，然后按照PRICE，然后在可能的情况下按DATE对.csv文件进行唯一排序。下面是一个例子文件：

"Date","other","Id","other","Price" 
"01/01/2016","3","6452312546-232","a","4.5" 
"01/03/2016","1","4375623416-345","b","56.25" 
"01/03/2016","6","4375623416-345","c","0" 
"01/03/2016","5","4375623416-345","d","0" 
"02/01/2016","4","6452312546-232","e","34.21" 

我所要的输出通过ID排序第一，让一切由ID进行分组，然后一旦他们分组，按价格各组排序，然后排序现在按组中最近的日期按PRICE排序的组。所以我会得到这个作为输出：

"Date","other","Id","other","Price" 
"02/01/2016","4","6452312546-232","e","34.21" 
"01/01/2016","3","6452312546-232","a","4.5" 
"01/03/2016","1","4375623416-345","b","56.25" 
"01/03/2016","6","4375623416-345","c","0" 
"01/03/2016","5","4375623416-345","d","0" 

这是明确的吗？让我知道如果它不是。

Answer 1

假设这个CSV文件足够小，可以安全地加载到内存中，您可以将文件读入散列并从中进行排序。

require 'csv' 

table = CSV.read('file.csv', headers: true).map { |row| Hash[row] } 
table.sort_by { |k, _| [k["id"], k["price"].to_f, Date.parse(k["date"])] } 

虽然，如果您最初按照ID进行排序，您将失去价格和日期字段的更细粒度。