如何对从.csv文件中排序的内容进行排序

Question

我如何通过ID然后按PRICE对.csv文件进行唯一排序，然后，如果可能，由DATE进行排序。这是一个示例文件：

"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"

我希望输出首先按ID排序，以便所有内容先按ID分组，然后将它们分组后，按PRICE对各个组进行排序，然后按最近的日期对现在的PRICE排序组进行排序群组。所以我把它作为输出：

"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"

这是清楚的吗？如果不是，请告诉我。

Answer 1

假设此CSV文件足够小以便可以安全地加载到内存中，您可以将文件读入哈希并从那里对其进行排序。

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ID进行排序，那么您将失去价格和日期字段的任何粒度。