Clojure 排序依据

Question

我正在尝试越来越多地了解 Clojure，我有以下列表：

{merchant-data {order-id 72144305, unit-price-dollars 110.0, merchant-discount-dollars 20.5, my-discount-dollars 10.2, session-type CONTROL}, my-data {order-id 72144305, unit-price-dollars 110.5, merchant-discount-dollars 10.0, my-discount-dollars 20.2, session-type control}}
{merchant-data {order-id 72144777, unit-price-dollars 200.0, merchant-discount-dollars 30.0, my-discount-dollars 0.0, session-type TEST}, my-data {order-id 72144777, unit-price-dollars 200.0, merchant-discount-dollars 0.0, my-discount-dollars 30.0, session-type test}}
{merchant-data {order-id 72145239, unit-price-dollars 50.0, merchant-discount-dollars 14.8, my-discount-dollars 2.0, session-type UNMANAGED}, my-data {order-id 72145239, unit-price-dollars 50.0, merchant-discount-dollars 5.0, my-discount-dollars 15.0, session-type unmanaged}}

我正在尝试根据特定字段对此列表进行排序，例如（单价美元）：

（排序方式：单位价格美元排序结果）

出于某种原因，我没有得到排序列表，请帮忙！如果这不是正确的方法，请提出正确的方法！

Answer 1

首先，如果您尝试排序的数据结构是有效的 Clojure，它总是有帮助的。其次，您需要指定要作为排序依据的值的完整路径。

user> (def prices [{:merchant-data {:order-id 72144305, :unit-price-dollars 110.0, :merchant-discount-dollars 20.5, :my-discount-dollars 10.2, :session-type "CONTROL"}, :my-data {:order-id 72144305, :unit-price-dollars 110.5, :merchant-discount-dollars 10.0, :my-discount-dollars 20.2, :session-type "control"}}
{:merchant-data {:order-id 72144777, :unit-price-dollars 200.0, :merchant-discount-dollars 30.0, :my-discount-dollars 0.0, :session-type "TEST"}, :my-data {:order-id 72144777, :unit-price-dollars 200.0, :merchant-discount-dollars 0.0, :my-discount-dollars 30.0, :session-type "test"}}
{:merchant-data {:order-id 72145239, :unit-price-dollars 50.0, :merchant-discount-dollars 14.8, :my-discount-dollars 2.0, :session-type "UNMANAGED"}, :my-data {:order-id 72145239, :unit-price-dollars 50.0, :merchant-discount-dollars 5.0, :my-discount-dollars 15.0, :session-type "unmanaged"}}])

user> (clojure.pprint/pprint (sort-by #(get-in % [:merchant-data :unit-price-dollars]) prices))
({:my-data
  {:my-discount-dollars 15.0,
   :unit-price-dollars 50.0,
   :session-type "unmanaged",
   :order-id 72145239,
   :merchant-discount-dollars 5.0},
  :merchant-data
  {:my-discount-dollars 2.0,
   :unit-price-dollars 50.0,
   :session-type "UNMANAGED",
   :order-id 72145239,
   :merchant-discount-dollars 14.8}}
 {:my-data
  {:my-discount-dollars 20.2,
   :unit-price-dollars 110.5,
   :session-type "control",
   :order-id 72144305,
   :merchant-discount-dollars 10.0},
  :merchant-data
  {:my-discount-dollars 10.2,
   :unit-price-dollars 110.0,
   :session-type "CONTROL",
   :order-id 72144305,
   :merchant-discount-dollars 20.5}}
 {:my-data
  {:my-discount-dollars 30.0,
   :unit-price-dollars 200.0,
   :session-type "test",
   :order-id 72144777,
   :merchant-discount-dollars 0.0},
  :merchant-data
  {:my-discount-dollars 0.0,
   :unit-price-dollars 200.0,
   :session-type "TEST",
   :order-id 72144777,
   :merchant-discount-dollars 30.0}})
nil

Answer 2

问题本身就有问题。例如，上面的地图不包含 unit-price-dollars 但它们的两个子地图包含。您要按商家数据、我的数据还是两者的某种组合排序？

尝试更简单的情况，按其中一个值（随机选择的商家数据）排序，将所有符号键转换为关键字，并将各个映射放入一个集合中得到：

(def test-data
  [{:merchant-data {:order-id 72144305, :unit-price-dollars 110.0, :merchant-discount-dollars 20.5, :my-discount-dollars 10.2, :session-type :CONTROL}, :my-data {:order-id 72144305, :unit-price-dollars 110.5, :merchant-discount-dollars 10.0, :my-discount-dollars 20.2, :session-type :control}}
   {:merchant-data {:order-id 72144777, :unit-price-dollars 200.0, :merchant-discount-dollars 30.0, :my-discount-dollars 0.0, :session-type :TEST}, :my-data {:order-id 72144777, :unit-price-dollars 200.0, :merchant-discount-dollars 0.0, :my-discount-dollars 30.0, :session-type :test}}
   {:merchant-data {:order-id 72145239, :unit-price-dollars 50.0, :merchant-discount-dollars 14.8, :my-discount-dollars 2.0, :session-type :UNMANAGED}, :my-data {:order-id 72145239, :unit-price-dollars 50.0, :merchant-discount-dollars 5.0, :my-discount-dollars 15.0, :session-type :unmanaged}}])

(sort-by (comp :merchant-data :unit-price-dollars) test-data)

; =>
;({:merchant-data {:order-id 72145239, :unit-price-dollars 50.0, :merchant-discount-dollars 14.8, :my-discount-dollars 2.0, :session-type :UNMANAGED}, :my-data {:order-id 72145239, :unit-price-dollars 50.0, :merchant-discount-dollars 5.0, :my-discount-dollars 15.0, :session-type :unmanaged}}
; {:merchant-data {:order-id 72144305, :unit-price-dollars 110.0, :merchant-discount-dollars 20.5, :my-discount-dollars 10.2, :session-type :CONTROL}, :my-data {:order-id 72144305, :unit-price-dollars 110.5, :merchant-discount-dollars 10.0, :my-discount-dollars 20.2, :session-type :control}}
; {:merchant-data {:order-id 72144777, :unit-price-dollars 200.0, :merchant-discount-dollars 30.0, :my-discount-dollars 0.0, :session-type :TEST}, :my-data {:order-id 72144777, :unit-price-dollars 200.0, :merchant-discount-dollars 0.0, :my-discount-dollars 30.0, :session-type :test}})

如果这不是您想要的，那么您将不得不让您的问题更清楚。

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