Question

我有一个矢量矢量，我想将它们分成单独的矢量。

<div>
<% @hosts.each do |host| %>
  <div class="row">
    <% if host.rooms.any? { |room| room.bookings.empty? } %>
      <!-- if a host has rooms without bookings then they are definitely going to have free rooms -->
      <div class="small-3 medium-4 large-4 columns">
        <%= image_tag host.picture_url %>
      </div>
      <div class="small-9 medium-8 large-8 columns">
        <p>Host #<%= host.id %>: <%= host.name %></p>
        <p><%= host.address %></p>
        <% host.rooms.each do |room| %>
          <!-- display information on free rooms -->
          <% if room.bookings.empty? %>
            <p>room #<%= room.id %> is available (0 booked, <%= room.capacity %> free out of <%= room.capacity %>)</p>
          <% else %>
            <!-- for the rooms with bookings - check if rooms are fully booked first -->
            <% unless ((room.capacity - room.bookings.first.number_of_guests) == 0) %>
              <% total_booked = room.bookings.first.number_of_guests %>
              <% space = room.capacity - total_booked %>
              <p>room #<%= room.id %> is available (<%= total_booked %> booked, <%= space %> free out of <%= room.capacity %>)</p>
            <% end %>
          <% end %>
        <% end %>
      </div>
    <% else %>
    <!-- if all the rooms belonging to a host are booked - check if all the rooms are fully booked -->
      <% if !(host.rooms.all? { |room| (room.capacity - room.bookings.first.number_of_guests) == 0 }) %>
        <!-- If all the rooms are fully booked there is nothing to display so there is no else block. Check the rooms individually for availability -->
        <div class="small-3 medium-4 large-4 columns">
          <%= image_tag host.picture_url %>
        </div>
        <div class="small-9 medium-8 large-4 columns">
          <p>Host #<%= host.id %>: <%= host.name %></p>
          <p><%= host.address %></p>
          <% host.rooms.each do |room| %>
            <% unless ((room.capacity - room.bookings.first.number_of_guests) == 0) %>
              <% total_booked = room.bookings.first.number_of_guests %>
              <% space = room.capacity - total_booked %>
              <p>room #<%= room.id %> is available (<%= total_booked %> booked, <%= space %> free out of <%= room.capacity %>)</p>
            <% end %>
          <% end %>
        </div>
      <% end %>
    <% end %>
  </div>
<% end %>
</div>

Answer 1

你的向量中已经有了单独的向量。存在多种访问方式，尤其是nth。

分离可以在很多方面发生。以下是您可以在REPL中尝试的一些示例。

一种常见的模式是使用let with在本地上下文中单独绑定它们：

(let [first-elem (nth my-vec 0)
      third-elem (nth my-vec 2)]
  (str "First: " first-elem "\Third: " third-elem))

这通常也是通过析构函数完成的：

(let [[first-elem _ third-elem] my-vec] ;; _ is idiomatic for ignored binding
  (str "First: " first-elem "\Third: " third-elem))

另一种常见情况是从各个元素构建一个惰性序列，例如：

(map-indexed (fn [i v] (str "Elem " i ": " v)) my-vec)

或只是迭代副作用

(doseq [v my-vec]
  (println v))
;; in Clojure 1.7 prefer
(run! println my-vec)

或将一个存储为可变状态

(def current-choice (atom nil))
(swap! current-choice (nth my-vec 2))
@current-choice

当您了解Clojure系列时，您会发现更多。随意继续实验。

将单个矢量矢量分成clojure中的单个矢量

1 个答案: