我正在尝试建立一个系统,该系统将根据提供的项目数量和有多少行打印一定数量的页面。
我基本上有一个包含几个字段的 map 列表,其中包括一个可能很长并且跨越打印机上的多行的名称字段。我有一个函数可以识别它将占用多少行,所以这不是问题。
主要问题是我想在产品集合达到 30 行时对其进行拆分(好吧,分区,如果您使用 clojure 的术语),这样我就可以开始另一个页面。有没有办法遍历集合,计算出总行数最多为 30 行(如果存在多行产品,否则会超过 30 行,则行数会更少),然后将其拆分?
我想转这个
[{:qty 2 :size "M" :product "Testing 1 2 3"}
{:qty 1 :size "S" :product "Hello there world"}
{:qty 12 :size "XS" :product "Some really long product name just to test"}
{:qty 932 :size "L" :product "More longer names to play with"}
{:qty 1 :size "M" :product "Another product name"}
{:qty 1242 :size "XS" :product "This is just an obscenely long product name that I am hoping will spill over on to the next lines"}
{:qty 2 :size "M" :product "Testing 1 2 3"}
{:qty 1 :size "S" :product "Hello there world"}
{:qty 12 :size "XS" :product "Some really long product name just to test"}
{:qty 932 :size "L" :product "More longer names to play with"}
{:qty 1 :size "M" :product "Another product name"}
{:qty 1242 :size "XS" :product "This is just an obscenely long product name that I am hoping will spill over on to the next lines"}
{:qty 2 :size "M" :product "Testing 1 2 3"}
{:qty 1 :size "S" :product "Hello there world"}
{:qty 12 :size "XS" :product "Some really long product name just to test"}
{:qty 932 :size "L" :product "More longer names to play with"}
{:qty 1 :size "M" :product "Another product name"}
{:qty 1242 :size "XS" :product "This is just an obscenely long product name that I am hoping will spill over on to the next lines"}]
进入此
[[{:qty 2 :size "M" :product "Testing 1 2 3"}
{:qty 1 :size "S" :product "Hello there world"}
{:qty 12 :size "XS" :product "Some really long product name just to test"}
{:qty 932 :size "L" :product "More longer names to play with"}
{:qty 1 :size "M" :product "Another product name"}
{:qty 1242 :size "XS" :product "This is just an obscenely long product name that I am hoping will spill over on to the next lines"}
{:qty 2 :size "M" :product "Testing 1 2 3"}
{:qty 1 :size "S" :product "Hello there world"}
{:qty 12 :size "XS" :product "Some really long product name just to test"}
{:qty 932 :size "L" :product "More longer names to play with"}
{:qty 1 :size "M" :product "Another product name"}]
[{:qty 1242 :size "XS" :product "This is just an obscenely long product name that I am hoping will spill over on to the next lines"}
{:qty 2 :size "M" :product "Testing 1 2 3"}
{:qty 1 :size "S" :product "Hello there world"}
{:qty 12 :size "XS" :product "Some really long product name just to test"}
{:qty 932 :size "L" :product "More longer names to play with"}
{:qty 1 :size "M" :product "Another product name"}
{:qty 1242 :size "XS" :product "This is just an obscenely long product name that I am hoping will spill over on to the next lines"}]]
产品名称的最大行长度为 25 个字符
提前致谢!
最佳答案
我将为您提供类似问题的答案,您应该能够从那里推断出您问题的答案。
问题:
如何将字符串序列分组为相邻字符串的子组,每个子组中总共最多有 n 个字符?
解决方案:
;; Data
(def input
["asdjasjdklasj" "dkjfsj" "dfkjsj" "kfjskd" "skdjfsjkdjdfs"
"dfjskd" "wiuennsdw" "dskjdfsdjwed" "wiuf" "mncxnejs" "fjsjd"
"dkjsf" "djsk" "djf" "erjfdkjcxzasd" "sjkja"])
;; Counting function
(def char-count count)
;; Partition function
(defn group-to-size [size coll]
(lazy-seq
(loop [[x & xs' :as xs] coll, n 0, acc []]
(if (nil? x) (cons acc nil)
(let [n' (+ n (char-count x))]
(if (<= n' size)
(recur xs' n' (conj acc x))
(cons acc (group-to-size size xs))))))))
;; Sample grouping by 15 characters
(group-to-size 15 input)
; => (["asdjasjdklasj"]
; ["dkjfsj" "dfkjsj"]
; ["kfjskd"]
; ["skdjfsjkdjdfs"]
; ["dfjskd" "wiuennsdw"]
; ["dskjdfsdjwed"]
; ["wiuf" "mncxnejs"]
; ["fjsjd" "dkjsf" "djsk"]
; ["djf"]
; ["erjfdkjcxzasd"]
; ["sjkja"])
;; Resulting character counts per group for the above sample
(->> (group-to-size 15 input)
(map (comp count (partial apply concat))))
; => (13 12 6 13 15 12 12 14 3 13 5)
您想要计算产品描述中的行数,而不是计算字符串中的字符数。用于计算每个产品的行数的函数相当于上面代码中的 char-count
。我想你应该能够从这里弄清楚。
注意:此解决方案还有一个额外的好处:懒。这意味着如果您最终只想使用第一个分区,则不必对整个字符串集进行分区。在您的情况下,如果用户决定仅查看前几页,则不会对整个库存进行分区。
关于clojure - 根据 clojure 中的映射值拆分映射集合,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/13079475/