如何获得一个clojure数组映射来保持assoc之后的插入顺序？ [英] How to get a clojure array-map to maintain insertion order after assoc?

问题描述

我有一个 array-map ，它是 assoc 一些值。在一定大小后，返回的值是 PersistentHashMap ，而不是原始的 PersistentArrayMap 。我在几个网站上阅读过这种行为。有什么办法强制插入订单，即使在 assoc ？

之后，我确实有一个单独的函数一个 ash-map 和一个键的向量，并按顺序返回一个新鲜的 array-map 键，但这意味着对于每个关联，我必须首先提取关键字，将新关键字用于向量，然后创建一个新的数组映射。似乎kludgey，即使写在一个单独的函数。

是否有一个更直接的语言支持的方式来保持插入顺序，即使在大型（> 10，但< ; 50）keys array-map？

在相关的情况下，我使用数组映射列表作为incanter数据集中的数据，然后输出为excel。 save-xls函数保持键/列的顺序。

谢谢

解决方案

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您可以使用有序地图： https://github.com/flatland/ordered

I have an array-map which I am associng some values into it. After a certain size the returned value is a PersistentHashMap rather than the original PersistentArrayMap. I've read about this behavior on a few web sites. Is there any way to force the insertion order even after assoc?

I do have a separate function which will take a ash-map and a vector of keys, and return a "fresh" array-map with keys in this order, but it means that for each assoc, I have to extract the keys first, cons/conj the new key to the vector, then create a new array-map. Seems kludgey, even if written in a separate function.

Is there a more direct language-supported way of keeping insertion order even on large-ish (>10, but < 50) keys array-map?

In case it's relevant, I'm using a list of array-maps as data into an incanter dataset and then outputting to excel. The save-xls function keeps the order of the keys/columns.

Thanks

解决方案

You can use an ordered map: https://github.com/flatland/ordered

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