更新多个键的值

本文介绍了更新多个键的值的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

如果您有地图或地图集合，并且想要使用一个函数更新多个键的值，最方便的方式是什么？

If you have a map or a collection of maps and you'd like to be able to update the values of several keys with one function, what the the most idiomatic way of doing this?

=> (def m [{:a 2 :b 3} {:a 2 :b 5}]) #'user/m => (map #(update-in % [:a] inc) m) ({:a 3, :b 3} {:a 3, :b 5})

我不想映射每个键的更新，我理想地喜欢一些操作如下的函数：

Rather than mapping update-in for each key, I'd ideally like some function that operates like this:

=> (map #(update-vals % [:a :b] inc) m) ({:a 3, :b 4} {:a 3, :b 6})

任何建议都非常感谢！我试图减少不必要的长脚本中的行数。

Any advice would be much appreciated! I'm trying to reduce the number of lines in an unnecessarily long script.

推荐答案

每当你需要迭代应用fn一些数据 reduce 是您的朋友：

Whenever you need to iteratively apply a fn to some data, reduce is your friend:

(defn update-vals [map vals f] (reduce #(update-in % [%2] f) map vals))

b $ b

这里是操作中：

Here it is in action:

user> (def m1 {:a 2 :b 3}) #'user/m1 user> (update-vals m1 [:a :b] inc) {:a 3, :b 4} user> (def m [{:a 2 :b 3} {:a 2 :b 5}]) #'user/m user> (map #(update-vals % [:a :b] inc) m) ({:a 3, :b 4} {:a 3, :b 6})