Ruby on Rails字段平均值？ [英] Ruby on Rails field average?

问题描述

有一个简单的方法来获取集合中属性的平均值吗？

Is there an easy way to obtain the average of an attribute in a collection?

例如，每个用户都有一个分数。

For instance, each user has a score.

给定一个用户集合（@users），如何获得该组的平均分数？

Given a collection of user(s) (@users), how can you get the average score for the group?

有什么像@ users.average（：score）？我想我为数据库字段遇到类似这样的东西，但我需要它为一个集合工作

Is there anything like @users.average(:score)? I think I came across something like this for database fields, but I need it to work for a collection...

推荐答案

你的问题，实际上可以做：

For your question, one could actually do:

@users.collect(&:score).sum.to_f/@users.length if @users.length > 0

早些时候我想，@ users.collect（&：score）。对于数据库字段，User.average（：score）将工作。您还可以添加：条件，如其他activerecord查询。

Earlier I thought, @users.collect(&:score).average would have worked. For database fields, User.average(:score) will work. You can also add :conditions like other activerecord queries.

这篇关于Ruby on Rails字段平均值？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！