Ruby数组注入
我试图通过使用inject方法记录10个线程的平均运行时间，但它给了我这个错误：
undefined method `+' for # (NoMethodError) from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/open-uri.rb:301:in `inject' from client_test.rb:13:in `each' from client_test.rb:13:in `inject' from client_test.rb:13 这是代码：
require 'open-uri' program_start_time = Time.now threads = 10.times.map do Thread.new do time = Time.now open('http://ca.yahoo.com/?p=us').read.length Time.now-time end end threads.map &:join puts threads.inject() { |sum, e| sum + e.value}.to_f / threads.size puts Time.now - program_start_time
在这种情况下，您需要为inject提供初始值，因为如果不这样做，初始值只是数组中的第一个元素：
puts threads.inject(0) { |sum, e| sum + e.value}.to_f / threads.size
您没有提供总和的初始值
threads.inject() { |sum, e| sum + e.value}.to_f / threads.size
修复它
threads.inject(0) { |sum, e| sum + e.value}.to_f / threads.size