LocalJumpError calculating the median

rubyonrails-talk
1

Hi

I have searched/Googled around but I'm struggling with the following problem.

I am building a Rails 2.3.2 application and one of the requirements is to calculate the median of an array of results. I am using code for calculating the median from the Ruby Cookbook but keep running in to a problem with receiving an error 'LocalJumpError - no block given' when I attempt to find the median of an array where there are an odd number of members.

The example code in my view is as follows:

<%= survey_response.median([6,4,5,4,4,2]) %> Then in survey_response.rb model the methods are as follows:

def mean(array)   array.inject(array.inject(0) { |sum, x| sum += x } / array.size.to_f) end

def median(array,already_sorted=false)   return nil if array.empty?   array = array.sort unless already_sorted   m_pos = array.size / 2   return array.size % 2 == 1 ? array[m_pos] : mean(array [m_pos-1..m_pos]) end

The error is caused when the median method refers back to the mean method to get the media of an odd total of items in the array. I just can't figure out why I get that error or indeed how to fix it - so I'd hugely appreciate any help/guidance/laughing anybody could offer me!

Thanks

Simon

2

The example code in my view is as follows:

<%= survey_response.median([6,4,5,4,4,2]) %> Then in survey_response.rb model the methods are as follows:

def mean(array) array.inject(array.inject(0) { |sum, x| sum += x } / array.size.to_f) end

You've got two calls to inject there, but only the inner one has a block. Not sure what the second call to inject should be doing - i don't think you need it at all.

Fred