Sorting multidimensional array, descending

Question

I have an multidimensional array in my ruby which looks like this :

arr= [{"10.0.1.50", "4"},
      {"10.0.1.51", "10"},
      {"10.0.1.48", "7"}]

I want to sort it such that the result should be:

result= [{"10.0.1.51", "10"},
         {"10.0.1.50", "4"},
         {"10.0.1.48", "7"}]

I am basically sorting on the first column which is 10.0.1.X. So it is sorted based on X.

Are you sorting based on left side "10.0.1.51" or right side "10" — Jason Kim
– Jason Kim, Commented Apr 24, 2013 at 22:45
@garbagecollection : The first column.....I just edited the post — Pi Horse
– Pi Horse, Commented Apr 24, 2013 at 22:52

Niklas B. · Accepted Answer · 2013-04-24 22:56:39Z

4

The syntax is not Ruby and the result is a bit ambiguous, but I guess you want something along the lines of

arr.sort_by { |(x,_)| x.split(".").map(&:to_i) }.reverse!

edited Apr 24, 2013 at 22:56

answered Apr 24, 2013 at 22:48

Niklas B.

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8 Comments

Pi Horse Over a year ago

This does not work as the first column (10.0.1.X) is considered as a string. Is there any way I can convert that to float? If i do (.to_f) it will convert it to 10.0 ignoring everything else after it.

Niklas B. Over a year ago

@sagar: You need to specify what order it is that you want to use for sorting. I'm guessing lexicographically, interpreting the dot-separated blocks as numbers? You wouldn't have these problems if you'd represent the IP addresses as what they are, 32-bit integers

Pi Horse Over a year ago

It says : undefined method `to_i' for ["10.0.1.50"]:Array

Niklas B. Over a year ago

@sogar: What's arr? I'm assuming arr = [["10.0.1.50", "4"],["10.0.1.51", "10"],["10.0.1.48", "7"]]. I don't see where the ["10.0.1.50"] is coming from. Since your example code is no valid Ruby (Ruby has no syntax element of the form {a_1,a_2,...,a_n}) we can only guess.

Pi Horse Over a year ago

arr_tmp = $connection.execute("select code_ver from builds;") arr = Array.new arr = arr_tmp.inject(Hash.new(0)) { |hash,element| hash[element] +=1 hash }

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