Ruby same element array or value in hash , unite it,

Question

today I've got a very difficult task from my senior(perhaps it difficult only for me).

The task is like this:

He give me several string data(to be precise 8 string data). I can choose to store it in array or a hash.
```
"hello", "you", "great", "you", "great", "hello", "great", "great"
```
Now I must combine the same data from those strings. I mean if I put them inside an array.
```
myary = ["hello", "you", "great", "you", "great", "hello", "great", "great"]
```
I must make it become like this
```
myary = ["hello x2", "you x2', great x4"] # I need to append "x" and a variable indicating the total sum of every same string in the array.
```
I can use hash if I want, but the problem is, I can't find a good way to do this. I have struggle for several hours and it's futile. The best I can done is here:

I store them in a hash.

myhash = {

1 => "hello",
2 =>  "you",
3 => "great",
4 => "you",
5 => "great",
6 => "hello",
7 => "great",
8 => "great",
 }

Then I write this code:

 myarray = []

@variable = 0
for i in 1..myhash.length
  for j in 1..myhash.length
    @variable += 1 if myhash[i] == myhash[j]
  end
  myarray[i] = myhash[i]  << " x#{@variable}"
 @variable = 0
end

puts myarray

This will give the output:

hello x2    # This nice "hello" is 2 
you x2      # This good "you" indeed is 2
great x4    # This perfect "great" is 4          <= Everything great 'till here. But...
you x1      # Why?        
great x3    # What the..?
hello x1    # Oh c'mon..
great x2    # Okay, I'm screwed
great x1    # Stackoverflow help me!!

As you can see I'm screwed, I know the code is wrong, but believe me I nearly bang my head onto the wall because this matter. Someone please, I need serious help. Oh I want to make sure something, does the task is possible to accomplish or not? I just want to make sure that my senior is not teasing me with the task. But in fact I want to know if this really possible. Sorry if I've done something wrong. Thank you very much. Please no flaming :) After all I just asking, if you feel didn't like to give answer or else, then simply leave. Positive answer very appreciated.

Sergio Tulentsev · Accepted Answer · 2014-07-17 11:09:19Z

4

You almost never need low-level for loops in ruby.

myary = ["hello", "you", "great", "you", "great", "hello", "great", "great"]

myary.group_by{|el| el }.map {|key, items| "#{key} x#{items.length}"} # => ["hello x2", "you x2", "great x4"]

Documentation: Enumerable#group_by, Enumerable#map.

answered Jul 17, 2014 at 11:09

Sergio Tulentsev

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1 Comment

LuminaChen Over a year ago

Woaah, this is really great, I never know group_by method before. Thank you so much. :)

Neil Smith · Accepted Answer · 2014-07-17 14:32:16Z

1

You could also use a hash, where the key is the word and the value is the number of times you've seen it. The first time you see a word, add it to the hash with a count of 1. If you see it again, change the value stored in the hash for that word.

When you've finished, look up the counts in the hash.

(I'm not saying any more as this looks like a homework problem. Ask your teacher to explain this if you're stuck.)

answered Jul 17, 2014 at 14:32

Neil Smith

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Cary Swoveland Over a year ago

As a few days have now passed, perhaps another nudge is justified. Convert your array of words to an array of hashes, each hash having a single key (a word in the array) and a value of 1. Now, in turn, merge these hashes into an initially-empty hash, using the form of Hash.merge that takes a block.

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