# Question - looking for library to use for query like code?

**URL:** <https://www.ruby-forum.com/t/question-looking-for-library-to-use-for-query-like-code/159634>\
**Category:** Ruby\
**Created:** [February 6, 2009, 3:30pm UTC](https://www.ruby-forum.com/t/question-looking-for-library-to-use-for-query-like-code/159634 "2009-02-06T15:30:34Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![mmcolli00](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/85e7bf/32.png) [@mmcolli00](https://www.ruby-forum.com/u/mmcolli00)\
**Post date:** [February 6, 2009, 3:30pm UTC](https://www.ruby-forum.com/t/question-looking-for-library-to-use-for-query-like-code/159634/1 "2009-02-06T15:30:34Z")

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Can this be done with Ruby? (this may be a shot in the dark)

Say you have a text file with a lot of data and you want to group all of  
your data by a specific value. Is there a way to code something in ruby  
similar to a query that you would create using sql. Can this even be  
done using Ruby? And if so, is there a library that you can refer me to?  
If not, do you know any alternative ways? Thanks, MC

example of text:

auto, model  
car, honda  
truck, chevy  
car, nissan  
truck, toyota  
truck, ford

how i’d like it to look:

car, honda, nissan,  
truck, chevy, toyota, ford

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**Author:** ![mmcolli00](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/85e7bf/32.png) [@mmcolli00](https://www.ruby-forum.com/u/mmcolli00)\
**Post date:** [February 6, 2009, 4:01pm UTC](https://www.ruby-forum.com/t/question-looking-for-library-to-use-for-query-like-code/159634/2 "2009-02-06T16:01:00Z")

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Quoting Mmcolli00 Mom [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> ## auto, model truck, chevy, toyota, ford
> 
> Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/).

Of course this is possible, and rather easy to write. Here are bits I  
would use:

cars = hash.new

file = File.open(“textfile.txt”)  
file.each {  
| line |  
wordarray = line.split(/,\s\*/)

cars[wordarray[0]] \<\< wordarray[1]  
}  
file.close

file = File.open(“outfile.txt”, “w”)  
file \<\< "cars, "  
cars[“cars”].each { |car| file \<\< car \<\< ", " }  
file \<\< “\n”  
cars.[“truck”].each { |car| file \<\< car \<\< ", " }  
file \<\< “\n”  
file.close

This is not a complete, nor a general solution, but this should give you  
an  
idea.

Jean-Denis

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**Author:** ![mmcolli00](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/85e7bf/32.png) [@mmcolli00](https://www.ruby-forum.com/u/mmcolli00)\
**Post date:** [February 6, 2009, 4:08pm UTC](https://www.ruby-forum.com/t/question-looking-for-library-to-use-for-query-like-code/159634/3 "2009-02-06T16:08:39Z")

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On Feb 6, 2009, at 8:32 AM, Mmcolli00 Mom wrote:

> Can this be done with Ruby? (this may be a shot in the dark)

Anything can be done with Ruby. 😉

> Say you have a text file with a lot of data and you want to group  
> all of  
> your data by a specific value. Is there a way to code something in  
> ruby  
> similar to a query that you would create using sql. Can this even be  
> done using Ruby? And if so, is there a library that you can refer me  
> to?  
> If not, do you know any alternative ways? Thanks, MC

I’ll show some pure Ruby code below that seems to do what you want,  
but if you really want a query language you have several options.  
Personally, I would use the Amalgalite gem to get SQLite. You would  
then just read the data and write it into a database. You can then  
query it in anyway you like.

> how i’d like it to look:
> 
> car, honda, nissan,  
> truck, chevy, toyota, ford

Here’s some code that does that:

#!/usr/bin/env ruby -wKU

headers = DATA.gets.strip.split(/,\s\*/)

related = { }  
DATA.each do |row|  
fields = Hash[_headers.zip(row.strip.split(/,\s_/)).flatten]  
(related[fields[“auto”]] ||= []) \<\< fields[“model”]  
end

related.keys.sort.each do |key|  
puts(([key] + related[key]).join(", "))  
end

**END**  
auto, model  
car, honda  
truck, chevy  
car, nissan  
truck, toyota  
truck, ford

Hope it helps.

James Edward G. II

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**Author:** ![mmcolli00](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/85e7bf/32.png) [@mmcolli00](https://www.ruby-forum.com/u/mmcolli00)\
**Post date:** [February 6, 2009, 4:25pm UTC](https://www.ruby-forum.com/t/question-looking-for-library-to-use-for-query-like-code/159634/4 "2009-02-06T16:25:06Z")

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James’ solution to the previous question being so much better than mine  
(which I  
did for my learning purposes), I dare asking about how to iterate over  
two  
arrays in parallel. I don’t see a way to use the iteration methods, and  
my  
solution below doesn’t feel idiomatic at all:

array1 = [1, 2, 3]  
array2 = [“one”, “two”, “three”]

# note: both arrays are known to be the same size

(0…array1.size-1).each {  
| i |  
print “#{array2[i]} = #{array1[i]}\n”  
}

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**Author:** ![mmcolli00](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/85e7bf/32.png) [@mmcolli00](https://www.ruby-forum.com/u/mmcolli00)\
**Post date:** [February 6, 2009, 4:41pm UTC](https://www.ruby-forum.com/t/question-looking-for-library-to-use-for-query-like-code/159634/5 "2009-02-06T16:41:33Z")

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On Feb 6, 2009, at 9:24 AM, Jean-Denis M. wrote:

> James’ solution to the previous question being so much better than  
> mine (which I did for my learning purposes),

I think your solution was just fine.

> print “#{array2[i]} = #{array1[i]}\n”  
> }

Here’s one way:

> > array1 = (1…3).to\_a  
> > =\> [1, 2, 3]
> 
> > array2 = %w[one two three]  
> > =\> [“one”, “two”, “three”]
> 
> > array1.zip(array2) { |num, word| puts “#{num} #{word}” }  
> > 1 one  
> > 2 two  
> > 3 three  
> > =\> nil

and another:

> > require “generator”  
> > =\> true
> 
> > SyncEnumerator.new(array1, array2).each { |num, word| puts “#{num}  
> > #{word}” }  
> > 1 one  
> > 2 two  
> > 3 three  
> > =\> #\<SyncEnumerator:0x1115e58 @gens=[#\<Generator:0x1115de0  
> > @cont\_endp=#Continuation:0x11154bc, cont\_yieldnil, queue[],  
> > block#Proc:0x0111e15c@/usr/local/lib/ruby/1.8/generator.rb:71,  
> > cont\_next#\<Continuation:0x1115624, @index=3\>, #\<Generator:0x1115cc8  
> > @cont\_endp=#Continuation:0x111546c, cont\_yieldnil, queue[],  
> > block#Proc:0x0111e15c@/usr/local/lib/ruby/1.8/generator.rb:71,  
> > cont\_next#\<Continuation:0x1115570, @index=3\>]

Hope that helps.

James Edward G. II

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**Author:** ![mmcolli00](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/85e7bf/32.png) [@mmcolli00](https://www.ruby-forum.com/u/mmcolli00)\
**Post date:** [February 6, 2009, 4:32pm UTC](https://www.ruby-forum.com/t/question-looking-for-library-to-use-for-query-like-code/159634/6 "2009-02-06T16:32:10Z")

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On Fri, Feb 6, 2009 at 8:54 PM, Jean-Denis M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> James’ solution to the previous question being so much better than mine (which I  
> did for my learning purposes), I dare asking about how to iterate over two  
> arrays in parallel. I don’t see a way to use the iteration methods, and my  
> solution below doesn’t feel idiomatic at all:
> 
> array1 = [1, 2, 3]  
> array2 = [“one”, “two”, “three”]
> 
> # note: both arrays are known to be the same size

Use the block form of zip:

array1.zip(array2) {|i,j| print “#{i} = #{j}\n”}

martin

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**Author:** ![mmcolli00](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/85e7bf/32.png) [@mmcolli00](https://www.ruby-forum.com/u/mmcolli00)\
**Post date:** [February 6, 2009, 5:10pm UTC](https://www.ruby-forum.com/t/question-looking-for-library-to-use-for-query-like-code/159634/7 "2009-02-06T17:10:56Z")

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On Feb 6, 8:32 am, Mmcolli00 Mom [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> ## auto, model
> 
> Posted viahttp://www.ruby-forum.com/.

data = Hash.new {|h,k| h[k] = []}

IO.foreach(“myfile.txt”){|line|  
type, make = line.strip.split( / \*, \*/ )  
data[type] \<\< make  
}

p data

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<div class="post-metadata">

**Author:** ![mmcolli00](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/85e7bf/32.png) [@mmcolli00](https://www.ruby-forum.com/u/mmcolli00)\
**Post date:** [February 6, 2009, 5:46pm UTC](https://www.ruby-forum.com/t/question-looking-for-library-to-use-for-query-like-code/159634/8 "2009-02-06T17:46:08Z")

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> Hope that helps.

Yes indeed, quite a lot. Thanks to both of you.