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comp.lang.ruby

Dynamically create an unknown number of arrays

Shandy Nantz

2/6/2009 4:22:00 PM

I need to create an unknow number of arrays on the fly (could be 1 array
could be 10, I don't know), is there a way to do this in Ruby and also
name them dynamically? I also need to set those array's to a collection
of stuff found in a table. My Ruby is pretty rusty, and I am not sure if
I can simply set an array to a group of stuff. If I have rows in a table
that can be accessed by saying @user.table_name, can I say:

a = Array.new
a = @user.table_name

Thanks for any help,

-S
--
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4 Answers

Robert Klemme

2/6/2009 5:02:00 PM

0

On 06.02.2009 17:21, Shandy Nantz wrote:
> I need to create an unknow number of arrays on the fly (could be 1 array
> could be 10, I don't know), is there a way to do this in Ruby and also
> name them dynamically? I also need to set those array's to a collection
> of stuff found in a table. My Ruby is pretty rusty, and I am not sure if
> I can simply set an array to a group of stuff. If I have rows in a table
> that can be accessed by saying @user.table_name, can I say:
>
> a = Array.new
> a = @user.table_name

You can say, or rather: write, that - but the effect would be
disappointing. The second assignment simply overwrites the first one
rendering it completely superfluous.

You can do this

arrays = Array.new(how_many) {[]}

Cheers

robert

7stud --

2/6/2009 5:21:00 PM

0

Shandy Nantz wrote:
> I need to create an unknow number of arrays on the fly (could be 1 array
> could be 10, I don't know), is there a way to do this in Ruby and also
> name them dynamically? I also need to set those array's to a collection
> of stuff found in a table. My Ruby is pretty rusty, and I am not sure if
> I can simply set an array to a group of stuff. If I have rows in a table
> that can be accessed by saying @user.table_name, can I say:
>
> a = Array.new
> a = @user.table_name
>
> Thanks for any help,
>
> -S

--data.txt--
apple, banana, strawberry
10, 20, 30, 40
red blue green yellow black
100 200 300
a b c d
-----------

data = []
num_arrays = rand(5)

File.open("data.txt") do |f|
num_arrays.times do
line = f.gets.strip()
data << line.split("/,?\s*/")
end
end

p data

--output:--
[["apple, banana, strawberry"], ["10, 20, 30, 40"], ["red blue green
yellow black"]]

The names of the arrays are: data[0], data[1], data[2]

--
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Shandy Nantz

2/6/2009 5:26:00 PM

0

>
> You can say, or rather: write, that - but the effect would be
> disappointing. The second assignment simply overwrites the first one
> rendering it completely superfluous.
>
> You can do this
>
> arrays = Array.new(how_many) {[]}
>
> Cheers
>
> robert
I have done some digging around and this is what I have written down on
paper - not tested yet at all:

@array_count = @user.tabledef.count #returns a 3, for example
@count = 0

until @count == @array_count - 1 do
eval("#{@count} = @user.tabledefs["#{count}.items)
@count += 1
end

What I was hoping is that this would return 3 distintive arrays, is this
not correct? What I am trying to do is build a table with x many columns
and y many rows but before hand I know neither what x or y is going to
be.

Also, assuming the above codes works (and assuming that there is not an
easier way to do this, which I'm thinking there is) how do I access the
arrays? Are they stored in a hash? or a variable? Thanks,

-S
--
Posted via http://www.ruby-....

7stud --

2/6/2009 5:34:00 PM

0

7stud -- wrote:
> Shandy Nantz wrote:
>> I need to create an unknow number of arrays on the fly (could be 1 array
>> could be 10, I don't know), is there a way to do this in Ruby and also
>> name them dynamically? I also need to set those array's to a collection
>> of stuff found in a table. My Ruby is pretty rusty, and I am not sure if
>> I can simply set an array to a group of stuff. If I have rows in a table
>> that can be accessed by saying @user.table_name, can I say:
>>
>> a = Array.new
>> a = @user.table_name
>>
>> Thanks for any help,
>>
>> -S
>
> --data.txt--
> apple, banana, strawberry
> 10, 20, 30, 40
> red blue green yellow black
> 100 200 300
> a b c d
> -----------
>
> data = []
> num_arrays = rand(5)
>
> File.open("data.txt") do |f|
> num_arrays.times do
> line = f.gets.strip()
> data << line.split("/,?\s*/")
> end
> end
>
> p data
>
> --output:--
> [["apple, banana, strawberry"], ["10, 20, 30, 40"], ["red blue green
> yellow black"]]
>
> The names of the arrays are: data[0], data[1], data[2]

Whoops. No quotes around regex's in ruby, and that regex doesn't work
anyway.

If you have comma delimited data like this:

--data.txt-----------
apple, banana, strawberry
10, 20, 30, 40
red, blue, green, yellow, black
100, 200, 300
a, b, c, d
---------------------

you can use this for the regex:

pieces = line.split(/,\s*/)

If your data is space delimited, you can use:

pieces = line.split(/\s+/)


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