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How can I generate new variables?

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  How can I generate new variables? "Kyle X." <haebooty@yahoo.com> - 2011-03-30 19:42 -0500
    Re: How can I generate new variables? 7stud -- <bbxx789_05ss@yahoo.com> - 2011-03-30 20:14 -0500
      Re: How can I generate new variables? "Kyle X." <haebooty@yahoo.com> - 2011-03-30 22:08 -0500
        Re: How can I generate new variables? Gunther Diemant <g.diemant@gmx.net> - 2011-03-31 03:08 -0500
          Re: How can I generate new variables? "Kyle X." <haebooty@yahoo.com> - 2011-03-31 14:30 -0500
        Re: How can I generate new variables? Robert Klemme <shortcutter@googlemail.com> - 2011-03-31 03:11 -0500
        Re: How can I generate new variables? 7stud -- <bbxx789_05ss@yahoo.com> - 2011-03-31 20:06 -0500
    Re: How can I generate new variables? "Kyle X." <haebooty@yahoo.com> - 2011-04-02 01:18 -0500
      Re: How can I generate new variables? Robert Klemme <shortcutter@googlemail.com> - 2011-04-04 02:15 -0500

#1997 — How can I generate new variables?

Hello, this is not so much a sketchup question as a Ruby one that I
cannot figure out. What I am trying to do is create new variables that
all have the same base name then add a number to make a series of
variables named like wall1, wall2, wall3, ect.

What I am trying to do is take an array, lets call it originalarray,
which has say 64 objects in it, and create 8 smaller arrays from this.
So array1 would be orginalarray[0-7], array2 would be
originalarray[8-15], and so on for 8 new arrays. The problem is I do not
know the length of the original array, as it is being populated by data
from an xml sheet, but I know the multiple of how it is being created,
ie by multiples of 8.

I have been trying to do this using loops doing something like:

    n=0
    while n != originalarray.length/8
      n=n.to_s
      array+n=originalarray[0..7]
      n=n.to_i
      n=n+1
    end



I realize that is doesn't work at all in that you cannot make variables
like this, I am just trying to give a better picture of what my goal is.
So I am wondering is it possible to accomplish this at all, and if so
how? Or is there a much easier way to do this using classes or some
other method to accomplish the same goal?

Any help would be greatly appreciated. Thank you in advance for your
time.

-- 
Posted via http://www.ruby-forum.com/.

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#2001

Kyle X. wrote in post #990090:
> Hello, this is not so much a sketchup question as a Ruby one that I
> cannot figure out. What I am trying to do is create new variables that
> all have the same base name then add a number to make a series of
> variables named like wall1, wall2, wall3, ect.
>

That is a typical beginner question.  You NEVER need to do that.  All 
computer languages have arrays for that purpose.


> What I am trying to do is take an array, lets call it originalarray,
> which has say 64 objects in it, and create 8 smaller arrays from this.
> So array1 would be orginalarray[0-7], array2 would be
> originalarray[8-15], and so on for 8 new arrays. The problem is I do not
> know the length of the original array, as it is being populated by data
> from an xml sheet, but I know the multiple of how it is being created,
> ie by multiples of 8.
>
> I have been trying to do this using loops doing something like:
>
>     n=0
>     while n != originalarray.length/8
>       n=n.to_s
>       array+n=originalarray[0..7]
>       n=n.to_i
>       n=n+1
>     end
>
>
>
> I realize that is doesn't work at all in that you cannot make variables
> like this, I am just trying to give a better picture of what my goal is.
> So I am wondering is it possible to accomplish this at all, and if so
> how?

Using arrays.  An array can contain anything--including other arrays:


require 'enumerator'  #not necessary in ruby 1.9

master_arr = []
data = [1, 2, 3,  4, 5, 6,  7, 8]

data.each_slice(3) do |sub_arr|
  master_arr << sub_arr
end

p master_arr

--output:--
[[1, 2, 3], [4, 5, 6], [7, 8]]

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#2019

First off thank you for the reply, and as you can probably tell I am 
very novice at ruby ><. However I am running into a few issues with 
this.

> Using arrays.  An array can contain anything--including other arrays:
>
>
> require 'enumerator'  #not necessary in ruby 1.9
>
> master_arr = []
> data = [1, 2, 3,  4, 5, 6,  7, 8]
>
> data.each_slice(3) do |triplet|
>   master_arr << triplet
> end
>
> p master_arr
>
> --output:--
> [[1, 2, 3], [4, 5, 6], [7, 8]]

I am writing this for SketchUP so I am using Ruby 1.8.6 and am having an 
issue with require 'enumerator', as it does not exist in their library 
as far as I can tell --- in turn the "each_slice" command does not 
function.

I was wondering if you could help me understand this command better as 
well.  "data.each_slice(3) do |triplet|"  The "(3)" here means slice 
after 3 entries in data correct?  The word triplet used, is this word 
required or could it be any word as long as it is consistent below i.e. 
:  do |x| master_arr << x?  Sorry for the basic question, but I just 
want to clarify.

>
> The names of the arrays are:
>
>    master_arr[0]
>    master_arr[1]
>    master_arr[2]
>
> Voila!  But in ruby, you rarely need to refer to index positions in an
> array because you can do this:
>
> master_arr.each do |arr|
>   p arr
> end
>
> --output:--
> [1, 2, 3]
> [4, 5, 6]
> [7, 8]
>
> Or this:
>
> master_arr.each do |arr|
>   new_arr = arr.map do |element|
>     element * 2
>   end
>
>   p new_arr
> end
>
> --output:--
> [2, 4, 6]
> [8, 10, 12]
> [14, 16]

The rest I think I have figured out, but still not 100% on the map 
function.

Thank you again for your time.

-- 
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#2028

[Note:  parts of this message were removed to make it a legal post.]

2011/3/31 Kyle X. <haebooty@yahoo.com>

>
> I am writing this for SketchUP so I am using Ruby 1.8.6 and am having an
> issue with require 'enumerator', as it does not exist in their library
> as far as I can tell --- in turn the "each_slice" command does not
> function.
>
> Then you must write your own version. For example
def slice(array, chunk_size)
  result = []
  array.each_with_index do |element, index|
    result << [] if index % chunk_size == 0
    result.last << element
  end

  result
end

arr = [1,2,3,4,5,6]
slice(arr,2)   #=> [[1,2],[3,4],[5,6]]

I was wondering if you could help me understand this command better as
> well.  "data.each_slice(3) do |triplet|"  The "(3)" here means slice
> after 3 entries in data correct?  The word triplet used, is this word
> required or could it be any word as long as it is consistent below i.e.
> :  do |x| master_arr << x?  Sorry for the basic question, but I just
> want to clarify.
>
> Your right. You can call the thing triplet, x or chunky_bacon. Its just a
name for a local variable.

--
gd

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#2063

Thank you all very much for your responses.  Both solutions work great. 
Thanks again.

-- 
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#2029

On Thu, Mar 31, 2011 at 5:08 AM, Kyle X. <haebooty@yahoo.com> wrote:
> First off thank you for the reply, and as you can probably tell I am
> very novice at ruby ><. However I am running into a few issues with
> this.
>
>> Using arrays.  An array can contain anything--including other arrays:
>>
>>
>> require 'enumerator'  #not necessary in ruby 1.9
>>
>> master_arr = []
>> data = [1, 2, 3,  4, 5, 6,  7, 8]
>>
>> data.each_slice(3) do |triplet|
>>   master_arr << triplet
>> end
>>
>> p master_arr
>>
>> --output:--
>> [[1, 2, 3], [4, 5, 6], [7, 8]]
>
> I am writing this for SketchUP so I am using Ruby 1.8.6 and am having an
> issue with require 'enumerator', as it does not exist in their library
> as far as I can tell --- in turn the "each_slice" command does not
> function.

You can easily cook it yourself

module Enumerable
  def each_slice(n)
    a = []

    each do |x|
      a << x

      if a.size == n
        yield a
        a.clear
      end
    end

    yield a unless a.empty?
    self
  end
end

> I was wondering if you could help me understand this command better as
> well.  "data.each_slice(3) do |triplet|"  The "(3)" here means slice
> after 3 entries in data correct?

Correct.

>  The word triplet used, is this word
> required or could it be any word as long as it is consistent below i.e.
> :  do |x| master_arr << x?  Sorry for the basic question, but I just
> want to clarify.

Yes, it's the name of the block argument.  You can name it anyway you
like.  You should only avoid reusing a name used outside the block in
order to avoid confusion and incompatibility should the program be
executed on 1.9 at one day.

You can even use three names!

irb(main):041:0> Array.new(10) {|idx| idx}
=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
irb(main):042:0> Array.new(10) {|idx| idx}.each_slice(3)
{|first,second,third| p first}
0
3
6
9
=> nil

> The rest I think I have figured out, but still not 100% on the map
> function.

Enumerable#map sends all values through a conversion function and
collects them in a new Array:

irb(main):043:0> Array.new(10) {|idx| idx}.map {|x| x + 100}
=> [100, 101, 102, 103, 104, 105, 106, 107, 108, 109]

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

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#2076

Kyle X. wrote in post #990113:
> First off thank you for the reply, and as you can probably tell I am
> very novice at ruby >

No problem--that's what this forum is for.

>>
>> require 'enumerator'  #not necessary in ruby 1.9
>>
>> master_arr = []
>> data = [1, 2, 3,  4, 5, 6,  7, 8]
>>
>> data.each_slice(3) do |triplet|
>>   master_arr << triplet
>> end
>>
>> p master_arr
>>
>> --output:--
>> [[1, 2, 3], [4, 5, 6], [7, 8]]
>
> I am writing this for SketchUP so I am using Ruby 1.8.6 and am having an
> issue with require 'enumerator', as it does not exist in their library
> as far as I can tell
>

I'm using ruby 1.8.6 too, and the Enumerator module is part of the ruby 
standard library.  Are you sure you spelled it right?  But if it's not 
provided, it's not provided.


> I was wondering if you could help me understand this command better as
> well.  "data.each_slice(3) do |triplet|"  The "(3)" here means slice
> after 3 entries in data correct?

Yes, the each_slice() method allows you to chop up an array into chunks 
of the specified size.

> The word triplet used, is this word
> required or could it be any word as long as it is consistent below i.e.
> :  do |x| master_arr << x?  Sorry for the basic question, but I just
> want to clarify.
>

'triplet' is just a descriptive variable name.  It is a "block 
parameter" which is just like a method parameter:

def do_stuff(x)  #x is a method parameter
  x+2  #or you can explicitly write: return x+2
end

answer = do_stuff(5)
puts answer   #=> 7


Ruby uses blocks everywhere.  Here is a simple example:

words = ["hello", "world", "goodbye"]

words.each do |word|
  puts word
end

--output:--
hello
world
goodbye

The each() method sends each element of the array to the block, which is 
this part:

      do |word|
  puts word
end

'do' signals the start of a block.  What happens is that ruby calls the 
block,  which is like a method with, for each element of the array.  In 
my example, the element of the array is assigned to the variable named 
'word', and then inside the block you can do whatever you want to the 
word variable.

The map() function, like each(), tells ruby to send each element of the 
array to the block.  However, map() also *takes the return value of the 
block* and shoves it into a new array:


words = ["hello", "world", "goodbye"]

new_arr = words.map do |x|
  1
end

p new_arr

--output:--
[1, 1, 1]

In that example, the block returns 1 for every element of the array. 
But you can use map to do more useful things--like capitalize all the 
words in the array:

words = ["hello", "world", "goodbye"]

new_arr = words.map do |x|
  x.capitalize  #same as: 'return x.capitalize'
end

p new_arr

--output:--
["Hello", "World", "Goodbye"]

So whenever, you want to do something to every member of an array, map() 
is a good choice.

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#2146

Dear 7stud,

Thank you for the very clear descriptions.  Your examples are much more 
helpful than the examples I find in places like -
http://www.germane-software.com/software/rexml/doc/index.html

-- 
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#2239

On Sat, Apr 2, 2011 at 8:18 AM, Kyle X. <haebooty@yahoo.com> wrote:
> Dear 7stud,
>
> Thank you for the very clear descriptions.  Your examples are much more
> helpful than the examples I find in places like -
> http://www.germane-software.com/software/rexml/doc/index.html

But that is about REXML and not general iteration of collections in
Ruby.  For REXML: did you look at the tutorial?
http://www.germane-software.com/software/rexml/docs/tutorial.html

Cheers

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

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