Forum: Ruby Array methods creating confusions as per their functionalities

Can any one just elaborate how the below works in Ruby, by definition
they are not quite clear. Hope a small code snippet may help to
understand them at their core,how they works?

array.zip(arg, ...)

array.transpose

array.rassoc(key)

array.pack(aTemplateString)

array.frozen?

array.flatten

array.hash


Thanks in advance!

Hello,

I don't want to be rude or anything, but haven't you read the
documentation over at http://www.ruby-doc.org/core-1.9.3/Array.html ?
All the methods you asked us to explain are documented there. If I
remember correctly, you also asked for the difference for map and map!
not too long ago. The solution also was written in the documentation, as
was pointed out.

In general, I always found a google search with "Ruby [classname]"
giving me all the info I wanted. It's also much quicker than asking in
the list. ;)

Kind regards,
Calvin

Try reading http://apidock.com/ruby/Array/zip etc.

Calvin B. wrote in post #1092020:
> Hello,
>

I agree with your point, as I am a newbie so not that much confident on 
the methods how are they defined in the docs.I tried to understand a bit 
by test code,nothing in my HEAD! :( here is a small code for Pack() 
method of Array class instance.

irb(main):001:0> n = [ 65, 66, 67 ]
=> [65, 66, 67]
irb(main):002:0> n.pack("CCC")
=> "ABC"
irb(main):003:0> n.pack("ccc")
=> "ABC"
irb(main):004:0> n.pack("sss")
=> "A\x00B\x00C\x00"
irb(main):005:0> n.pack("SSS")
=> "A\x00B\x00C\x00"
irb(main):006:0> n.pack("qqq")
=> 
"A\x00\x00\x00\x00\x00\x00\x00B\x00\x00\x00\x00\x00\x00\x00C\x00\x00\x00\x00\
x00\x00\x00"
irb(main):007:0> n.pack("QQQ")
=> 
"A\x00\x00\x00\x00\x00\x00\x00B\x00\x00\x00\x00\x00\x00\x00C\x00\x00\x00\x00\
x00\x00\x00"
irb(main):008:0>

Now here you can see that I used directives as `c` and `C`;`q` and `Q` . 
But looking at the console output i didn't get any differences. But I 
know there should be,so need your help to pin point me,as you are 
experienced! I always obey your guide,directions n all.

Alex van der Ruchei wrote in post #1092021:
> Try reading http://apidock.com/ruby/Array/zip etc.

Wow nice docs you have provided! its too handy to understand as it 
explains everything with small codes.

let me look into the docs you just provided.

Thanks for your time!

Arup Rakshit wrote in post #1092023:
> Alex van der Ruchei wrote in post #1092021:
>> Try reading http://apidock.com/ruby/Array/zip etc.
>
> Wow nice docs you have provided! its too handy to understand as it
> explains everything with small codes.
>
> let me look into the docs you just provided.
>
> Thanks for your time!

to understand the ZIP method i used the below code,but getting an 
error.I might overlooked the bad area.can you help?

irb(main):008:0> a = [ 4, 5, 6 ]
=> [4, 5, 6]
irb(main):009:0> b = [ 7, 8, 9 ]
=> [7, 8, 9]
irb(main):010:0> [1,2].zip(a,b)
=> [[1, 4, 7], [2, 5, 8]]
irb(main):011:0> a.zip([1,2,]){|i|i>4}
NoMethodError: undefined method `>' for [4, 1]:Array
        from (irb):11:in `block in irb_binding'
        from (irb):11:in `zip'
        from (irb):11
        from C:/Ruby193/bin/irb:12:in `<main>'
irb(main):012:0> a.zip([1,2,]){|i|i>4}
NoMethodError: undefined method `>' for [4, 1]:Array
        from (irb):12:in `block in irb_binding'
        from (irb):12:in `zip'
        from (irb):12
        from C:/Ruby193/bin/irb:12:in `<main>'
irb(main):013:0> a.zip([1,2,]){|i|(i>4)}
NoMethodError: undefined method `>' for [4, 1]:Array
        from (irb):13:in `block in irb_binding'
        from (irb):13:in `zip'
        from (irb):13
        from C:/Ruby193/bin/irb:12:in `<main>'
irb(main):014:0> a.zip([1,2,]){|i|i>4}
NoMethodError: undefined method `>' for [4, 1]:Array
        from (irb):14:in `block in irb_binding'
        from (irb):14:in `zip'
        from (irb):14
        from C:/Ruby193/bin/irb:12:in `<main>'
irb(main):015:0>

Thanks!

Arup Rakshit wrote in post #1092018:
> Can any one just elaborate how the below works in Ruby, by definition
> they are not quite clear. Hope a small code snippet may help to
> understand them at their core,how they works?
>

> array.frozen?

My confusion or knowledge gap here is what the `frozen` means in Ruby 
platform with the array? How an array can be `frozen`. The document said 
only what the functions does in reality. which is "Return true if this 
array is frozen (or temporarily frozen while being sorted)." . But this 
is for me not enough to understand why Ruby brought the "frozen" 
concept. How and what scenarios made an array as frozen array in ruby? 
here is the pain. I hope that anyone of this forum will help me out to 
clear the logic within me.


Thanks!

You can "freeze" most mutable objects (by calling #freeze) to make them 
immutable.

You can still e.g. access elements of a frozen array, but trying to 
add/remove/modify them will cause an exception.

Bartosz Dziewoński wrote in post #1092029:
> You can "freeze" most mutable objects (by calling #freeze) to make them
> immutable.
>
> You can still e.g. access elements of a frozen array, but trying to
> add/remove/modify them will cause an exception.

any small code, on your sentences,if you give,it would be better for 
understand with scenarios!

On Saturday 12 January 2013 Arup Rakshit wrote
> only what the functions does in reality. which is "Return true if this
> Posted via http://www.ruby-forum.com/.
A frozen object is an object which can't be modified. You freeze an 
object
using its freeze method. To see an example, run the following code:

a=[1,2,3]
a.delete_at 1
p a
b=[1,2,3]
b.freeze
b.delete_at 1

You'll see that, while a.delete_at 1 changes the array, b.delete_at 1 
raises
an exception, because b had been frozen and therefore it can't be 
modified.

According to the questions you're posting, it seems to me you haven't 
read a
comprehensive ruby book. Have you tried the online version of 
Programming Ruby
(http://docs.ruby-doc.com/docs/ProgrammingRuby/)? It free and, even if 
written
for an old version of ruby, most of it is still accurate.

I hope this helps

Stefano