Hi All,
I have following lines
m=['a','b','c']
puts m.each_with_index{|v,i| i}
which output in:
ruby try.rb
a
b
c
Exit code: 0
I was expecting to see indexes, rather than values.
Am I overlooking some trivial nuance or what.
Basically i wanted to print index values while iterating an array at
some other project.
and "each_with_index" seemed very obvious for the task but for the
unexpected result.
Raja
--
Posted via http://www.ruby-forum.com/\.
It is. But #each_with_index *returns* the Enumerable. You need to put
the put into the block:
irb(main):001:0> ['a','b','c'].each_with_index {|a,i| puts i}
0
1
2
=> ["a", "b", "c"]
irb(main):002:0>
Kind regards
robert
2007/7/19, Vin Raja <vineetraja@gmail.com>:
Hi All,
I have following lines
m=['a','b','c']
puts m.each_with_index{|v,i| i}which output in:
>ruby try.rb
a
b
c
>Exit code: 0I was expecting to see indexes, rather than values.
Am I overlooking some trivial nuance or what.
Basically i wanted to print index values while iterating an array at
some other project.
and "each_with_index" seemed very obvious for the task but for the
unexpected result.
irb(main):003:0> m.each_with_index{|v,i| i}
=> ["a", "b", "c"]
irb(main):004:0> m.each_with_index{|v,i| p i}
0
1
2
=> ["a", "b", "c"]
The i variable in the block is indeed the index. But the result of the entire
each_with_index expression is not the result of each block invocation, but the collection
of all the array elements.
marcel
On Thu, Jul 19, 2007 at 03:46:10PM +0900, Vin Raja wrote:
I have following lines
m=['a','b','c']
puts m.each_with_index{|v,i| i}which output in:
>ruby try.rb
a
b
c
>Exit code: 0
--
Marcel Molina Jr. <marcel@vernix.org>
Alle giovedì 19 luglio 2007, Vin Raja ha scritto:
Hi All,
I have following lines
m=['a','b','c']
puts m.each_with_index{|v,i| i}which output in:
>ruby try.rba
b
c>Exit code: 0
I was expecting to see indexes, rather than values.
Am I overlooking some trivial nuance or what.
Basically i wanted to print index values while iterating an array at
some other project.
and "each_with_index" seemed very obvious for the task but for the
unexpected result.Raja
You're telling ruby to print the return value of each with index, which,
according to the ri documentation, is the array itself. If you want to print
the different inidces, you need to put the call to puts inside the block:
m.each_with_index{|v,i| puts( i )}
Putting i as the last statement of the block simply makes that the return
value of the block, but this is ignored by each_with_index, so it's useless.
I hope this helps
Stefano
Thanks All,
I got the nuance.
But my problem just got a bit more messier.
have a look down here:
r = ['KLP','OGN' ]
msg =<<MSG
Found #{r.length} orders
#{r.map.each_with_index{|v,i| puts "(#{i+1}) #{v}\n" }}
MSG
puts msg
This prints:
ruby try.rb
(1) KLP
(2) OGN
Found 2 orders
KLPOGN
Exit code: 0
And this time I also know why, thanks again.
But what I actually wanted was this sort of output:
ruby try.rb
Found 2 orders
(1) KLP
(2) OGN
Exit code: 0
Any Help!
Thanks
raja
--
Posted via http://www.ruby-forum.com/\.
Actually Enumerable#each_with_index appears to return the receiver
object itself, identity is preserved.
irb(main):001:0> a = %w{a word array}
=> ["a", "word", "array"]
irb(main):002:0> a.equal?(a.each_with_index {|e, i| [e, i]})
=> true
irb(main):003:0> a = (1..3)
=> 1..3
irb(main):004:0> a.equal?(a.each_with_index {|e, i| [e, i]})
=> true
Although this is not documented, and could of course be overridden in
a class which includes enumerable or one of its subclasses.
On 7/19/07, Marcel Molina Jr. <marcel@vernix.org> wrote:
On Thu, Jul 19, 2007 at 03:46:10PM +0900, Vin Raja wrote:
> I have following lines
>
> m=['a','b','c']
> puts m.each_with_index{|v,i| i}
>
> which output in:
>
> >ruby try.rb
> a
> b
> c
> >Exit code: 0irb(main):003:0> m.each_with_index{|v,i| i}
=> ["a", "b", "c"]
irb(main):004:0> m.each_with_index{|v,i| p i}
0
1
2
=> ["a", "b", "c"]The i variable in the block is indeed the index. But the result of the entire
each_with_index expression is not the result of each block invocation, but the collection
of all the array elements.marcel
--
Marcel Molina Jr. <marcel@vernix.org>
--
Rick DeNatale
My blog on Ruby
http://talklikeaduck.denhaven2.com/
You are confusing string evaluation with output. You need to remove
the puts from the string interpolation or use a different approach.
I'd keep things simple and do
r = ['KLP','OGN' ]
print "found ", r.size, " orders\n"
r.each_with_index do |e,i|
print " (", i+1, ") ", e, "\n"
end
robert
2007/7/19, Vin Raja <vineetraja@gmail.com>:
Thanks All,
I got the nuance.
But my problem just got a bit more messier.
have a look down here:r = ['KLP','OGN' ]
msg =<<MSG
Found #{r.length} orders
#{r.map.each_with_index{|v,i| puts "(#{i+1}) #{v}\n" }}
MSGputs msg
This prints:
>ruby try.rb
(1) KLP
(2) OGN
Found 2 orders
KLPOGN>Exit code: 0
And this time I also know why, thanks again.
But what I actually wanted was this sort of output:
>ruby try.rb
Found 2 orders
(1) KLP
(2) OGN>Exit code: 0
Any Help!
[mailto:list-bounce@example.com] On Behalf Of Vin Raja:
# But what I actually wanted was this sort of output:
# >ruby try.rb
# Found 2 orders
# (1) KLP
# (2) OGN
just want you to show the evolution from your original scheme (spot the difference) to that of roberts (retaining your original inlining)
C:\family\ruby>cat -n try.rb
1 puts "---scheme 1---"
2 r = ['KLP','OGN']
3 msg =<<MSG
4 #{puts "Found #{r.length} orders"}
5 #{r.map.each_with_index{|v,i| puts "(#{i+1}) #{v}\n" }}
6 MSG
7 msg
8
9 puts "---scheme 2---"
10 r = ['KLP','OGN']
11 <<MSG
12 #{puts "Found #{r.length} orders"}
13 #{r.map.each_with_index{|v,i| puts "(#{i+1}) #{v}\n" }}
14 MSG
15
16 puts "---scheme 3---"
17 r = ['KLP','OGN']
18 puts "Found #{r.length} orders"
19 r.each_with_index{|v,i| puts "(#{i+1}) #{v}\n" }
C:\family\ruby>ruby try.rb
---scheme 1---
Found 2 orders
(1) KLP
(2) OGN
---scheme 2---
Found 2 orders
(1) KLP
(2) OGN
---scheme 3---
Found 2 orders
(1) KLP
(2) OGN
kind regards -botp
It looks like others have already clarified things for you. This is a
bit of a tangent, but I just wanted to mention that 'map' is
superfluous in the above code i.e. the output is identical with and
without it.
irb(main):001:0> r = ['KLP','OGN' ]
=> ["KLP", "OGN"]
irb(main):002:0> r
=> ["KLP", "OGN"]
irb(main):003:0> r.map
=> ["KLP", "OGN"]
On Jul 19, 3:12 am, Vin Raja <vineetr...@gmail.com> wrote:
r = ['KLP','OGN' ]
msg =<<MSG
Found #{r.length} orders
#{r.map.each_with_index{|v,i| puts "(#{i+1}) #{v}\n" }}
MSGputs msg
#... puts "(#{i+1}) #{v}\n" }
oops, lose "\n" pls.
One other variation which looks a little closer to what the OP wanted:
module Enumerable
def map_with_index
idx = -1
map{ |v| yield v,idx+=1 }
end
end
puts "---scheme 4---"
r = ['KLP','OGN']
msg =<<ENDMSG
Found #{r.length} orders
#{r.map_with_index{ |v,i| "(#{i+1}) #{v}"}.join("\n")}
ENDMSG
puts msg
On Jul 19, 3:06 am, Peña, Botp <b...@delmonte-phil.com> wrote:
1 puts "---scheme 1---"
2 r = ['KLP','OGN']
3 msg =<<MSG
4 #{puts "Found #{r.length} orders"}
5 #{r.map.each_with_index{|v,i| puts "(#{i+1}) #{v}\n" }}
6 MSG
7 msg
8
9 puts "---scheme 2---"
10 r = ['KLP','OGN']
11 <<MSG
12 #{puts "Found #{r.length} orders"}
13 #{r.map.each_with_index{|v,i| puts "(#{i+1}) #{v}\n" }}
14 MSG
15
16 puts "---scheme 3---"
17 r = ['KLP','OGN']
18 puts "Found #{r.length} orders"
19 r.each_with_index{|v,i| puts "(#{i+1}) #{v}\n" }
It doesn't hurt though - output is the same.
robert
2007/7/19, Peña, Botp <botp@delmonte-phil.com>:
#... puts "(#{i+1}) #{v}\n" }
oops, lose "\n" pls.
Phrogz wrote:
puts "---scheme 4---"
While I have found the thread fascinating, it appears to me
that the original code and the 4 schemes are simply trying
to avoid the definition of a function.
def msg(r)
puts "Found #{r.length} orders"
r.each_with_index{|v,i| puts "(#{i+1}) #{v}\n" }
end
x = ['KLP','OGN']
msg(x)
Can anyone explain what I am missing?
Thanks
Ian
--
Posted via http://www.ruby-forum.com/\.
# > #... puts "(#{i+1}) #{v}\n" }
# > oops, lose "\n" pls.
From: Robert Klemme [mailto:shortcutter@googlemail.com]
# 2007/7/19, Peña, Botp <botp@delmonte-phil.com>:
#
# It doesn't hurt though - output is the same.
' just little concern for the op. he might assume puts requires \n.
but you're right, it does not hurt. he'll learn it later anyway...
kind regards -botp
Thanks All
It cleared up a lot of mess up at my head.
thanks again