This is quite embarassing because I Don't consider myself a poor
programmer, but I just started looking at ruby the other day.
Blocks seem to be a good way to iterate through something to search for
an entry for instance. It's easy to return the object that meets
certain criteria using blocks but I'm finding it hard to return the
index of that particular object in, say, an array.
as an example
arr=[4,1,3,7]
arr.find { |f| f==someval }
will return the val within arr that matches someval, which doesn't
really help me because I already have someval
How do I actually return the index in arr to the first match of someval.
so if someval == 3, my block would return 2, for the above example
On 15/03/06, Tod McIntyre <todmcintyre@gmail.com> wrote:
This is quite embarassing because I Don't consider myself a poor
programmer, but I just started looking at ruby the other day.
Blocks seem to be a good way to iterate through something to search for
an entry for instance. It's easy to return the object that meets
certain criteria using blocks but I'm finding it hard to return the
index of that particular object in, say, an array.
as an example
arr=[4,1,3,7]
arr.find { |f| f==someval }
will return the val within arr that matches someval, which doesn't
really help me because I already have someval
How do I actually return the index in arr to the first match of someval.
so if someval == 3, my block would return 2, for the above example
--
Daniel Baird http://danielbaird.com (TiddlyW;nks! :: Whiteboard Koala :: Blog :: Things
That Suck)
[[My webhost uptime is ~ 92%.. if no answer pls call again later!]]
(The upshot is that in CVS, 1.9 now allows a block to #index to specify
what is to be found).
In the meantime, the current #index should do the job for most cases
(e.g. the example you showed):
a = [:a,:b,:c,:d,:e]
# => [:a, :b, :c, :d, :e]
a.index(:a)
# => 0
a.index(:e)
# => 4
···
On Wed, 2006-03-15 at 13:08 +0900, Tod McIntyre wrote:
This is quite embarassing because I Don't consider myself a poor
programmer, but I just started looking at ruby the other day.
Blocks seem to be a good way to iterate through something to search for
an entry for instance. It's easy to return the object that meets
certain criteria using blocks but I'm finding it hard to return the
index of that particular object in, say, an array.
"Tod McIntyre" <todmcintyre@gmail.com> wrote in message news:da9c35364b80a5c4e9e603e0db41190a@ruby-forum.com...
This is quite embarassing because I Don't consider myself a poor
programmer, but I just started looking at ruby the other day.
Blocks seem to be a good way to iterate through something to search for
an entry for instance. It's easy to return the object that meets
certain criteria using blocks but I'm finding it hard to return the
index of that particular object in, say, an array.
as an example
arr=[4,1,3,7]
arr.find { |f| f==someval }
will return the val within arr that matches someval, which doesn't
really help me because I already have someval
Yeah, but this is just a special case. With a block you can employ arbitrary selection criteria - not just ==.
How do I actually return the index in arr to the first match of someval.
so if someval == 3, my block would return 2, for the above example
As Ross and Daniel have pointed out already, use #index.
"Tod McIntyre" <todmcintyre@gmail.com> wrote in message
news:da9c35364b80a5c4e9e603e0db41190a@ruby-forum.com...
arr=[4,1,3,7]
arr.find { |f| f==someval }
will return the val within arr that matches someval, which doesn't
really help me because I already have someval
Yeah, but this is just a special case. With a block you can employ
arbitrary selection criteria - not just ==.
How do I actually return the index in arr to the first match of someval.
so if someval == 3, my block would return 2, for the above example
As Ross and Daniel have pointed out already, use #index.
Kind regards
robert
Once again I knew this would be a simple answer!! I thank you for your
quick responses. Obviously I should be reading the api more thoroughly
before posting.
"Tod McIntyre" <todmcintyre@gmail.com> wrote in message news:859233703646963b97fe343fb84b6e0f@ruby-forum.com...
Robert Klemme wrote:
"Tod McIntyre" <todmcintyre@gmail.com> wrote in message
news:da9c35364b80a5c4e9e603e0db41190a@ruby-forum.com...
arr=[4,1,3,7]
arr.find { |f| f==someval }
will return the val within arr that matches someval, which doesn't
really help me because I already have someval
Yeah, but this is just a special case. With a block you can employ
arbitrary selection criteria - not just ==.
How do I actually return the index in arr to the first match of someval.
so if someval == 3, my block would return 2, for the above example
As Ross and Daniel have pointed out already, use #index.
Kind regards
robert
Once again I knew this would be a simple answer!! I thank you for your
quick responses. Obviously I should be reading the api more thoroughly
before posting.
Ah, don't bother. The API of the standard lib has it's humps and bumps (for example not fully consistent usage of ! for destructive methods etc.) so it's normal to fall into one or the other pit initially.
Ah, don't bother. The API of the standard lib has it's humps and bumps (for example not fully consistent usage of ! for destructive methods etc.) so it's normal to fall into one or the other pit initially.
I have to leap to the defense of ! It really is consistent:
* given meth and meth!, meth! is the more "dangerous" version
* "dangerous" often means "receiver-changing", but definitely
does not have to mean that
* methods whose names already imply receiver-changing don't
have a ! because they don't need one, and also ! methods
only come in pairs with a non-! equivalent. (It would be
hard to imagine what "Replace the contents of this string
object, but without changing the object" would mean....)
"Implying receiver-changing" is of course in the eyes of Matz But
while there are judgements, I don't think there's any inconsistency.
<dblack@wobblini.net> wrote in message news:Pine.LNX.4.64.0603150822080.17960@wobblini.net...
Hi --
Ah, don't bother. The API of the standard lib has it's humps and bumps (for example not fully consistent usage of ! for destructive methods etc.) so it's normal to fall into one or the other pit initially.
I have to leap to the defense of ! It really is consistent:
* given meth and meth!, meth! is the more "dangerous" version
* "dangerous" often means "receiver-changing", but definitely
does not have to mean that
Although it's certainly the most common use of "!".
* methods whose names already imply receiver-changing don't
have a ! because they don't need one, and also ! methods
only come in pairs with a non-! equivalent. (It would be
hard to imagine what "Replace the contents of this string
object, but without changing the object" would mean....)
"Implying receiver-changing" is of course in the eyes of Matz But
while there are judgements, I don't think there's any inconsistency.
Um, yes. I should print this out and place it in front of my monitor. Somehow I keep forgetting this definition - must be some old newsgroup thread having anchored deep in my subconscious.
It really is consistent: