[lnkForumImage]
TotalShareware - Download Free Software
Confronta i prezzi di migliaia di prodotti.
Asp Forum
 Home | Login | Register | Search 


 

Forums >

comp.lang.ruby

DRY up consecutive gsub's - How to

RichardOnRails

4/10/2009 1:25:00 AM

Hi,

I have a csv file suitable for an Excel display. The file has column-
names on certain row.

In order to process subsequent rows I want to refer to their columns
symbolically using the column-names. That requires the column-names to
be cleaned up in order to create valid Ruby symbols.

The following worked fine:
if col_name
col_name.gsub!(/[\s]/, "")
col_name.gsub!(/[&]/, "And")
col_name.gsub!(/[#]/, "Number")
end

Each of the following one-liners failed:
col_name.gsub!(/[\s]/, ""). gsub!(/[&]/, "And").gsub!(/[#]/,
"Number") if col_name
col_name.gsub(/[\s]/, ""). gsub(/[&]/, "And").gsub(/[#]/, "Number")
if col_name

Can either of the one-liners be made to work?

The code is show in a larger (easier to read) context at http://www.pastie....

Thanks in Advance,
Richard




.
3 Answers

Phlip

4/10/2009 1:52:00 AM

0

RichardOnRails wrote:

> Each of the following one-liners failed:
> col_name.gsub!(/[\s]/, ""). gsub!(/[&]/, "And").gsub!(/[#]/,
> "Number") if col_name

col_name = col_name.to_s.gsub(/[\s]/, ""). gsub(/[&]/, "And").gsub(/[#]/,
"Number")

If you don't mind col_name shifting from a nil to a blank.

Also, the [] brackets add no value - both [\s] and \s are a one-width match.

Robert Dober

4/10/2009 1:58:00 AM

0

On Fri, Apr 10, 2009 at 3:30 AM, RichardOnRails
<RichardDummyMailbox58407@uscomputergurus.com> wrote:
> Hi,
>
> I have a csv file suitable for an Excel display. =A0The file has column-
> names on certain row.
>
> In order to process subsequent rows I want to refer to their columns
> symbolically using the column-names. That requires the column-names to
> be cleaned up in order to create valid Ruby symbols.
>
> The following worked fine:
> =A0 =A0 =A0 =A0if col_name
> =A0 =A0 =A0 =A0 =A0col_name.gsub!(/[\s]/, "")
> =A0 =A0 =A0 =A0 =A0col_name.gsub!(/[&]/, "And")
> =A0 =A0 =A0 =A0 =A0col_name.gsub!(/[#]/, "Number")
> =A0 =A0 =A0 =A0end
>
> Each of the following one-liners failed:
> =A0 =A0 =A0 =A0 col_name.gsub!(/[\s]/, ""). gsub!(/[&]/, "And").gsub!(/[#=
]/,
> "Number") if col_name
> =A0 =A0 =A0 =A0 col_name.gsub(/[\s]/, ""). gsub(/[&]/, "And").gsub(/[#]/,=
"Number")
> if col_name
>
> Can either of the one-liners be made to work?
>
> The code is show in a larger (easier to read) context at http://...
e.org/442456
>
> Thanks in Advance,
> Richard


Here is a oneliner
col.gsub!(/[\s&#]/){ |x| x =3D=3D "#" ? "Number" : x =3D=3D "&" ? "And" : "=
" }
just to show that your code is much better.
Why do you dislike it, it is readable and simple.
If you are worried about changes, you might potentially factor that out

[ /\s/, "", "&", "And", "#', "Number"].each_slice( 2 ) do | reg, rep |
col.gsub! reg, rep
end

HTH
Robert
>
>
>
> .
>
>
>



--=20
If you want to build a ship, don=92t herd people together to collect
wood and don=92t assign them tasks and work, but rather teach them to
long for the endless immensity of the sea.
-- Antoine de Saint-Exupery

RichardOnRails

4/10/2009 2:48:00 AM

0

On Apr 9, 9:25 pm, RichardOnRails
<RichardDummyMailbox58...@USComputerGurus.com> wrote:
> Hi,
>
> I have a csv file suitable for an Excel display.  The file has column-
> names on certain row.
>
> In order to process subsequent rows I want to refer to their columns
> symbolically using the column-names. That requires the column-names to
> be cleaned up in order to create valid Ruby symbols.
>
> The following worked fine:
>         if col_name
>           col_name.gsub!(/[\s]/, "")
>           col_name.gsub!(/[&]/, "And")
>           col_name.gsub!(/[#]/, "Number")
>         end
>
> Each of the following one-liners failed:
>          col_name.gsub!(/[\s]/, ""). gsub!(/[&]/, "And").gsub!(/[#]/,
> "Number") if col_name
>          col_name.gsub(/[\s]/, ""). gsub(/[&]/, "And").gsub(/[#]/, "Number")
> if col_name
>
> Can either of the one-liners be made to work?
>
> The code is show in a larger (easier to read) context athttp://www.pastie.....
>
> Thanks in Advance,
> Richard
>
> .

Hi Philip and Robert,

Thank you both for great responses.

First off, I still wanted to know what was the flaw in my one-liner;
I found two:
1. I needed carefully placed parenthesis
2. The parenthesized version failed because I just discovered) gsub!
returns nil when no change is made. Bad idea for my purpose; no doubt
Matz saw a good reason for it.

Bob, your version worked fine and fulfills my goal
Ditto for your version, Robert.
For both, I appended "if if col_name" to handle unnamed columns.

With two great choices, my aesthetics lead me to Robert's version
because:
1. I like the x.gsub! ... better than x = x.gsub ...
2. The single gsub! with the choices laid out in order packs expanding
it for additional cases with the least typing.

Again, thank you both very much for your help.

Best wishes,
Richard

Most of all, I like one-liners much better than 5-liners for
readability.