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comp.lang.ruby

sort array by some text

frytaz@gmail.com

3/12/2008 5:03:00 AM

Hi, i have array with file names
a = ['one.jpg', 'two.txt', 'three.pdf']
how can i sort it that always first value will be *.txt file ?

Thanks, fryt
--
Posted via http://www.ruby-....
17 Answers

Todd Benson

3/12/2008 5:26:00 AM

0

On Wed, Mar 12, 2008 at 12:02 AM, Ma Fe <frytaz@gmail.com> wrote:
> Hi, i have array with file names
> a = ['one.jpg', 'two.txt', 'three.pdf']
> how can i sort it that always first value will be *.txt file ?
>
> Thanks, fryt
> --
> Posted via http://www.ruby-....
>
>

a = ['one.jpg', 'two.txt', 'three.pdf']
#assume you want reverse sort?
a.sort_by {|i| i.scan /\..*?$/}.reverse

You understand, of course, this won't give you .txt as a first hit if
you have a .zip. It simply reverse sorts by the letters following a
dot.

If you just want .txt files, maybe use #select instead...

a.select {|i| i =~ /\..txt$/}

Or you could use #partition if you don't care about the order of other
attributes, but want to hold on to the entire array...

a.partition {|i| i =~ /\..txt$/}.flatten

Todd

frytaz@gmail.com

3/12/2008 5:35:00 AM

0

well I dont know where in array i have .txt files but its sure that
there is just one and i want to put it at first place of array...
--
Posted via http://www.ruby-....

Todd Benson

3/12/2008 5:53:00 AM

0

On Wed, Mar 12, 2008 at 12:34 AM, Ma Fe <frytaz@gmail.com> wrote:
> well I dont know where in array i have .txt files but its sure that
> there is just one and i want to put it at first place of array...
> --
>

Try using the #partition method (my last example) then. It gives you
all .txt files at the beginning of the array. I made a mistake
though. There should only be one dot, not two for that (same thing if
you use #select)...

a = ['one.jpg', 'two.txt', 'three.pdf', 'four.txt']
a_new = a.partition {|i| i =~ /\.txt$/}
p a_new

Todd

Robert Klemme

3/12/2008 10:34:00 AM

0

2008/3/12, Todd Benson <caduceass@gmail.com>:
> On Wed, Mar 12, 2008 at 12:34 AM, Ma Fe <frytaz@gmail.com> wrote:
> > well I dont know where in array i have .txt files but its sure that
> > there is just one and i want to put it at first place of array...
>
> Try using the #partition method (my last example) then. It gives you
> all .txt files at the beginning of the array. I made a mistake
> though. There should only be one dot, not two for that (same thing if
> you use #select)...
>
> a = ['one.jpg', 'two.txt', 'three.pdf', 'four.txt']
> a_new = a.partition {|i| i =~ /\.txt$/}
> p a_new

For the fun of it: here's a solution with #inject:

irb(main):009:0> a = ['one.jpg', 'two.txt', 'three.pdf']
=> ["one.jpg", "two.txt", "three.pdf"]
irb(main):010:0> a.inject([[],[]]) {|(tx,ot),x| (/\.txt$/ =~ x ? tx :
ot) << x;[tx,ot]}.flatten
=> ["two.txt", "one.jpg", "three.pdf"]

There's even a version with *two* #injects:

irb(main):011:0> a.inject([[],[]]) {|(tx,ot),x| (/\.txt$/ =~ x ? tx :
ot) << x;[tx,ot]}.inject {|a,b| a.concat b}
=> ["two.txt", "one.jpg", "three.pdf"]

It's been a while so I *had* to do it. Once in a while I need my
#injection. :-))

Kind regards

robert

--
use.inject do |as, often| as.you_can - without end

Rodrigo Bermejo

3/12/2008 2:44:00 PM

0


a = ['one.jpg', 'two.txt', 'three.pdf','a.txt', 'a.az' , 'a.z']
a_new=a.sort_by do |x|
if x =~ /\.txt$/
0
else
1
end
end
p a_new
--> ["a.txt", "two.txt", "one.jpg", "three.pdf", "a.az", "a.z"]

the sort_by block can be improved surely.
--
Posted via http://www.ruby-....

Robert Klemme

3/12/2008 3:20:00 PM

0

2008/3/12, Rodrigo Bermejo <rodrigo.bermejo@ps.ge.com>:
>
> a = ['one.jpg', 'two.txt', 'three.pdf','a.txt', 'a.az' , 'a.z']
> a_new=a.sort_by do |x|
> if x =~ /\.txt$/
> 0
> else
> 1
> end
> end
> p a_new
> --> ["a.txt", "two.txt", "one.jpg", "three.pdf", "a.az", "a.z"]
>
> the sort_by block can be improved surely.

Here's one way: sorting with priorities:

irb(main):006:0> a = ['one.jpg', 'two.txt', 'three.pdf','a.txt', 'a.az' , 'a.z']
=> ["one.jpg", "two.txt", "three.pdf", "a.txt", "a.az", "a.z"]
irb(main):007:0> a.sort_by {|s| [/\.txt$/=~s ? 0 : 1, s]}
=> ["a.txt", "two.txt", "a.az", "a.z", "one.jpg", "three.pdf"]

;-)

Kind regards

robert

--
use.inject do |as, often| as.you_can - without end

7stud --

3/12/2008 6:56:00 PM

0

Ma Fe wrote:
> well I dont know where in array i have .txt files but its sure that
> there is just one and i want to put it at first place of array...

> a.select {|i| i =~ /\..txt$/}

That doesn't work.

> b = a.partition {|i| i =~ /\.txt$/}

Neither does that.

This is faster than all the solutions posted so far:


a = ['one.jpg', 'two.kzv', 'a.txt', 'a.az']
new_a = [1]

for elmt in a
if elmt[-3] == ?t
new_a[0] = elmt
else
new_a << elmt
end
end

--output:--
["a.txt", "one.jpg", "two.kzv", "a.az"]
--
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William James

3/12/2008 7:49:00 PM

0

On Mar 12, 1:56 pm, 7stud -- <bbxx789_0...@yahoo.com> wrote:
> Ma Fe wrote:
> > well I dont know where in array i have .txt files but its sure that
> > there is just one and i want to put it at first place of array...

> This is faster than all the solutions posted so far:
>
> a = ['one.jpg', 'two.kzv', 'a.txt', 'a.az']
> new_a = [1]
>
> for elmt in a
> if elmt[-3] == ?t
> new_a[0] = elmt
> else
> new_a << elmt
> end
> end
>
> --output:--
> ["a.txt", "one.jpg", "two.kzv", "a.az"]


Iters = 99_000
a, new_a = nil

t = Time.now
Iters.times{
a = %w(one.jpg two.kzv a.az b.mp3 c.png a.txt d.tif e.gif f.mp4
g.pdf)
new_a = [1]
for elmt in a
if elmt[-4,4] == '.txt'
new_a[0] = elmt
else
new_a << elmt
end
end
}
p Time.now - t

t = Time.now
Iters.times{
a = %w(one.jpg two.kzv a.az b.mp3 c.png a.txt d.tif e.gif f.mp4
g.pdf)
1.upto(a.size-1){|i|
if a[i][-4,4] == '.txt'
a[0],a[i] = a[i],a[0]
break
end
}
}
p Time.now - t

--output--
4.422
3.359

Lua:

when = os.clock()

for _ = 1,99000 do
a = {'one.jpg','two.uzv','a.az','b.mp3','c.png','a.txt',
'd.tif','e.gif','f.mp4','g.pdf'}
for i = 2, #a do
if string.sub( a[i], -4 ) == '.txt' then
a[1],a[i] = a[i],a[1]
end
end
end

print( os.clock() - when )

--output--
0.968

Paul Mckibbin

3/12/2008 8:42:00 PM

0

Ma Fe wrote:
> well I dont know where in array i have .txt files but its sure that
> there is just one and i want to put it at first place of array...

Do you want to sort the array, or just make sure that element is the
first one? If the former case, and speed is an issue, you can just swap
the first element with it which should reduce time of execution. Of
course, I have no empirical evidence of this, but thought that this
question might reduce if that is the case.

Mac
--
Posted via http://www.ruby-....

Todd Benson

3/12/2008 10:33:00 PM

0

On Wed, Mar 12, 2008 at 1:56 PM, 7stud -- <bbxx789_05ss@yahoo.com> wrote:
> Ma Fe wrote:
> > well I dont know where in array i have .txt files but its sure that
> > there is just one and i want to put it at first place of array...
>
>
> > a.select {|i| i =~ /\..txt$/}
>
> That doesn't work.
>
> > b = a.partition {|i| i =~ /\.txt$/}
>
> Neither does that.

Yes, I said all this in the next post.

Todd