Sorting Array Of Dates
Chandu Chandu
just started with some examples
i have array
date = ['12/09/2007','06/06/2004','10/06/2005']
i wanted to sort dates in ascending order i.e
['06/06/2004','10/06/2005','12/09/2007']
tried using
p data.sort
could any one explain me whether there is built in class or need to
break tha date string
yyyy mm dd and compare ..
regards
chandu
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Peña, Botp
# i wanted to sort dates in ascending order i.e
# ['06/06/2004','10/06/2005','12/09/2007']
# could any one explain me whether there is built in class or need to
# break tha date string
# yyyy mm dd and compare ..
you have the idea. just continue reading more on ruby..
eg,
> date = ['12/09/2007','06/06/2004','10/06/2005']
> date.sort_by{|d| m,d,y=d.split("/");[y,m,d]}
=> ["06/06/2004", "10/06/2005", "12/09/2007"]
Craig Demyanovich
Works for me in IRB:
>> date = ['12/09/2007','06/06/2004','10/06/2005']
=> ["12/09/2007", "06/06/2004", "10/06/2005"]
>> p date.sort
["06/06/2004", "10/06/2005", "12/09/2007"]
=> nil
If it didn't work for you, could it be that you assigned to date but called
sort on data?
Regards,
Craig
Robert Klemme
> Hi, Everyone I am a newbie to ruby....
>
> just started with some examples
>
> i have array
>
> date = ['12/09/2007','06/06/2004','10/06/2005']
This is not an array of dates - it's an array of strings.
> i wanted to sort dates in ascending order i.e
> ['06/06/2004','10/06/2005','12/09/2007']
>
> tried using
>
> p data.sort
>
> could any one explain me whether there is built in class or need to
> break tha date string
If these are dates you should use Date.
irb(main):005:0> date = ['12/09/2007','06/06/2004','10/06/2005']
=> ["12/09/2007", "06/06/2004", "10/06/2005"]
irb(main):006:0> real = date.map {|s| Date.parse s}
=> [#<Date: 4908887/2,0,2299161>, #<Date: 4906325/2,0,2299161>,
#<Date: 4907299/2,0,2299161>]
irb(main):007:0> puts real.sort
2004-06-06
2005-10-06
2007-12-09
=> nil
If for some serious reason you cannot use Date you should at least sort by Date:
irb(main):009:0> puts date.sort_by {|s| Date.parse s}
06/06/2004
10/06/2005
12/09/2007
=> nil
irb(main):010:0>
You need to require 'date' for this to work.
Kind regards
robert
--
remember.guy do |as, often| as.you_can - without end
Brian Candler
> i have array
>
> date = ['12/09/2007','06/06/2004','10/06/2005']
>
> i wanted to sort dates in ascending order i.e
> ['06/06/2004','10/06/2005','12/09/2007']
Apart from the other solutions mentioned, you could also just use ISO
dates instead:
date = ['2007-09-12','2004-06-06','2005-06-10']
http://en.wikipedia.org/wiki/ISO_8601#Calendar_dates
As well as sorting natively, this also has the advantage of being
absolutely clear which part is the month and which is the day. (In your
example, I can't tell whether you are using American middle-endian dates
or not)
Regards,
Brian.
Josef 'Jupp' Schugt
wrote:
> Hi, Everyone I am a newbie to ruby....
>
> just started with some examples
>
> i have array
>
> date = ['12/09/2007','06/06/2004','10/06/2005']
>
> i wanted to sort dates in ascending order i.e
> ['06/06/2004','10/06/2005','12/09/2007']
you forgot to mention if the date format is reasonable (dd/mm/yyyy) or not
(mm/dd/yyyy) - reasonable in the sense that the parts have an ascending or
descending significance and not an arbitrary one.
Anyway, here's a solution for both cases:
def datecmp(a, b, reasonable = true)
arra, arrb = a.split('/'), b.split('/')
cmp = (arra[2] <=> arrb[2])
return cmp if (cmp = (arra[2] <=> arrb[2])) != 0
if reasonable
(cmp = (arra[0] <=> arrb[0])) != 0 ? cmp : (arra[1] <=> arrb[1])
else
(cmp = (arra[1] <=> arrb[1])) != 0 ? cmp : (arra[0] <=> arrb[0])
end
end
date = ['12/01/2007', '11/02/2007', '11/11/2005']
puts "reasonable date format"
puts date.sort { |a, b| datecmp(a, b) }
puts "\nno reasonable date format"
puts date.sort { |a, b| datecmp(a, b, false) }
that results in
reasonable date format
11/11/2005
11/02/2007
12/01/2007
no reasonable date format
11/11/2005
12/01/2007
11/02/2007
but besides that the normal date format is yyyy-mm-dd.
I don't know about the situation in other countries but in Germany the
date format you SHOULD use (in an RFC sense, the DIN standard says so) is
that ISO standard form. Other formats are only tolerable but not
desireable. Which does not mean that many Germans use that format. You
hear me frequently protest against forms that still use antiquated date
formats :)
Josef 'Jupp' Schugt
--
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Brian Candler
> def datecmp(a, b, reasonable = true)
> arra, arrb = a.split('/'), b.split('/')
> cmp = (arra[2] <=> arrb[2])
> return cmp if (cmp = (arra[2] <=> arrb[2])) != 0
> if reasonable
> (cmp = (arra[0] <=> arrb[0])) != 0 ? cmp : (arra[1] <=> arrb[1])
> else
> (cmp = (arra[1] <=> arrb[1])) != 0 ? cmp : (arra[0] <=> arrb[0])
> end
> end
>
> date = ['12/01/2007', '11/02/2007', '11/11/2005']
> puts "reasonable date format"
> puts date.sort { |a, b| datecmp(a, b) }
> puts "\nno reasonable date format"
> puts date.sort { |a, b| datecmp(a, b, false) }
I think you got "reasonable" and "unreasonable" reversed (unless you are
American :-)
Here is a shorter solution:
MapR = lambda { |x| x.split('/').values_at(2,1,0) }
MapU = lambda { |x| x.split('/').values_at(2,0,1) }
date = ['12/01/2007', '11/02/2007', '11/11/2005']
puts "reasonable date format"
puts date.sort_by(&MapR)
puts "\nno reasonable date format"
puts date.sort_by(&MapU)
William James
MAP_R = proc{|x| x.split('/').reverse }
MAP_U = proc{|x| y=x.split('/'); [y.pop,y] }
dates = %w(12/01/2007 11/02/2007 11/11/2005)
puts "reasonable date format"
puts dates.sort_by(&MAP_R)
puts "unreasonable date format"
puts dates.sort_by(&MAP_U)
Josef 'Jupp' Schugt
wrote:
> I think you got "reasonable" and "unreasonable" reversed (unless you are
> American :-)
oops, you are right :) That much on quick hacks... ^^