Convert day of year to month, day

Ruby
1

Hi,

What’s the “ruby way” to go from a date/time format that is “Year
Day_of_Year time” to “Year Month Day”. E.g. I want to convert
year=2008, day_of_year=095, frequently represented as “2008-095” to it’s
more usual format “2008-04-04”. I’ve been playing with the Time class
and it’s methods and found nifty ways to get yday, e.g.
Time.now.utc.yday, but how do I easily go backwards w/o writing my own
simple converter?

R

2

On Apr 4, 2008, at 9:38 AM, Rob R. wrote:

What’s the “ruby way” to go from a date/time format that is “Year
Day_of_Year time” to “Year Month Day”. E.g. I want to convert
year=2008, day_of_year=095, frequently represented as “2008-095” to
it’s
more usual format “2008-04-04”. I’ve been playing with the Time class
and it’s methods and found nifty ways to get yday, e.g.
Time.now.utc.yday, but how do I easily go backwards w/o writing my own
simple converter?

How’s this?

require “date”
=> true

Date.strptime(“2008-095”, “%Y-%j”).to_s
=> “2008-04-04”

James Edward G. II

3

On Apr 4, 2008, at 8:38 AM, Rob R. wrote:

Hi,

What’s the “ruby way” to go from a date/time format that is “Year
Day_of_Year time” to “Year Month Day”. E.g. I want to convert
year=2008, day_of_year=095, frequently represented as “2008-095” to
it’s
more usual format “2008-04-04”. I’ve been playing with the Time class
and it’s methods and found nifty ways to get yday, e.g.
Time.now.utc.yday, but how do I easily go backwards w/o writing my own
simple converter?

R

hi rob-

james example is good - you might find this method quite useful with
julian days to:

p Date.ordinal(2008,1).ctime #=> “Tue Jan 1 00:00:00 2008”

cheers

a @ http://codeforpeople.com/

4

ara.t.howard wrote:

On Apr 4, 2008, at 8:38 AM, Rob R. wrote:

Hi,

What’s the “ruby way” to go from a date/time format that is “Year
Day_of_Year time” to “Year Month Day”. E.g. I want to convert
year=2008, day_of_year=095, frequently represented as “2008-095” to
it’s
more usual format “2008-04-04”. I’ve been playing with the Time class
and it’s methods and found nifty ways to get yday, e.g.
Time.now.utc.yday, but how do I easily go backwards w/o writing my own
simple converter?

R

hi rob-

james example is good - you might find this method quite useful with
julian days to:

p Date.ordinal(2008,1).ctime #=> “Tue Jan 1 00:00:00 2008”

cheers

a @ http://codeforpeople.com/

Wicked, thanks Ara!

Caution to the wind; I’m building my own 1.8.6 to experiment with.

Rob

5

On Apr 4, 2008, at 9:20 AM, Rob R. wrote:

Maybe my version of Ruby (1.8.1) is too old. The computer in question
is managed by the network pirates and unlikely to be upgraded. This
is
a noob thought, but is there a way for me to locally upgrade the Date
class, ala a Ruby Gem?

yyyy, jjj, *ignored = yourdate.split ‘-’

date = Date.ordinal Integer(yyyy), Integer(jjj)

p date

a @ http://codeforpeople.com/

6

On Apr 4, 2008, at 9:24 AM, Rob R. wrote:

Caution to the wind; I’m building my own 1.8.6 to experiment with.

put it on NFS - then just use it everywhere - bugger sysadmins

a @ http://codeforpeople.com/

7

James G. wrote:

On Apr 4, 2008, at 9:38 AM, Rob R. wrote:

What’s the “ruby way” to go from a date/time format that is “Year
Day_of_Year time” to “Year Month Day”. E.g. I want to convert
year=2008, day_of_year=095, frequently represented as “2008-095” to
it’s
more usual format “2008-04-04”. I’ve been playing with the Time class
and it’s methods and found nifty ways to get yday, e.g.
Time.now.utc.yday, but how do I easily go backwards w/o writing my own
simple converter?

How’s this?

require “date”
=> true

Date.strptime(“2008-095”, “%Y-%j”).to_s
=> “2008-04-04”

James Edward G. II

Good idea, but doesn’t work for me:
irb(main):065:0> Date.strptime(“2008-095”, “%Y-%J”).to_s
ArgumentError: invalid date
from /usr/lib/ruby/1.8/date.rb:650:in new_with_hash' from /usr/lib/ruby/1.8/date.rb:675:instrptime’
from (irb):65
from :0

Maybe my version of Ruby (1.8.1) is too old. The computer in question
is managed by the network pirates and unlikely to be upgraded. This is
a noob thought, but is there a way for me to locally upgrade the Date
class, ala a Ruby Gem?

R

8

James G. wrote:

How’s this?

require “date”
=> true

Date.strptime(“2008-095”, “%Y-%j”).to_s
=> “2008-04-04”

James Edward G. II

Now that is an awesome little method I didn’t know about. Thanks James.