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rubydatetimehash
Jamex
Jamex

Reputation: 1222

Ruby - DateTime library parsing error (a bug?)

Can someone verify my datetime conversion error.

What I have is a hash of days of the week as number fixnum keys generated from the Date library. I sorted the hash and I want to convert the fixnum keys to days of the week (ie 0 --> Sunday)

My hash output is {3=>7, 2=>1, 4=>2} ( using dh=Hash[dh.sort] I would get {2=>1, 3=>7, 4=>2} )

after the sort, I try to perform a .each do 

dh = {3=>7, 2=>1, 4=>2}
dh=Hash[dh.sort]

dh.each do |day,reg|
    #puts day.class
    #puts day="3" # This works

    day=day.to_s  ##<<== problem here: error "invalid date" when evaluated by strptime
                  ## if don't do day.to_s conversion, error "can't convert fixnum into string"
    #day="#{day}" ## does not work either

    wday= DateTime.strptime(day,'%d') ##<<== and problem here

    puts wday.strftime("%a")
    puts wday   
      end

so the day variable is a fixnum. So no matter what I do to the day variable (convert to string, or leave it as fixnum), the strptime does not work.

It does not matter if I make up another variable such as xyz = day.to_s, the xyz variable would still get error out by the strptime method.

But if I manually assign the day variable a string value day="3", then the strptime would work.

Any insight into this problem, is this a bug?

Upvotes: 0

Views: 452

Answers (3)

Jamex
Jamex

Reputation: 1222

Editted to reflect the correct cause pointed out.

OK, I figured out the problem

I originally used the 

datestamp = DateTime.strptime(datestr, '%m/%d/%y %H:%M')

and the datestamp.wday to create a hash with #wday values as the keys. These #wday values are numbers from 0-6 to represent Sunday-Saturday.

When I used the DateTime.strptime(day,'%d'), I should had used the %w switch. The correct statement should have been DateTime.strptime(day.to_s,'%w')

Upvotes: 0

David Unric
David Unric

Reputation: 7719

If I do understand you correctly, you are confusing the proper datetime format. If you need to handle the weekday number you need to put %w instead of %d ie. day of the month.

dh = {3=>7, 2=>1, 4=>2, 0=>5}.sort
dh.each do |day,reg|
  day=day.to_s
  wday= DateTime.strptime(day,'%w')
  puts wday.strftime("%a")
end

# Sun
# Tue
# Wed
# Thu

Upvotes: 1

Roman Kiselenko
Roman Kiselenko

Reputation: 44370

This work

=> dh = {3=>2, 2=>7}
=> {3=>2, 2=>7}
=> dh = Hash[dh.sort]
=> {2=>7, 3=>2}
=> dh.each { |day,reg| DateTime.strptime(day,'%d') }
=> TypeError: no implicit conversion of Fixnum into String
=> dh.each { |day,reg| puts DateTime.strptime(day.to_s,'%d') }
=> 2013-12-02T00:00:00+00:00
=> 2013-12-03T00:00:00+00:00
=> {2=>7, 3=>2}

Upvotes: 0

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