Array uniq

Ruby
1

I am having some troubles with the uniq method for arrays. This is a
typical example of my data set, which I want to remove the duplicates
from.

TueAug052008
TueAug052008
TueAug052008
TueAug052008

Its clear to see the set of data above has 4 identical values and should
therefore only have remaining after applying array.uniq to this array.
It has become obvious this doesn’t work and uniq doesn’t remove any
duplicates it just pushes the data out as it finds it full of
dupelictes. Is this a problem with the data set? This is my code:

value= timeDone.to_s
dateCheck.push value.gsub(/\s/, ‘’)[0…7] + value[26…30]
date = dateCheck.uniq
@alerts.push(date)

Many thanks

2

On Thu, 12 Feb 2009, Stuart L. wrote:

therefore only have remaining after applying array.uniq to this array.
It has become obvious this doesn’t work and uniq doesn’t remove any
duplicates it just pushes the data out as it finds it full of
dupelictes. Is this a problem with the data set? This is my code:

value= timeDone.to_s
dateCheck.push value.gsub(/\s/, ‘’)[0…7] + value[26…30]
date = dateCheck.uniq
@alerts.push(date)

Array#uniq does work:

a = Array.new(4) { “TueAug052008” }
=> [“TueAug052008”, “TueAug052008”, “TueAug052008”, “TueAug052008”]
a.uniq
=> [“TueAug052008”]

So there must be something else going on. Maybe stray whitespace? How
are you determining that the operation didn’t work?

David

–
David A. Black / Ruby Power and Light, LLC
Ruby/Rails consulting & training: http://www.rubypal.com
Coming in 2009: The Well-Grounded Rubyist (The Well-Grounded Rubyist)

http://www.wishsight.com => Independent, social wishlist management!

3

On Wed, Feb 11, 2009 at 3:51 PM, Stuart L. <
[email protected]> wrote:

therefore only have remaining after applying array.uniq to this array.

It’s hard to say what your code does without more context, but…

Here’s an attempt to get at the essence of your logic

value = “Hi”
dateCheck = []
alerts = []
5.times do
dateCheck.push value
puts “dateCheck is now #{dateCheck.inspect}”
date = dateCheck.uniq
puts “date is #{date.inspect}”
alerts.push(date)
end
puts “at end dateCheck is #{dateCheck.inspect}”
puts “and alerts is #{alerts.inspect}”

which produces:

dateCheck is now [“Hi”]
date is [“Hi”]
dateCheck is now [“Hi”, “Hi”]
date is [“Hi”]
dateCheck is now [“Hi”, “Hi”, “Hi”]
date is [“Hi”]
dateCheck is now [“Hi”, “Hi”, “Hi”, “Hi”]
date is [“Hi”]
dateCheck is now [“Hi”, “Hi”, “Hi”, “Hi”, “Hi”]
date is [“Hi”]
at end dateCheck is [“Hi”, “Hi”, “Hi”, “Hi”, “Hi”]
and alerts is [[“Hi”], [“Hi”], [“Hi”], [“Hi”], [“Hi”]]

Maybe this is more like what you want?

value = “Hi”
dateCheck = []
alerts = []
5.times do
dateCheck.push value
puts “dateCheck is now #{dateCheck.inspect}”
dateCheck.uniq!
puts “dateCheck is now #{dateCheck.inspect}”
end
puts “at end dateCheck is #{dateCheck.inspect}”

dateCheck is now [“Hi”]
dateCheck is now [“Hi”]
dateCheck is now [“Hi”, “Hi”]
dateCheck is now [“Hi”]
dateCheck is now [“Hi”, “Hi”]
dateCheck is now [“Hi”]
dateCheck is now [“Hi”, “Hi”]
dateCheck is now [“Hi”]
dateCheck is now [“Hi”, “Hi”]
dateCheck is now [“Hi”]
at end dateCheck is [“Hi”]

–
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Twitter: http://twitter.com/RickDeNatale

4

2009/2/11 Stuart L. [email protected]:

 time = event.time_written.to_s
 dateCheck = [time.gsub(/\s/, '')[0..7] + time[26..29]]
 printdata = [dateCheck]
 @alerts.push printdata.uniq

Stuart, in this code you have an array with exactly one element, so
#uniq returns the original array. Can you add the line “p printdata”
and show us the output?

Regards,
Pit

5

Thanks for the response.

I remove whitespace with gsub. My original data set:

TueAug052008
WedAug062008
TueAug052008
WedAug062008
WedAug062008

Is returned after my code exactly the same, I am expecting

WedAug062008
TueAug052008

I have dumbed the code down to see what you think:

  time = event.time_written.to_s
  dateCheck = [time.gsub(/\s/, '')[0..7] + time[26..29]]
  printdata = [dateCheck]
  @alerts.push printdata.uniq

Many thanks

David A. Black wrote:

On Thu, 12 Feb 2009, Stuart L. wrote:

therefore only have remaining after applying array.uniq to this array.
It has become obvious this doesn’t work and uniq doesn’t remove any
duplicates it just pushes the data out as it finds it full of
dupelictes. Is this a problem with the data set? This is my code:

value= timeDone.to_s
dateCheck.push value.gsub(/\s/, ‘’)[0…7] + value[26…30]
date = dateCheck.uniq
@alerts.push(date)

Array#uniq does work:

a = Array.new(4) { “TueAug052008” }
=> [“TueAug052008”, “TueAug052008”, “TueAug052008”, “TueAug052008”]
a.uniq
=> [“TueAug052008”]

So there must be something else going on. Maybe stray whitespace? How
are you determining that the operation didn’t work?

David

–
David A. Black / Ruby Power and Light, LLC
Ruby/Rails consulting & training: http://www.rubypal.com
Coming in 2009: The Well-Grounded Rubyist (The Well-Grounded Rubyist)

http://www.wishsight.com => Independent, social wishlist management!

6

I want something simpler than that to be honest. I just want to get rid
of all duplicate entries in the data set and leave just one of each
unique value in my array.

Also, FYI .uniq returns all the values as they are and doesn’t remove
duplicates. .uniq! gets rid of all the values and leaves me with no data
at all

7

Forgive me. What does that line do? The output is listed earlier in the
thread.

Many thanks

Pit C. wrote:

2009/2/11 Stuart L. [email protected]:

 time = event.time_written.to_s
 dateCheck = [time.gsub(/\s/, '')[0..7] + time[26..29]]
 printdata = [dateCheck]
 @alerts.push printdata.uniq

Stuart, in this code you have an array with exactly one element, so
#uniq returns the original array. Can you add the line “p printdata”
and show us the output?

Regards,
Pit

8

Hi –

On Thu, 12 Feb 2009, Stuart L. wrote:

Is returned after my code exactly the same, I am expecting

WedAug062008
TueAug052008

I have dumbed the code down to see what you think:

 time = event.time_written.to_s
 dateCheck = [time.gsub(/\s/, '')[0..7] + time[26..29]]
 printdata = [dateCheck]
 @alerts.push printdata.uniq

printdata.uniq is the same items as printdata, because printdata only
contains one item. So you’re doing this:

dateCheck = [“string”]
printdata = [[“string”]]
@alerts.push [[“string”]].uniq

I don’t how deeply nested you want your arrays, but if @alerts is the
final product and you want it uniq, you could run @alerts.uniq! at the
end, or do something like:

@alerts.push printdata unless @alerts.include?(printdata)

David

–
David A. Black / Ruby Power and Light, LLC
Ruby/Rails consulting & training: http://www.rubypal.com
Coming in 2009: The Well-Grounded Rubyist (The Well-Grounded Rubyist)

http://www.wishsight.com => Independent, social wishlist management!

9

2009/2/11 Stuart L. [email protected]:

I want something simpler than that to be honest. I just want to get rid
of all duplicate entries in the data set and leave just one of each
unique value in my array.

Also, FYI .uniq returns all the values as they are and doesn’t remove
duplicates. .uniq! gets rid of all the values and leaves me with no data
at all

Can you show us the contents of the array and the result of #uniq? For
example:

my_array =

p my_array
p my_array.uniq

Regards,
Pit

10

On Wed, Feb 11, 2009 at 4:51 PM, Stuart L. <
[email protected]> wrote:

I want something simpler than that to be honest. I just want to get rid
of all duplicate entries in the data set and leave just one of each
unique value in my array.

I guess you are replying to me. Perhaps it would be best not to cut
everything in the reply.

Also, FYI .uniq returns all the values as they are and doesn’t remove
duplicates. .uniq! gets rid of all the values and leaves me with no data
at all

No, I know exactly what Array#uniq! does:
------------------------------------------------------------ Array#uniq!
array.uniq! → array or nil

 Removes duplicate elements from self. Returns nil if no changes
 are made (that is, no duplicates are found).

    a = [ "a", "a", "b", "b", "c" ]
    a.uniq!   #=> ["a", "b", "c"]
    b = [ "a", "b", "c" ]
    b.uniq!   #=> nil

As I said I wasn’t sure what you were trying to accomplish and what
object
should eliminate duplicates.

If you think about my example a bit, I suspect you’ll be able to suss it
out.

–
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Twitter: http://twitter.com/RickDeNatale

11

That makes sense but how do I avoid this? I cant see how. I need to
dedupe before the data goes into @alerts.

David A. Black wrote:

Hi –

On Thu, 12 Feb 2009, Stuart L. wrote:

Is returned after my code exactly the same, I am expecting

WedAug062008
TueAug052008

I have dumbed the code down to see what you think:

 time = event.time_written.to_s
 dateCheck = [time.gsub(/\s/, '')[0..7] + time[26..29]]
 printdata = [dateCheck]
 @alerts.push printdata.uniq

printdata.uniq is the same items as printdata, because printdata only
contains one item. So you’re doing this:

dateCheck = [“string”]
printdata = [[“string”]]
@alerts.push [[“string”]].uniq

I don’t how deeply nested you want your arrays, but if @alerts is the
final product and you want it uniq, you could run @alerts.uniq! at the
end, or do something like:

@alerts.push printdata unless @alerts.include?(printdata)

David

–
David A. Black / Ruby Power and Light, LLC
Ruby/Rails consulting & training: http://www.rubypal.com
Coming in 2009: The Well-Grounded Rubyist (The Well-Grounded Rubyist)

http://www.wishsight.com => Independent, social wishlist management!

12

Ok

This

dateCheck = [time.gsub(/\s/, ‘’)[0…7] + time[26…29]]
#printdata.push(dateCheck)
@alerts.push dateCheck

gets me:

TueAug052008
TueAug052008
TueAug052008
WedAug062008
WedAug062008
TueAug052008

and this

dateCheck = [time.gsub(/\s/, ‘’)[0…7] + time[26…29]]
#printdata.push(dateCheck)
@alerts.push dateCheck.uniq

gets me

TueAug052008
TueAug052008
TueAug052008
WedAug062008
WedAug062008
TueAug052008

Same data for both. When I do uniq! I get nothing

Many thanks

Pit C. wrote:

2009/2/11 Stuart L. [email protected]:

I want something simpler than that to be honest. I just want to get rid
of all duplicate entries in the data set and leave just one of each
unique value in my array.

Also, FYI .uniq returns all the values as they are and doesn’t remove
duplicates. .uniq! gets rid of all the values and leaves me with no data
at all

Can you show us the contents of the array and the result of #uniq? For
example:

my_array =

p my_array
p my_array.uniq

Regards,
Pit

13

2009/2/11 Stuart L. [email protected]:

TueAug052008
WedAug062008
WedAug062008
TueAug052008

This is not what I suggested. I just wanted the output of

p dateCheck
p dateCheck.uniq

and I’m sure we can tell you immediately what’s going wrong.

If you don’t want to do this for some reason, I repeat what I’ve
written before: you still have an array with just one element: a
string of size 12. So #uniq returns the same array. But if you still
say that you get six lines of output, I suspect that you execute the
code you’ve shown in a loop and that you are filling the array
@alerts. If this is the case, you are using #uniq at the wrong place.
Either do @alerts.uniq after the loop or use the code David has
shown you.

Regards,
Pit

14

Hi –

On Thu, 12 Feb 2009, Stuart L. wrote:

@alerts.push [[“string”]].uniq

I don’t how deeply nested you want your arrays, but if @alerts is the
final product and you want it uniq, you could run @alerts.uniq! at the
end, or do something like:

@alerts.push printdata unless @alerts.include?(printdata)

That makes sense but how do I avoid this? I cant see how. I need to
dedupe before the data goes into @alerts.

I’m sorry but I’m getting confused. You’ve got dateCheck, which is a
string, and printdata, which is an array containing only that one
string (so .uniq is not an issue). The only point at which you have
the possibility of adding non-uniq data to an array is the
@alerts.push operation, and I specifically suggesting that you not put
the data in there if it’s already there.

David

–
David A. Black / Ruby Power and Light, LLC
Ruby/Rails consulting & training: http://www.rubypal.com
Coming in 2009: The Well-Grounded Rubyist (The Well-Grounded Rubyist)

http://www.wishsight.com => Independent, social wishlist management!

15

Sorry I seemed to have missed your first post. I have tried this code
which is already in a loop so I have

@date = []
@dateCheck = []
@alerts = []
array do |event|

time = event.time_written.to_s
@date = time.gsub(/\s/, ‘’)[0…7] + time[26…29]
@dateCheck.push @date
@alerts.push(@date) unless @alerts.include?(@date)

Inside my loop I have the same problem, outside the loop I get just one
entry which again is not what I need. I also tried before I posted on
the forum putting array.uniq outside of the loop and I just got one
entry again which is incorrect.

Rick Denatale wrote:

On Wed, Feb 11, 2009 at 5:33 PM, Stuart L. <
[email protected]> wrote:

That makes sense but how do I avoid this? I cant see how. I need to
dedupe before the data goes into @alerts.

David and I are trying to tell you the same thing.

My last attempt to get through

date = “TueAug052008”
dateCheck = []
alerts = []
5.times do
dateCheck.push date
alerts.push(date) unless alerts.include?(date)
end

puts “at end alerts is #{alerts.inspect}”
puts " and dateCheck is #{dateCheck.inspect}"

at end alerts is [“TueAug052008”]
and dateCheck is [“TueAug052008”, “TueAug052008”, “TueAug052008”,
“TueAug052008”, “TueAug052008”]

–
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Twitter: http://twitter.com/RickDeNatale

16

Up and running now thanks

Rick Denatale wrote:

On Wed, Feb 11, 2009 at 5:33 PM, Stuart L. <
[email protected]> wrote:

That makes sense but how do I avoid this? I cant see how. I need to
dedupe before the data goes into @alerts.

David and I are trying to tell you the same thing.

My last attempt to get through

date = “TueAug052008”
dateCheck = []
alerts = []
5.times do
dateCheck.push date
alerts.push(date) unless alerts.include?(date)
end

puts “at end alerts is #{alerts.inspect}”
puts " and dateCheck is #{dateCheck.inspect}"

at end alerts is [“TueAug052008”]
and dateCheck is [“TueAug052008”, “TueAug052008”, “TueAug052008”,
“TueAug052008”, “TueAug052008”]

–
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Twitter: http://twitter.com/RickDeNatale

17

On Wed, Feb 11, 2009 at 5:33 PM, Stuart L. <
[email protected]> wrote:

That makes sense but how do I avoid this? I cant see how. I need to
dedupe before the data goes into @alerts.

David and I are trying to tell you the same thing.

My last attempt to get through

date = “TueAug052008”
dateCheck = []
alerts = []
5.times do
dateCheck.push date
alerts.push(date) unless alerts.include?(date)
end

puts “at end alerts is #{alerts.inspect}”
puts " and dateCheck is #{dateCheck.inspect}"

at end alerts is [“TueAug052008”]
and dateCheck is [“TueAug052008”, “TueAug052008”, “TueAug052008”,
“TueAug052008”, “TueAug052008”]

–
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Twitter: http://twitter.com/RickDeNatale

18

Use uniq! Which modifies the receiver in place.

Blog: http://random8.zenunit.com/
Learn rails: http://sensei.zenunit.com/

On 12/02/2009, at 7:51 AM, Stuart L.
<[email protected]