# Convert/replace a value of nil with 0? **URL:** \ **Category:** ruby-talk\ **Created:** [22 October 2009 15:24 UTC](https://rubytalk.org/t/convert-replace-a-value-of-nil-with-0/55906 "2009-10-22T15:24:58Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Mmcolli00\_Mom](https://avatars.discourse-cdn.com/v4/letter/m/76d3ee/32.png) [@Mmcolli00\_Mom](https://rubytalk.org/u/Mmcolli00_Mom)\ **Post date:** [22 October 2009 15:24 UTC](https://rubytalk.org/t/convert-replace-a-value-of-nil-with-0/55906/1 "2009-10-22T15:24:58Z")
Do you know how I can convert or replace any value that gets back a 'nil' to 0? For instance, the myArrayVal[0] may or may not contain a number and I want the code to default to 0 if a nil is returned. I have not found any documentation on this. Thanks in advance. MMCOLLI00 > **···** > > -- > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/). ---
**Author:** ![Greg\_Brown1](https://avatars.discourse-cdn.com/v4/letter/g/258eb7/32.png) [@Greg\_Brown1](https://rubytalk.org/u/Greg_Brown1)\ **Post date:** [22 October 2009 15:37 UTC](https://rubytalk.org/t/convert-replace-a-value-of-nil-with-0/55906/2 "2009-10-22T15:37:28Z")
> Do you know how I can convert or replace any value that gets back a > 'nil' to 0? > > For instance, the myArrayVal[0] may or may not contain a number and I > want the code to default to 0 if a nil is returned. I have not found any > documentation on this. > > nil.to\_i =\> 0 > > nil.to\_f =\> 0.0 > **···** > > On Thu, Oct 22, 2009 at 11:24 AM, Mmcolli00 Mom \ wrote: ---
**Author:** ![Jesus\_Gabriel\_y\_Gala](https://avatars.discourse-cdn.com/v4/letter/j/96bed5/32.png) [@Jesus\_Gabriel\_y\_Gala](https://rubytalk.org/u/Jesus_Gabriel_y_Gala)\ **Post date:** [22 October 2009 15:46 UTC](https://rubytalk.org/t/convert-replace-a-value-of-nil-with-0/55906/3 "2009-10-22T15:46:42Z")
irb(main):001:0\> array = =\> irb(main):002:0\> value = array[0] || 0 =\> 0 irb(main):003:0\> value =\> 0 Hope this helps, Jesus. > **···** > > On Thu, Oct 22, 2009 at 5:24 PM, Mmcolli00 Mom \ wrote: > > > Do you know how I can convert or replace any value that gets back a > > 'nil' to 0? > > > > For instance, the myArrayVal[0] may or may not contain a number and I > > want the code to default to 0 if a nil is returned. I have not found any > > documentation on this. ---
**Author:** ![Greg\_Barozzi](https://avatars.discourse-cdn.com/v4/letter/g/f6c823/32.png) [@Greg\_Barozzi](https://rubytalk.org/u/Greg_Barozzi)\ **Post date:** [22 October 2009 17:26 UTC](https://rubytalk.org/t/convert-replace-a-value-of-nil-with-0/55906/4 "2009-10-22T17:26:05Z")
Mmcolli00 Mom wrote: > Do you know how I can convert or replace any value that gets back a > 'nil' to 0? > > For instance, the myArrayVal[0] may or may not contain a number and I > want the code to default to 0 if a nil is returned. I have not found any > documentation on this. If you want to check each value in an array, try: myArrayVal.each\_index do |i|    myArrayVal[i] = 0 if myArrayVal[i].nil? end The each\_index method allows you to iterate through the array and access each element specifically. A less wordy way of writing this would be: myArrayVal.each\_index do |i|    myArrayVal[i] ||= 0 end But using ||= will also convert a value of FALSE to 0, and that may not be a valid operation in your app. Hope this helps and good luck. > **···** > > -- > Posted via [http://www.ruby-forum.com/\](http://www.ruby-forum.com/%5C). ---
**Author:** ![Robert\_Gleeson](https://avatars.discourse-cdn.com/v4/letter/r/dec6dc/32.png) [@Robert\_Gleeson](https://rubytalk.org/u/Robert_Gleeson)\ **Post date:** [23 October 2009 01:14 UTC](https://rubytalk.org/t/convert-replace-a-value-of-nil-with-0/55906/5 "2009-10-23T01:14:47Z")
Mmcolli00 Mom wrote: > Do you know how I can convert or replace any value that gets back a > 'nil' to 0? > > For instance, the myArrayVal[0] may or may not contain a number and I > want the code to default to 0 if a nil is returned. I have not found any > documentation on this. > > Thanks in advance. > MMCOLLI00 If you know the size your array is going to be or the maximum size it will ever be, you could also try: arr = Array.new 5, 0 # =\> [0,0,0,0,0] Hope this helps, Rob. > **···** > > -- > Posted via [http://www.ruby-forum.com/\](http://www.ruby-forum.com/%5C). ---
**Author:** ![Rob\_Biedenharn1](https://avatars.discourse-cdn.com/v4/letter/r/57b2e6/32.png) [@Rob\_Biedenharn1](https://rubytalk.org/u/Rob_Biedenharn1)\ **Post date:** [22 October 2009 15:45 UTC](https://rubytalk.org/t/convert-replace-a-value-of-nil-with-0/55906/6 "2009-10-22T15:45:58Z")
And taking Gregory's information a step further, (myArrayVal[0] || 0) Or you could '|| 9' if you wanted to default nil to 9. When you say "may not contain a number", might you possibly find a string there, too? myArrayVal[0] == 'cat' Just having you think about it. -Rob Rob Biedenharn [http://agileconsultingllc.com](http://agileconsultingllc.com) Rob@AgileConsultingLLC.com > **···** > > On Oct 22, 2009, at 11:37 AM, Gregory Brown wrote: > > > On Thu, Oct 22, 2009 at 11:24 AM, Mmcolli00 Mom \> \ wrote: > > > > > Do you know how I can convert or replace any value that gets back a > > > 'nil' to 0? > > > > > > For instance, the myArrayVal[0] may or may not contain a number and I > > > want the code to default to 0 if a nil is returned. I have not found any > > > documentation on this. > > > > > > nil.to\_i > > > > =\> 0 > > > > > > nil.to\_f > > > > =\> 0.0 ---
**Author:** ![Paul\_Smith1](https://avatars.discourse-cdn.com/v4/letter/p/5daacb/32.png) [@Paul\_Smith1](https://rubytalk.org/u/Paul_Smith1)\ **Post date:** [22 October 2009 16:07 UTC](https://rubytalk.org/t/convert-replace-a-value-of-nil-with-0/55906/7 "2009-10-22T16:07:21Z")
> > Do you know how I can convert or replace any value that gets back a > > 'nil' to 0? > > > > For instance, the myArrayVal[0] may or may not contain a number and I > > want the code to default to 0 if a nil is returned. I have not found any > > documentation on this. > > irb(main):001:0\> array = > =\> > irb(main):002:0\> value = array[0] || 0 > =\> 0 > irb(main):003:0\> value > =\> 0 > > Hope this helps, Though that will of course convert false too. > **···** > > 2009/10/22 Jesús Gabriel y Galán \: > > > On Thu, Oct 22, 2009 at 5:24 PM, Mmcolli00 Mom \ wrote: > > > Jesus. > > -- > Paul Smith > [http://www.nomadicfun.co.uk](http://www.nomadicfun.co.uk) > > paul@pollyandpaul.co.uk ---
**Author:** ![Mmcolli00\_Mom](https://avatars.discourse-cdn.com/v4/letter/m/76d3ee/32.png) [@Mmcolli00\_Mom](https://rubytalk.org/u/Mmcolli00_Mom)\ **Post date:** [22 October 2009 18:43 UTC](https://rubytalk.org/t/convert-replace-a-value-of-nil-with-0/55906/8 "2009-10-22T18:43:51Z")
Thanks you so much for your help!!! MMCOLLI00 > **···** > > -- > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/). ---
**Author:** ![Dev\_Guy](https://avatars.discourse-cdn.com/v4/letter/d/ec9cab/32.png) [@Dev\_Guy](https://rubytalk.org/u/Dev_Guy)\ **Post date:** [23 October 2009 00:15 UTC](https://rubytalk.org/t/convert-replace-a-value-of-nil-with-0/55906/9 "2009-10-23T00:15:24Z")
Greg Barozzi wrote: > Mmcolli00 Mom wrote: > > > Do you know how I can convert or replace any value that gets back a > > 'nil' to 0? > > > > For instance, the myArrayVal[0] may or may not contain a number and I > > want the code to default to 0 if a nil is returned. I have not found any > > documentation on this. > > If you want to check each value in an array, try: > > myArrayVal.each\_index do |i| >    myArrayVal[i] = 0 if myArrayVal[i].nil? > end > > The each\_index method allows you to iterate through the array and access each element specifically. > > A less wordy way of writing this would be: > > myArrayVal.each\_index do |i| >    myArrayVal[i] ||= 0 > end > > But using ||= will also convert a value of FALSE to 0, and that may not be a valid operation in your app. Hope this helps and good luck. Following the examples, if you want to create a new array, you can also do this: irb(main):001:0\> a= irb(main):002:0\> a[3]=5 irb(main):003:0\> a[6]=12.4 irb(main):004:0\> a[7]=22 irb(main):005:0\> p a [nil, nil, nil, 5, nil, nil, 12.4, 22] irb(main):007:0\> b = a.collect { |x| x.nil? ? 0:x } irb(main):008:0\> p b [0, 0, 0, 5, 0, 0, 12.4, 22] > **···** > > -- > Kind Regards, > Rajinder Yadav > > [http://DevMentor.org](http://DevMentor.org) > Do Good ~ Share Freely ---
**Author:** ![Jesus\_Gabriel\_y\_Gala](https://avatars.discourse-cdn.com/v4/letter/j/96bed5/32.png) [@Jesus\_Gabriel\_y\_Gala](https://rubytalk.org/u/Jesus_Gabriel_y_Gala)\ **Post date:** [22 October 2009 16:43 UTC](https://rubytalk.org/t/convert-replace-a-value-of-nil-with-0/55906/10 "2009-10-22T16:43:19Z")
Sure, if you can have in the array things that are not numbers I think to\_i as Gregory suggested should work in general. Or you can do it more explicitly like this: value = array[0].nil? ? 0 : array[0] Jesus. > **···** > > On Thu, Oct 22, 2009 at 6:07 PM, Paul Smith \ wrote: > > > 2009/10/22 Jesús Gabriel y Galán \: > > > > > On Thu, Oct 22, 2009 at 5:24 PM, Mmcolli00 Mom \ wrote: > > > > > > > Do you know how I can convert or replace any value that gets back a > > > > 'nil' to 0? > > > > > > > > For instance, the myArrayVal[0] may or may not contain a number and I > > > > want the code to default to 0 if a nil is returned. I have not found any > > > > documentation on this. > > > > > > irb(main):001:0\> array = > > > =\> > > > irb(main):002:0\> value = array[0] || 0 > > > =\> 0 > > > irb(main):003:0\> value > > > =\> 0 > > > > > > Hope this helps, > > > > Though that will of course convert false too. ---
**Author:** ![Colin\_Bartlett1](https://avatars.discourse-cdn.com/v4/letter/c/dbc845/32.png) [@Colin\_Bartlett1](https://rubytalk.org/u/Colin_Bartlett1)\ **Post date:** [25 October 2009 10:26 UTC](https://rubytalk.org/t/convert-replace-a-value-of-nil-with-0/55906/11 "2009-10-25T10:26:29Z")
More possibilities? (1) If you just want an array "accessor" without changing the array itself and without setting up a new array, then adapting Jesús Gabriel y Galán's post: class Object   def nil\_to( value ); self.nil? ? value : self ; end end a[5] = nil ; a[5].nil\_to( 0 ) #=\> 0 a[7] = false ; a[7].nil\_to( 0 ) #=\> false or even: class Array   def at\_with\_nil\_to(i, value); (obj = self[i]).nil? ? value : obj; end end (2) If you want to modify the array itself, instead of creating a new array, then adapting Rajinder Yadav's post you can do:   arr.collect! { |obj| obj.nil? ? 0 : obj } or use "map!" which is a synonym for "collect!". Using "collect!" seems to be faster than using "each\_with\_index" and modifying the appropriate elements. Is that what people would expect? I ask because for similar things which modified arrays "in place" I used to use "each\_with\_index" type code until I understood what collect!/map! did. ---
**Author:** ![Matt\_Williams](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@Matt\_Williams](https://rubytalk.org/u/Matt_Williams)\ **Post date:** [22 October 2009 17:25 UTC](https://rubytalk.org/t/convert-replace-a-value-of-nil-with-0/55906/12 "2009-10-22T17:25:53Z")
Or, being very evil...... class Array    idx = self.instance\_method(:)    define\_method(:) do |x|      n=idx.bind(self).call(x)      return n.nil? ? 0 : n    end end (this is based off of [Jay Fields' Thoughts: Ruby: Alias method alternative](http://blog.jayfields.com/2006/12/ruby-alias-method-alternative.html) ) Matt > **···** > > On Fri, 23 Oct 2009, [ISO-8859-1] Jesús Gabriel y Galán wrote: > > > On Thu, Oct 22, 2009 at 6:07 PM, Paul Smith \ wrote: > > > > > 2009/10/22 Jesús Gabriel y Galán \: > > > > > > > On Thu, Oct 22, 2009 at 5:24 PM, Mmcolli00 Mom \ wrote: > > > > > > > > > Do you know how I can convert or replace any value that gets back a > > > > > 'nil' to 0? > > > > > > > > > > For instance, the myArrayVal[0] may or may not contain a number and I > > > > > want the code to default to 0 if a nil is returned. I have not found any > > > > > documentation on this. > > > > > > > > irb(main):001:0\> array = > > > > =\> > > > > irb(main):002:0\> value = array[0] || 0 > > > > =\> 0 > > > > irb(main):003:0\> value > > > > =\> 0 > > > > > > > > Hope this helps, > > > > > > Though that will of course convert false too. > > > > Sure, if you can have in the array things that are not numbers I think > > to\_i as Gregory suggested should work in general. Or you can do it > > more explicitly like this: > > > > value = array[0].nil? ? 0 : array[0]