Problem with reading file

ruby-talk
1

Hi folks,

I read a file in the following format,extract the second column only,
and push them into an array. My problem is that Ruby reads them as
strings(based on array.inspect) but not as numbers so it is impossible
for me to do the calculation. Any comments?

Thanks,

Li

###filen name: array.text

A 1 B
A 2 B
A 3 B
A 4 B
A 5 B
A 6 B

...

###script

equire 'enumerator'

array=Array.new

File.open('array.text').each{|line| array<<line.split(/\t/)[1]}

#puts array.inspect
array.each_slice(3){|slice|
                   average=(slice[0]+slice[1]+slice[2])/(3.0)
                   puts average
                }

###output from screen

C:/Ruby/self/file6.rb:8: undefined method `/' for "123":String
(NoMethodError)
        from
c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
`each_slice'
        from C:/Ruby/self/file6.rb:7:in `each'
        from C:/Ruby/self/file6.rb:7:in `each_slice'
        from C:/Ruby/self/file6.rb:7

···

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2

You need to tell Ruby to coerce the strings into integers.

array =

File.open('array.text') do |file|
  file.each_line do |line|
    array << line.split[1].to_i
  end
end

array.each_slice(3) do |triplet|
  average = (slice[0]+slice[1]+slice[2])/3.0
  puts average
end

···

On 10/20/06, Li Chen <chen_li3@yahoo.com> wrote:

Hi folks,

I read a file in the following format,extract the second column only,
and push them into an array. My problem is that Ruby reads them as
strings(based on array.inspect) but not as numbers so it is impossible
for me to do the calculation. Any comments?

Thanks,

Li

###filen name: array.text

A 1 B
A 2 B
A 3 B
A 4 B
A 5 B
A 6 B

...

###script

equire 'enumerator'

array=Array.new

File.open('array.text').each{|line| array<<line.split(/\t/)[1]}

#puts array.inspect
array.each_slice(3){|slice|
                   average=(slice[0]+slice[1]+slice[2])/(3.0)
                   puts average
                }

###output from screen

C:/Ruby/self/file6.rb:8: undefined method `/' for "123":String
(NoMethodError)
        from
c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
`each_slice'
        from C:/Ruby/self/file6.rb:7:in `each'
        from C:/Ruby/self/file6.rb:7:in `each_slice'
        from C:/Ruby/self/file6.rb:7

3

This can be done by an awk style 1liner :slight_smile:

18:12:44 [Temp]: cat data
A 1 B
A 2 B
A 3 B
A 4 B
A 5 B
A 6 B
18:13:18 [Temp]: ruby -aF\\t -n -r enumerator -e 'BEGIN{$a=}; $a<<$F[1].to_i; END{ $a.each_slice(3){|sl| p sl.inject(0){|a,b|a+b}/3.0}}' data
2.0
5.0
18:13:34 [Temp]:

Kind regards

  robert

···

On 20.10.2006 17:25, Li Chen wrote:

Hi folks,

I read a file in the following format,extract the second column only, and push them into an array. My problem is that Ruby reads them as strings(based on array.inspect) but not as numbers so it is impossible for me to do the calculation. Any comments?

Thanks,

Li

###filen name: array.text

A 1 B
A 2 B
A 3 B
A 4 B
A 5 B
A 6 B

..

###script

equire 'enumerator'

array=Array.new

File.open('array.text').each{|line| array<<line.split(/\t/)[1]}

#puts array.inspect
array.each_slice(3){|slice|
                   average=(slice[0]+slice[1]+slice[2])/(3.0)
                   puts average
                }

###output from screen

C:/Ruby/self/file6.rb:8: undefined method `/' for "123":String (NoMethodError)
        from c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `each_slice'
        from C:/Ruby/self/file6.rb:7:in `each'
        from C:/Ruby/self/file6.rb:7:in `each_slice'
        from C:/Ruby/self/file6.rb:7

4

You need to tell Ruby to coerce the strings into integers.

array =

File.open('array.text') do |file|
  file.each_line do |line|
    array << line.split[1].to_i
  end
end

array.each_slice(3) do |triplet|
  average = (slice[0]+slice[1]+slice[2])/3.0
  puts average
end

Thank you very much,

Li

···

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