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Re: newbie questions on processing numerical data from text files

Axel Etzold

6/29/2007 1:32:00 PM

Dear Baptiste,

welcome to Ruby!

> Here is my practical problem:
>
> - I open a text file,

(... which already exists):

interesting_text=IO.readlines(file_name)

gives you an Array, with the lines as entries



>locate a line according to some keyword


interesting_text.delete_if{|line| /(r|R)uby/.match==nil}

removes all lines that don't contain the string Ruby or ruby,

> or line number,


interesting_text[line_number] # (start counting at 0)



> and change a value
old_value=1.2
new_value=2.4

interesting_text.sub!(value.to_s,new_value.to_s)

> - I run a fortran program

result=`...` where ... is the system command you use to start
your fortran program,


> - I read a text file (output of this program), extract several
> numerical values

You can do the reading with IO.readlines, the extraction with a
Regexp,

> and export them in a two column text file

and this via

f=File.new("my_result_file.txt","w")
f.puts formatted_text
f.close


> Here is the content of "sampleTextFile.dat":
>
> > this is a meaningless line
> > another one
> >
> > maybe this line acts as a keyword for the following data
> >

I don't know how to interpret the values in brackets in the
following line:

> > 1 3.1 (415, 19e-12)

If you read the file in via IO.readlines, it's a String element
of an Array, say line="1 3.1 (415, 19e-12)"
so you could do:

numbers=line.gsub(/[\(,\)]/,'').split <= removes brackets an gives
a four element Array (of Strings), which you can turn ito numbers via
eval

number_array=line.gsub(/[\(,\)]/,'').split.map{|x| eval(x)}

Some other approach might be to assign variable names to each element
in a line

vars_names=['a','b','c','d']
array_of_hashes=[]
lines.each{|line|
vals_line=line.gsub(/[\(,\)]/,'').split.map{|x| eval(x)}
tmp={}
vars_names.each_with_index{|var_name,index|
tmp.store(var_name,vals_line[index])
}
array_of_hashes<<tmp
}

will give something like:

[{"a"=>1,"b"=>3.1,"c"=>415,"d"=>19e-12},...]



Best regards,

Axel
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3 Answers

Axel Etzold

6/29/2007 2:02:00 PM

0

> How i create array under ruby?
> for example need create a vector type array

Like this:

a=[]
a=Array.new
a=[1,2,3]
a=[1,"a",9.0]

You can include elements from all sorts of
classes into an Array.

Best regards,

Axel


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Axel Etzold

6/29/2007 6:59:00 PM

0

> > interesting_text.delete_if{|line| /(r|R)uby/.match==nil}
> >
> > removes all lines that don't contain the string Ruby or ruby,
>
> for some reason this doesn't work for me. I get an error message:
> ArgumentError: wrong number of arguments (0 for 1)
>
>
> if i replace this argument with something based on line numbers
> rather than regexp, it's fine. Is the Regexp wrong?

You're right. The line should read:

interesting_text.delete_if{|line| /(r|R)uby/.match(line)==nil}

>
>
> >
> >> and change a value
> > old_value=1.2
> > new_value=2.4
> >
> > interesting_text.sub!(old_value.to_s,new_value.to_s)
> >
>
> I can't get that to work either :
> NoMethodError: private method `sub!' called for #<Array:0x7d180>
>
.. and again .. sub, gsub, sub!,gsub! are for Strings ... so
either:

interesting_text=IO.readlines(file_name).to_s
interesting_text.sub!(old_value.to_s,new_value.to_s)

or , if, each line is to be processed separately,

interesting_text=IO.readlines(file_name)

new_text=interesting_text.each{|line|
line.sub(old_value.to_s,new_value.to_s)}

Sorry for the confusion.

Best regards,

Axel
>
>
> >
> >
> > Best regards,
> >
> > Axel
>
>
> The rest works fine, thanks again!
>
> baptiste
>
>

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baptiste Auguié

6/29/2007 8:33:00 PM

0

awesome, it works! It's all starting to make some sense now.

Thanks!

baptiste

On 29 Jun 2007, at 19:58, Axel Etzold wrote:

>>> interesting_text.delete_if{|line| /(r|R)uby/.match==nil}
>>>
>>> removes all lines that don't contain the string Ruby or ruby,
>>
>> for some reason this doesn't work for me. I get an error message:
>> ArgumentError: wrong number of arguments (0 for 1)
>>
>>
>> if i replace this argument with something based on line numbers
>> rather than regexp, it's fine. Is the Regexp wrong?
>
> You're right. The line should read:
>
> interesting_text.delete_if{|line| /(r|R)uby/.match(line)==nil}
>
>>
>>
>>>
>>>> and change a value
>>> old_value=1.2
>>> new_value=2.4
>>>
>>> interesting_text.sub!(old_value.to_s,new_value.to_s)
>>>
>>
>> I can't get that to work either :
>> NoMethodError: private method `sub!' called for #<Array:0x7d180>
>>
> .. and again .. sub, gsub, sub!,gsub! are for Strings ... so
> either:
>
> interesting_text=IO.readlines(file_name).to_s
> interesting_text.sub!(old_value.to_s,new_value.to_s)
>
> or , if, each line is to be processed separately,
>
> interesting_text=IO.readlines(file_name)
>
> new_text=interesting_text.each{|line|
> line.sub(old_value.to_s,new_value.to_s)}
>
> Sorry for the confusion.
>
> Best regards,
>
> Axel
>>
>>
>>>
>>>
>>> Best regards,
>>>
>>> Axel
>>
>>
>> The rest works fine, thanks again!
>>
>> baptiste
>>
>>
>
> --
> Der GMX SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen!
> Ideal für Modem und ISDN: http://www.gmx.net/de/go/s...
>