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comp.lang.ruby

How to remove empty space in a string and others

Li Chen

10/9/2006 1:14:00 PM

Hi all,

1) I read lines from a file and put them into one string. There are many
empty sapces within the string. Which method is used to remove the
spaces? I try gsub!("\s",'') but it doesn't work. Any help will be
appreciated.

2) I read each line from a file and split each of them into several
fields/segments. Then I need to populate an array with one field only
from each line. How do I do that? I know do these in Perl but have no
idea using Ruby.

3) How do I search help or some methods/predifined variables from ruby
command prompt? Is it possible to do that? Right now the only thing I
can do is to open the folder containing the manual and read them in IE
browser. Is this the Ruby way?

Thanks in advance,

Li

--
Posted via http://www.ruby-....
4 Answers

Morton Goldberg

10/9/2006 1:53:00 PM

0

On Oct 9, 2006, at 9:13 AM, Li Chen wrote:

> Hi all,
>
> 1) I read lines from a file and put them into one string. There are
> many
> empty sapces within the string. Which method is used to remove the
> spaces? I try gsub!("\s",'') but it doesn't work. Any help will be
> appreciated.

Try gsub(/\s/, '')

> 2) I read each line from a file and split each of them into several
> fields/segments. Then I need to populate an array with one field only
> from each line. How do I do that? I know do these in Perl but have no
> idea using Ruby.

Would need more information about your code to answer this.

> 3) How do I search help or some methods/predifined variables from ruby
> command prompt? Is it possible to do that? Right now the only thing I
> can do is to open the folder containing the manual and read them
> in IE
> browser. Is this the Ruby way?

There's nothing wrong with your way, but there are many other ways to
get help while coding. Here are two you might consider:

1. visit and download from

http://ruby.cenophobie.com/rub...

The Ruby Cheatsheet is especially good for looking up predefined
variables.

2. Open another terminal window and use ri to get help on classes and
methods. For example:

ri gsub

Regards, Morton

Li Chen

10/9/2006 4:41:00 PM

0


>> 2) I read each line from a file and split each of them into several
>> fields/segments. Then I need to populate an array with one field only
>> from each line. How do I do that? I know do these in Perl but have no
>> idea using Ruby.
>
> Would need more information about your code to answer this.

I have a file called array.txt with many lines and each line is a record
containing different fields separated by \t. What I like to do is read
the file line by line, split each line into elements, and push the
element [1] from each line into a new array.

# array.txt

A B C
1 2 3
X Y Z
...

expected output in new array
[B,2,Y,...]

Thanks,

Li

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Posted via http://www.ruby-....

Jeff Wood

10/9/2006 4:48:00 PM

0

Li Chen wrote:
>>> 2) I read each line from a file and split each of them into several
>>> fields/segments. Then I need to populate an array with one field only
>>> from each line. How do I do that? I know do these in Perl but have no
>>> idea using Ruby.
>>>
>> Would need more information about your code to answer this.
>>
>
> I have a file called array.txt with many lines and each line is a record
> containing different fields separated by \t. What I like to do is read
> the file line by line, split each line into elements, and push the
> element [1] from each line into a new array.
>
> # array.txt
>
> A B C
> 1 2 3
> X Y Z
> ...
>
> expected output in new array
> [B,2,Y,...]
>
> Thanks,
>
> Li
>
>
output = []
File.open( "array.txt" ) { |file| file.readlines { |curr_line| output
<< curr_line.split( /\t/ )[1] } }

# just to show the result
require 'pp'
pp output

Li Chen

10/9/2006 5:54:00 PM

0


>>
> output = []
> File.open( "array.txt" ) { |file| file.readlines { |curr_line| output
> << curr_line.split( /\t/ )[1] } }
>
> # just to show the result
> require 'pp'
> pp output

I need more information about file reading. Which chapter in the
Programming Ruby talks about this stuff?

Thanks,

Li

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