Need help about Ruby with text file

Ruby
1

Hi, everybody

This is my first time get into this forum.
I would like to know that is it a forum for us to discuss about
everythings in Ruby, please?
If so,
1)I would like to know that how can I delete or remove a line in a text
file, please?
2)How can I read some letter in a line, please?
e.g. a text file like this:-

aabbcc
ddeeff
gghhii
jjkkll

1)I want to delete ddeeff become like this:-
aabbcc
gghhii
jjkkll

2)I get the result like :-
hh

Thanks
Regards
Oscar

2

Oscar L. wrote:

aabbcc
ddeeff
gghhii
jjkkll

1)I want to delete ddeeff become like this:-
aabbcc
gghhii
jjkkll

#!/usr/bin/ruby

data=<<EOF
aabbcc
ddeeff
gghhii
jjkkll
EOF

puts “Before:”,data

data.sub!(/ddeeff\n/,"")

puts “\nAfter:”,data

Output:

Before:
aabbcc
ddeeff
gghhii
jjkkll

After:
aabbcc
gghhii
jjkkll

2)I get the result like :-
hh

Please explain the circumstances under which you want to get this
result.

3

Dont do his homework for him :slight_smile:

4

Paul L. wrote:

2)How can I read some letter in a line, please?
jjkkll
EOF

2)I get the result like :-
hh

Please explain the circumstances under which you want to get this result.

He said the text is “in a file”
Cheers

5

Paul L. wrote:

Mike D. wrote:

/ …

2)I get the result like :-
hh

Please explain the circumstances under which you want to get this result.

He said the text is “in a file”

I generally don’t require newbies to create and then read a file for
demonstration purposes. I prefer my examples to run exactly as posted.
This
avoids the otherwise inevitable “I tried it and it didn’t work!”"
replies.

What this means is the OP needs to explain the circumstances under which
he
wants two “h” character in a row, clearly and unambiguously. Before,
after,
and in between.

And now, on re-reading his first post, I can’t tell whether he got that
result and didn’t want it, or didn’t get it and wanted it. Or … got it
and wanted it, and thought he would mention it in passing.

Hi,Paul L.
Thanks for your reply!

aabbcc
ddeeff
gghhii
jjkkll

2)I get the result like :-
hh

  • What I would like to do is :-
  1. go through each line from the begin
  2. compare “hh” each letter on each line
  3. found the line number of “gghhii”
  4. extract “hh” of it.

Thanks!
Oscar

6

Oscar L. wrote:

/ …

jjkkll

2)I get the result like :-
hh

  • What I would like to do is :-
  1. go through each line from the begin
  2. compare “hh” each letter on each line
  3. found the line number of “gghhii”
  4. extract “hh” of it.

Please provide an example. I think you don’t literally mean you want
‘hh’
specifically, but these are meant to stand in for the actual characters
you
want. Yes? Otherwise this would work:

#!/usr/bin/ruby

data = File.read(“example.txt”)

n = 0

data.each do |line|
test = line.sub(/…(…)…/,"\1")
print “#{n}: #{test}\n” if test =~ /hh/
n += 1
end

Example file contains:

aabbcc
ddeeff
gghhii
jjkkll

Output:

2: hh

Conclusion? You simply must explain what you want, clearly enough that
it
can be turned into code.

7

Mike D. wrote:

/ …

2)I get the result like :-
hh

Please explain the circumstances under which you want to get this result.

He said the text is “in a file”

I generally don’t require newbies to create and then read a file for
demonstration purposes. I prefer my examples to run exactly as posted.
This
avoids the otherwise inevitable “I tried it and it didn’t work!”"
replies.

What this means is the OP needs to explain the circumstances under which
he
wants two “h” character in a row, clearly and unambiguously. Before,
after,
and in between.

And now, on re-reading his first post, I can’t tell whether he got that
result and didn’t want it, or didn’t get it and wanted it. Or … got it
and wanted it, and thought he would mention it in passing.

8

Example file contains:

aabbcc
ddeeff
gghhii
jjkkll

Output:

2: hh

Thanks a lots!
Ruby script really is a great script!
By the way, may I know that is there any function like e.g. left(line,
3), right(line, 2) and mid(line, 1, 4) to extract letter from a line,
please?
e.g.
mid(gghhii,3,2) return hh
left(gghhii,3) return ggh
right(gghhii,3) return hii

Thanks!
Oscar

9

On Sat, 16 Sep 2006, Oscar L. wrote:

By the way, may I know that is there any function like e.g. left(line,
3), right(line, 2) and mid(line, 1, 4) to extract letter from a line,
please?
e.g.
mid(gghhii,3,2) return hh
left(gghhii,3) return ggh
right(gghhii,3) return hii

ri String#[] gives (for ruby-1.8.5):

-------------------------------------------------------------- String#[]
str[fixnum] => fixnum or nil
str[fixnum, fixnum] => new_str or nil
str[range] => new_str or nil
str[regexp] => new_str or nil
str[regexp, fixnum] => new_str or nil
str[other_str] => new_str or nil
str.slice(fixnum) => fixnum or nil
str.slice(fixnum, fixnum) => new_str or nil
str.slice(range) => new_str or nil
str.slice(regexp) => new_str or nil
str.slice(regexp, fixnum) => new_str or nil
str.slice(other_str) => new_str or nil

 Element Reference---If passed a single +Fixnum+, returns the code
 of the character at that position. If passed two +Fixnum+ objects,
 returns a substring starting at the offset given by the first, and
 a length given by the second. If given a range, a substring
 containing characters at offsets given by the range is returned. In
 all three cases, if an offset is negative, it is counted from the
 end of _str_. Returns +nil+ if the initial offset falls outside the
 string, the length is negative, or the beginning of the range is
 greater than the end.

 If a +Regexp+ is supplied, the matching portion of _str_ is
 returned. If a numeric parameter follows the regular expression,
 that component of the +MatchData+ is returned instead. If a
 +String+ is given, that string is returned if it occurs in _str_.
 In both cases, +nil+ is returned if there is no match.

    a = "hello there"
    a[1]                   #=> 101
    a[1,3]                 #=> "ell"
    a[1..3]                #=> "ell"
    a[-3,2]                #=> "er"
    a[-4..-2]              #=> "her"
    a[12..-1]              #=> nil
    a[-2..-4]              #=> ""
    a[/[aeiou](.)\1/]      #=> "ell"
    a[/[aeiou](.)\1/, 0]   #=> "ell"
    a[/[aeiou](.)\1/, 1]   #=> "l"
    a[/[aeiou](.)\1/, 2]   #=> nil
    a["lo"]                #=> "lo"
    a["bye"]               #=> nil

Take the time to explore ri, which you should have on your system.
It is very good.

Thanks!
Oscar

    Hugh
10

Oscar L. wrote:

/ …

Thanks a lots!
Ruby script really is a great script!
By the way, may I know that is there any function like e.g. left(line,
3), right(line, 2) and mid(line, 1, 4) to extract letter from a line,
please?
e.g.
mid(gghhii,3,2) return hh
left(gghhii,3) return ggh
right(gghhii,3) return hii

#!/usr/bin/ruby

s = “gghhii”

puts s
puts s[0,2]
puts s[2,2]
puts s[-2,2]

Output:

gghhii
gg
hh
ii

11

Hai,
It is neat and simple(compare to others programing)! Very easy to
understand!

Thanks!

Regards
Oscar

12

Oscar L. wrote:

Hai,
It is neat and simple(compare to others programing)! Very easy to
understand!

Thanks!

You are welcome. I sincerely hope you will also read Hugh S.'s post.
It
offers more general guidance. IOW I gave you a fish, but he tries to
teach
you how to fish.