Hello,
I have been using awk for some text handling.
Now I'm beginning Ruby (really newbie) and want to find a way in ruby
to do this with awk:
awk '{if ($4~/something/) {i+=1}} END {print i}' file.txt
That means if a line's 4th field match "something" then increase the
counter by 1.
How to write the corresponding ruby code?
Thanks in advance.
What is a 'field'? Whitespace delimited?
On Nov 21, 7:09 pm, Ruby Newbee <rubynew...@gmail.com> wrote:
awk '{if ($4~/something/) {i+=1}} END {print i}' file.txt
That means if a line's 4th field match "something" then increase the
counter by 1.
How to write the corresponding ruby code?
Yes, thanks.
2009/11/22 Phrogz <phrogz@mac.com>:
On Nov 21, 7:09 pm, Ruby Newbee <rubynew...@gmail.com> wrote:
awk '{if ($4~/something/) {i+=1}} END {print i}' file.txt
That means if a line's 4th field match "something" then increase the
counter by 1.
How to write the corresponding ruby code?What is a 'field'? Whitespace delimited?
Here are two ways:
# Don't read the whole file into memory, but do it one line at a time
i = 0
file = File.open( "foo.txt" )
file.each_line do |line|
pieces = line.split( /\s+/ )
i += 1 if pieces[ 3 ] =~ /something/
end
# Just read the whole file at once, assuming it's small enough,
# and create an array of the fourth column's
col = File.read("foo.txt").scan(/.+/).map{ |line| line.scan(/\S+/)
[3] }
i = col.count{ |val| val =~ /something/ }
On Nov 21, 8:00 pm, Ruby Newbee <rubynew...@gmail.com> wrote:
2009/11/22 Phrogz <phr...@mac.com>:
> On Nov 21, 7:09 pm, Ruby Newbee <rubynew...@gmail.com> wrote:
>> awk '{if ($4~/something/) {i+=1}} END {print i}' file.txt
>> That means if a line's 4th field match "something" then increase the
>> counter by 1.
>> How to write the corresponding ruby code?
> What is a 'field'? Whitespace delimited?
Yes, thanks.
I like that, thank you!
2009/11/22 Phrogz <phrogz@mac.com>:
# Don't read the whole file into memory, but do it one line at a time
i = 0
file = File.open( "foo.txt" )
file.each_line do |line|
pieces = line.split( /\s+/ )
i += 1 if pieces[ 3 ] =~ /something/
end
# Don't read the whole file into memory, but do it one line at a time
i = 0
file = File.open( "foo.txt" )
file.each_line do |line|
pieces = line.split( /\s+/ )
i += 1 if pieces[ 3 ] =~ /something/
end
I like that, thank you!
The code above does not close the file handle properly. Also if can be done shorter:
File.foreach "file.txt" do |line|
...
end
You can even use Ruby like awk which seems to be rarely done - but it's possible.
awk '{if ($4~/something/) {i+=1}} END {print i}' file.txt
Can be done like
ruby -nae 'BEGIN {$i=0}; $i+=1 if /something/ =~ $F[3]; END {puts $i}' file.txt
ruby -nae 'BEGIN {$i=0}; /something/ =~ $F[3] and $i+=1; END {puts $i}' file.txt
For a script, I'd probably do something similar to what Phrogz suggested but with the difference that I'd use ARGF. That way you fetch file names from the command line and do not need to change the script if the file name changes:
i = 0
ARGF.each do |line|
bit = line.split(/\s+/)[3]
i += 1 if /something/ =~ bit
end
puts i
Or, do the matching in one step which seems more efficient
i = 0
ARGF.each do |line|
i += 1 if /^\s*(?:\S+\s+){3}something/ =~ line
end
puts i
There are about 2,843 million other ways to do it in Ruby.
Kind regards
robert
On 22.11.2009 10:12, Ruby Newbee wrote:
2009/11/22 Phrogz <phrogz@mac.com>:
--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/
oops this is the same way as Perl's.
I may adjust one point:
should be:
$F[3] =~ /something/;
not:
/something/ =~ $F[3];
After that replace "ruby" to "perl" on above commands and that will be
working too.
Thanks~
2009/11/22 Robert Klemme <shortcutter@googlemail.com>:
ruby -nae 'BEGIN {$i=0}; $i+=1 if /something/ =~ $F[3]; END {puts $i}'
file.txt
ruby -nae 'BEGIN {$i=0}; /something/ =~ $F[3] and $i+=1; END {puts $i}'
file.txt
ruby -nae 'BEGIN {$i=0}; $i+=1 if /something/ =~ $F[3]; END {puts $i}'
file.txt
ruby -nae 'BEGIN {$i=0}; /something/ =~ $F[3] and $i+=1; END {puts $i}'
file.txtoops this is the same way as Perl's.
I may adjust one point:
should be:
$F[3] =~ /something/;not:
/something/ =~ $F[3];
Why?
After that replace "ruby" to "perl" on above commands and that will be
working too.
Ah, you want a single program to work both for Perl and Ruby. Thanks
for sharing!
I usually prefer to have the regular expression as the first argument
to =~ because for me that seems more natural (the regexp is doing the
matching) and IIRC it is a tad faster (but really only a tad).
Kind regards
robert
2009/11/23 Ruby Newbee <rubynewbee@gmail.com>:
2009/11/22 Robert Klemme <shortcutter@googlemail.com>:
--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/