regexp issue on parsing from file

[Alpha Blue]

Hi guys,

I've always had trouble with regexp and matching. I'm trying to figure
out how to parse a very lengthy file that contains information similar
to below:

["Name"] = {
80, -- [1]
"Company", -- [2]
"2009-08-14", -- [3]
},
["NameTwo"] = {
24, -- [1]
"Company Two", -- [2]
"2009-08-14", -- [3]
},

The only information I am interested in is the following:

["Name"]
["NameTwo"]

And to further break it down, I'm only interested out of that:

Name
NameTwo

The large file contains roughly 10,000 - 20,000 lines of the similar
data below.

I just want to do open the file, parse out the information as it finds
it, and place it into an array for writing to another file which
contains the proper syntax.

Any help would be appreciative on how to match the specific line to get
that piece of data, and how to ignore the rest of the lines it finds
that contains no matches.

Many thanks.

 

[Alpha Blue]

Okay I'm getting closer..

counter = 1
name_re = /(.*)\[(.*)\{/
File.open("census.lua", "r") do |infile|
while (line = infile.gets)
if (line =~ name_re)
puts "#{counter}: #{line}"
counter = counter + 1
end
end
end

This gets me the data from the one line:

["Name"] = {
["NameTwo"] = {

 

[Ben Giddings]

["Name"] = {
80, -- [1]
"Company", -- [2]
"2009-08-14", -- [3]
},
["NameTwo"] = {
24, -- [1]
"Company Two", -- [2]
"2009-08-14", -- [3]
},

Try something like this:

File.foreach("filename") do |line|
if md = /^\["(\w+)"\]/.match(line)
puts md[1]
end
end

 

[Alpha Blue]

Hi Ben,

this actually did the trick:

counter = 1
name_re = /(.*)\[(.*)\{/
File.open("census.lua", "r") do |infile|
while (line = infile.gets)
if (line =~ name_re)
s_line = line.strip
c_line = s_line.size
left = c_line
right = c_line - 7
puts "#{counter}: #{s_line.slice!(2..right)}"
counter = counter + 1
end
end
end

 

[Alpha Blue]

Correction

counter = 1
name_re = /(.*)\[(.*)\{/
File.open("census.lua", "r") do |infile|
while (line = infile.gets)
if (line =~ name_re)
s_line = line.strip
c_line = s_line.size
right = c_line - 7
puts "#{counter}: #{s_line.slice!(2..right)}"
counter = counter + 1
end
end
end

 

[7stud --]

Correction

counter = 1
name_re = /(.*)\[(.*)\{/
File.open("census.lua", "r") do |infile|
while (line = infile.gets)
if (line =~ name_re)
s_line = line.strip
c_line = s_line.size
right = c_line - 7
puts "#{counter}: #{s_line.slice!(2..right)}"
counter = counter + 1
end
end
end

Ben's regex is better, and once you've done the matching, if your regex
has a group around the desired information, you can retrieve the desired
information--there is no need to slice and dice the string to extract
the information:

count = 1

IO.foreach("data.txt") do |line|
if md = /^\["(\w+?)"\]/.match(line)
puts "#{count}: #{md[1]}"
count += 1
end
end

--output:--
1: Name
2: NameTwo

The term:

/^\["(\w+)"\]/.match(line)

returns a MatchData object if there is a match. Otherwise, it returns
nil. That result is assigned to the variable md. A MatchData object
will evaluate to true. So if a MatchData object is returned, i.e. there
is a match, the if condition will evaluate to true, and the body of the
if statement will execute. Inside the if statement, you can ask the
MatchData object for the match for the group in your regex. md[0] is
the whole match, md[1] is the match for group 1, md[2], is the match for
group 2, etc.

The regexp says to look for the start of the string(^), then an opening
bracket, then a double quote mark, then any character [a-zA-Z0-9] one or
more times(+), then a quote mark, then a closing bracket.

 

[7stud --]

Ben's regex is better, and once you've done the matching, if your regex
has a group around the desired information, you can retrieve the desired
information--there is no need to slice and dice the string to extract
the information:

On the other hand, if you would rather avoid regex's altogether and
stick to string slicing and dicing, you could do this:

count = 1

IO.foreach("data.txt") do |line|
if line[0, 1] == "[":
first_piece = line.split(" ", 2)[0]
puts "#{count}: #{first_piece[2...-2]}"
count += 1
end
end



--output:--
1: Name
2: NameTwo

 

[7stud --]

count = 1

IO.foreach("data.txt") do |line|
if line[0, 1] == "[":
first_piece = line.split(" ", 2)[0]
puts "#{count}: #{first_piece[2...-2]}"

Or replace those 2 lines with:
puts %Q{#{count}: #{ line.split('"')[1] }}

I'm not a big fan of cramming stuff into one liners, but I like this:

line.split('"')[1]

 

[Alpha Blue]

Thanks for the information fellas. It's good to know of multiple ways
for accomplishing the same task and which one is better.

 

[Ben Giddings]

File.open("census.lua", "r") do |infile|
while (line = infile.gets)

BTW, you might want to look at the more rubyish ways of iterating over
the lines of a file. The way you do it works, but is more complex
than it needs to be.

Ben