I would like to know what it does:
File.open(filename,"r").each_file do |line|
if (!line.strip.empty? and !line.starts_with?(" "))
....
.....
end
end
Especially what isstrip? Thanks for your time!
Strip removes all the leading and trailing whitespace chars from a string. In essense the code you pasted checks if the sting contains anything apart from whitespaces AND the first symbol is not a space.
Related
I'm struggling with a script to target specific XML files in a directory and rename them as copies with a different name.
I put in the puts statements for debugging, and, from what I can tell, everything looks OK until the FileUtils.cp line. I tried this with simpler text and it worked, but my overly complicated cp(file, file.gsub()) seems to be causing problems that I can't figure out.
def piano_treatment(cats)
FileUtils.chdir('12Piano')
src = Dir.glob('*.xml')
src.each do |file|
puts file
cats.each do |text|
puts text
if file =~ /#{text}--\d\d/
puts "Match Found!!"
puts FileUtils.pwd
FileUtils.cp(file, file.gsub!(/#{text}--\d\d/, "#{text}--\d\dBass "))
end
end
end
end
piano_treatment(cats)
I get the following output in Terminal:
12Piano--05Free Stuff--11Test.xml
05Free Stuff
Match Found!!
/Users/mbp/Desktop/Sibelius_Export/12Piano
cp 12Piano--05Free Stuff--ddBass Test.xml 12Piano--05Free Stuff--ddBass Test.xml
/Users/mbp/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/fileutils.rb:1551:in `stat': No such file or directory - 12Piano--05Free Stuff--ddBass Test.xml (Errno::ENOENT)
Why is \d\d showing up as "dd" when it should actually be numbers? Is this a single vs. double quote issue? Both yield errors.
Any suggestions are appreciated. Thanks.
EDIT One additional change was needed to this code. The FileUtils.chdir('12Piano') would change the directory for the first iteration of the loop, but it would revert to the source directory after that. Instead I did this:
def piano_treatment(cats)
src = Dir.glob('12Piano/*.xml')
which sets the match path for the whole method.
Your replacement string is not a regex, so \d has no special meaning, but is just a literal string. You need to specify a group in your regex, and then you can use the captured group in your replacement string:
FileUtils.cp(file, file.gsub(/#{text}--(\d\d)/, "#{text}--\\1Bass "))
The parenthesis in the regex form the group, which can be used (by number) in the replacement string: \1 for the first group, \2 for the second, etc. \0 refers to the entire regex match.
Update
Replaced gsub!() with gsub() and escaped the backslash in the replacement string (to treat \1 as the capture group, not a literal character... Doh!).
Trying to change this:
"The basketball-player is great! (Kobe Bryant)"
into this:
"the basketball player is great kobe bryant"
Want to downcase and remove all punctuation but leave spaces...
Tried string.downcase.gsub(/[^a-z ]/, '') but it removes the spaces
You can simply add \s (whitespace)
string.downcase.gsub(/[^a-z0-9\s]/i, '')
If you want to catch non-latin characters, too:
str = "The basketball-player is great! (Kobe Bryant) (ひらがな)"
str.downcase.gsub(/[^[:word:]\s]/, '')
#=> "the basketballplayer is great kobe bryant ひらがな"
Some fine solutions, but simplest is usually best:
string.downcase.gsub /\W+/, ' '
All the other answers strip out numbers as well. That works for the example given but doesn't really answer the question which is how to strip out non-alphanumeric.
string.downcase.gsub(/[^\w\s]/, '')
Note this will not strip out underscores. If you need that then:
string.downcase.gsub(/[^a-zA-Z\s\d]/, '')
a.downcase.gsub(/[^a-z ]/, "")
Note the whitespace I have added after a-z.
Also if you want to replace all whitespaces(not only space use \s as proposed by gmalette).
All the previous answers make basketball-player into basketballplayer or remove numbers entirely, which is not exactly what is required.
The following code does exactly what you asked:
text.downcase
.gsub(/[^[:word:]\s]/, ' ') # Replace sequences of non-alphanumerical chars by a single space
Hope this helps someone!
I need to remove newlines at the beginning and at the end of a string in ruby (some sort of trimming).
But JUST at the beginning and the end... The new lines located in the middle of the string must remain untouched.
Thank you!
You can use String#strip method.
"\tgoodbye\r\n".strip #=> "goodbye"
String.strip will remove all extra whitespace from the front and back, leaving innards alone.
http://ruby-doc.org/core/classes/String.html#M001189
This should do it:
string.lstrip!.rstrip!
If your intent is to strip just whitespace then the strip method should work...but if your trying to target new lines specifically then maybe try this:
"\r\na b c d\r\ne f g\r\n".gsub(/^\r\n/, "").gsub(/\r\n$/, "")
=> "a b c d\r\ne f g"
the gsub method will use regular expression to target the beginning ^ and end $ locations for replacement with "".
NOTE: Here I made the assumption that your newline is \r\n. This may not be platform independent.
The platform independent version of NPatel's answer is:
"\nabc\ndef\n".gsub(/^#{$/}/, "").gsub(/#{$/}$/, "")
I have a piece of text that resembled the following:
==EXCLUDE
#lots of lines of text
==EXCLUDE
#this is what I actually want
And so I was trying to remove the unwanted bit by doing:
str.gsub!(/==EX.*?==EXCLUDE/, '')
However, its not working. When I tried to remove the \n chars first, it worked like a dream. The issue is that I can't actually remove the \n characters. How can I do a substitution like this while leaving newlines in place?
By default, the . does not match line break chars. If you enable the m modifier in Ruby (in other languages, this is the s modifier) it should work:
str.gsub!(/==EX.*?==EXCLUDE/m, '')
Here's a live demo on Rubular: http://rubular.com/r/YxLSB1Iq95
Try str.gsub!(/==EX.*?==EXCLUDE/m, '')
That should make it span new lines.
I'm trying to learn RegEx in Ruby, based on what I'm reading in "The Rails Way". But, even this simple example has me stumped. I can't tell if it is a typo or not:
text.gsub(/\s/, "-").gsub([^\W-], '').downcase
It seems to me that this would replace all spaces with -, then anywhere a string starts with a non letter or number followed by a dash, replace that with ''. But, using irb, it fails first on ^:
syntax error, unexpected '^', expecting ']'
If I take out the ^, it fails again on the W.
>> text = "I love spaces"
=> "I love spaces"
>> text.gsub(/\s/, "-").gsub(/[^\W-]/, '').downcase
=> "--"
Missing //
Although this makes a little more sense :-)
>> text.gsub(/\s/, "-").gsub(/([^\W-])/, '\1').downcase
=> "i-love-spaces"
And this is probably what is meant
>> text.gsub(/\s/, "-").gsub(/[^\w-]/, '').downcase
=> "i-love-spaces"
\W means "not a word"
\w means "a word"
The // generate a regexp object
/[^\W-]/.class
=> Regexp
Step 1: Add this to your bookmarks. Whenever I need to look up regexes, it's my first stop
Step 2: Let's walk through your code
text.gsub(/\s/, "-")
You're calling the gsub function, and giving it 2 parameters.
The first parameter is /\s/, which is ruby for "create a new regexp containing \s (the // are like special "" for regexes).
The second parameter is the string "-".
This will therefore replace all whitespace characters with hyphens. So far, so good.
.gsub([^\W-], '').downcase
Next you call gsub again, passing it 2 parameters.
The first parameter is [^\W-]. Because we didn't quote it in forward-slashes, ruby will literally try run that code. [] creates an array, then it tries to put ^\W- into the array, which is not valid code, so it breaks.
Changing it to /[^\W-]/ gives us a valid regex.
Looking at the regex, the [] says 'match any character in this group. The group contains \W (which means non-word character) and -, so the regex should match any non-word character, or any hyphen.
As the second thing you pass to gsub is an empty string, it should end up replacing all the non-word characters and hyphens with empty string (thereby stripping them out )
.downcase
Which just converts the string to lower case.
Hope this helps :-)
You forgot the slashes. It should be /[^\W-]/
Well, .gsub(/[^\W-]/,'') says replace anything that's a not word nor a - for nothing.
You probably want
>> text.gsub(/\s/, "-").gsub(/[^\w-]/, '').downcase
=> "i-love-spaces"
Lower case \w (\W is just the opposite)
The slashes are to say that the thing between them is a regular expression, much like quotes say the thing between them is a string.