Is there any easy way to convert strings like 3500goat to 3500Goat and goat350rat to Goat350rat?
I am trying to convert the first occurrence of alphabet in an alphanumeric string to uppercase. I was trying the code below using the method sub, but no luck.
stringtomigrate = 3500goat
stringtomigrate.sub!(/\D{0,1}/) do |w|
w.capitalize
This should work:
string.sub(/[a-zA-Z]/) { |s| s.upcase }
or a shorthand:
string.sub(/[a-zA-Z]/, &:upcase)
examples:
'3500goat'.sub(/[a-zA-Z]/, &:upcase)
# => "3500Goat"
'goat350rat'.sub(/[a-zA-Z]/, &:upcase)
# => "Goat350rat"
Try this
1.9.3-p545 :060 > require 'active_support/core_ext'
=> true
1.9.3-p545 :099 > "goat350rat to Goat350rat".sub(/[a-zA-Z]/){ |x| x.titleize}
=> "Goat350rat to Goat350rat"
Related
I'm using Ruby 2.4. How do I write a regular expression in which matches something where the last character is a dash and the preceding character is not a dash or the beginning of the line. So this expression shoudl match
"-"
as shoudl
"ab-"
but this should not
"---"
I tried the below but I'm not matching anything
2.4.0 :012 > word = "abc-"
=> "abc-"
2.4.0 :013 > word =~ /(^|\^\-)\-$/
=> nil
Here is my go at it:
regex = /[^-\A]-\z/
%w(- ab- ---).map { |s| s =~ regex }
=> [nil, 1, nil]
Not 100% sure I got your requirements right, but this does seem to do the trick:
regex = /(^|(?!-).*)-$/
%w(- ab- ---).map { |s| s =~ regex }
#=> [0, 0, nil]
Check it out on Rubular with some test cases.
I want to use regexes to check if a given string is composed of certain substrings.
For example, given the regular expression
> regex = /(?:(foo)|(bar)|(baz))*/
I can determine whether a given string matches the pattern:
> regex === "bazbar"
=> true
> regex === "qux"
=> false
But I want to know how to break the string into substrings. I can almost do this with
> regex.match("barbazfoo").captures
=> ["foo", "bar", "baz"]
But here they appear in the order in which I specified them within the regex. I want to return
["bar", "baz", "foo"]
In the order in which they appeared in the string.
You can use String#scan with a modified regular expression:
regex = /foo|bar|baz/
"barbazfoo".scan(regex)
# => ["bar", "baz", "foo"]
UPDATE according to OP's comment.
If some of the strings I'm using are substrings of the others, you need to order the so that all the substrings go last.
"barfoo".scan(/ba|bar|foo/) # without ordering
# => ["ba", "foo"]
words = ['ba', 'bar', 'foo']
pattern = words.map { |word| Regexp.escape(word) }.sort_by { |x| -x.size }.join('|')
"barfoo".scan(Regexp.new(pattern))
# => ["bar", "foo"]
I have a string like this
a="[\"6000208900\",\"600020890225\",\"600900231930\"]"
#expected result [6000208900,600020890225,600900231930]
I am trying to remove the backslash from the string.
a.gsub!(/^\"|\"?$/, '')
Inside the double quoted string(""), another double quotes must be escaped by \. You can't remove it.
Use puts, you can see it is not there.
a = "[\"6000208902912790\"]"
puts a # => ["6000208902912790"]
Or use JSON
irb(main):001:0> require 'json'
=> true
irb(main):002:0> a = "[\"6000208902912790\"]"
=> "[\"6000208902912790\"]"
irb(main):003:0> b = JSON.parse a
=> ["6000208902912790"]
irb(main):004:0> b
=> ["6000208902912790"]
irb(main):005:0> b.to_s
=> "[\"6000208902912790\"]"
update (as per the last edit of OP)
irb(main):002:0> a = "[\"6000208900\",\"600020890225\",\"600900231930\"]"
=> "[\"6000208900\",\"600020890225\",\"600900231930\"]"
irb(main):006:0> a.scan(/\d+/).map(&:to_i)
=> [6000208900, 600020890225, 600900231930]
irb(main):007:0>
The code a.gsub!(/^\"|\"?$/, '') can't remove the double quote characters because they are not at the beginning and the end of the string. To get what you want try this:
a.gsub(/((?<=^\[)")|("(?=\]$))/, '')
try this:
=> a = "[\"6000208902912790\"]"
=> a.chars.select{ |x| x =~ %r|\d| }.join
=> "6000208902912790"
=> [a.chars.select { |x| x =~ %r|\d| }.join]
=> ["6000208902912790"] # <= array with string
=> [a.chars.select { |x| x =~ %r|\d| }.join].to_s
=> "[\"6000208902912790\"]" # <= come back :)
a="["6000208902912790"]" will return `unexpected tINTEGER`error;
so a="[\"6000208902912790\"]"is used with \ character for double quotes.
As a solution you should try to remove double quotes that will solve the problem.
Do this
a.gsub!(/"/, '')
I would like to strip all non-digit characters from a string.
/\D/ is a non-digit character ([^0-9]):
irb(main):010:0> s = "(123) 456-7890"
=> "(123) 456-7890"
irb(main):011:0> s.sub( /\D*/, '' )
=> "123) 456-7890"
Do as below using String#tr or String#gsub:
s.gsub(/[[:punct:]]|[[:space:]]/ ,'')
# => "1234567890"
s.tr('^0-9','') # even more faster
# => "1234567890"
sub replaces once. gsub replaces all.
Use gsub instead:
s.gsub( /\D/, '' )
I understand how to check for a pattern in string with regexp in ruby. What I am confused about is how to save the pattern found in string as a separate string.
I thought I could say something like:
if string =~ /regexp/
pattern = string.grep(/regexp/)
and then I could be on with my life. However, this isn't working as expected and is returning the entire original string. Any advice?
You're looking for string.match() in ruby.
irb(main):003:0> a
=> "hi"
irb(main):004:0> a=~/(hi)/
=> 0
irb(main):005:0> a.match(/hi/)
=> #<MatchData:0x5b6e8>
irb(main):006:0> a.match(/hi/)[0]
=> "hi"
irb(main):007:0> a.match(/h(i)/)[1]
=> "i"
irb(main):008:0>
But also for working with what you just matched in the if condition you can use $& $1..$9 and $~ as such:
irb(main):009:0> if a =~ /h(i)/
irb(main):010:1> puts("%s %s %s %s"%[$&,$1,$~[0],$~[1]])
irb(main):011:1> end
hi i hi i
=> nil
irb(main):012:0>
You can also use the special variables $& and $1-$n, like so:
if "regex" =~ /reg(ex)/
puts $&
puts $1
end
Outputs:
regex
ex
$~ also contains the MatchData object. See also: http://www.regular-expressions.info/ruby.html.
I prefer some shortcuts like:
email = "Khaled Al Habache <khellls#gmail.com>"
email[/<(.*?)>/, 1] # => "khellls#gmail.com"