Why would you ever use %w[] considering arrays in Rails are type-agnostic?
This is the most efficient way to define array of strings, because you don't have to use quotes and commas.
%w(abc def xyz)
Instead of
['abc', 'def', 'xyz']
Duplicate question of
http://stackoverflow.com/questions/1274675/what-does-warray-mean
http://stackoverflow.com/questions/5475830/what-is-the-w-thing-in-ruby
For more details you can follow https://simpleror.wordpress.com/2009/03/15/q-q-w-w-x-r-s/
These are the types of percent strings in ruby:
%w : Array of Strings
%i : Array of Symbols
%q : String
%r : Regular Expression
%s : Symbol
%x : Backtick (capture subshell result)
Let take some example
you have some set of characters which perform a paragraph like
Thanks for contributing an answer to Stack Overflow!
so when you try with
%w(Thanks for contributing an answer to Stack Overflow!)
Then you will get the output like
=> ["Thanks", "for", "contributing", "an", "answer", "to", "Stack", "Overflow!"]
if you will use some sets or words as a separate element in array so you should use \
lets take an example
%w(Thanks for contributing an answer to Stack\ Overflow!)
output would be
=> ["Thanks", "for", "contributing", "an", "answer", "to", "Stack Overflow!"]
Here ruby interpreter split the paragraph from spaces within the input. If you give \ after end of word so it merge next word with the that word and push as an string type element in array.
If can use like below
%w[2 4 5 6]
if you will use
%w("abc" "def")
then output would be
=> ["\"abc\"", "\"def\""]
%w(abc def xyz) is a shortcut for ["abc", "def","xyz"]. Meaning it's a notation to write an array of strings separated by spaces instead of commas and without quotes around them.
Related
I want to be able to copy and paste a large string of words from say a text document where there are spaces, returns and not commas between each and every word. Then i want to be able to take out each word individually and put them in a table for example...
input:
please i need help
output:
{1, "please"},
{2, "i"},
{3, "need"},
{4, "help"}
(i will have the table already made with the second column set to like " ")
havent tried anything yet as nothing has come to mind and all i could think of was using gsub to turn spaces into commas and find a solution from there but again i dont think that would work out so well.
Your delimiters are spaces ( ), commas (,) and newlines (\n, sometimes \r\n or \r, the latter very rarely). You now want to find words delimited by these delimiters. A word is a sequence of one or more non-delimiter characters. This trivially translates to a Lua pattern which can be fed into gmatch. Paired with a loop & inserting the matches in a table you get the following:
local words = {}
for word in input:gmatch"[^ ,\r\n]+" do
table.insert(words, word)
end
if you know that your words are gonna be in your locale-specific character set (usually ASCII or extended ASCII), you can use Lua's %w character class for matching sequences of alphanumeric characters:
local words = {}
for word in input:gmatch"%w+" do
table.insert(words, word)
end
Note: The resulting table will be in "list" form:
{
[1] = "first",
[2] = "second",
[3] = "third",
}
(for which {"first", "second", "third"} would be shorthand)
I don't see any good reasons for the table format you have described, but it can be trivially created by inserting tables instead of strings into the list.
I am building a Rails 5.2 app.
In this app I got outputs from different suppliers (I am building a webshop).
The name of the shipping provider is in this format:
dhl_freight__233433
It could also be in this format:
postal__US-320202
How can I remove all that is before (and including) the __ so all that remains are the things after the ___ like for example 233433.
Perhaps some sort of RegEx.
A very simple approach would be to use String#split and then pick the second part that is the last part in this example:
"dhl_freight__233433".split('__').last
#=> "233433"
"postal__US-320202".split('__').last
#=> "US-320202"
You can use a very simple Regexp and a ask the resulting MatchData for the post_match part:
p "dhl_freight__233433".match(/__/).post_match
# another (magic) way to acces the post_match part:
p $'
Postscript: Learnt something from this question myself: you don't even have to use a RegExp for this to work. Just "asddfg__qwer".match("__").post_match does the trick (it does the conversion to regexp for you)
r = /[^_]+\z/
"dhl_freight__233433"[r] #=> "233433"
"postal__US-320202"[r] #=> "US-320202"
The regular expression matches one or more characters other than an underscore, followed by the end of the string (\z). The ^ at the beginning of the character class reads, "other than any of the characters that follow".
See String#[].
This assumes that the last underscore is preceded by an underscore. If the last underscore is not preceded by an underscore, in which case there should be no match, add a positive lookbehind:
r = /(?<=__[^_]+\z/
This requires the match to be preceded by two underscores.
There are many ruby ways to extract numbers from string. I hope you're trying to fetch numbers out of a string. Here are some of the ways to do so.
Ref- http://www.ruby-forum.com/topic/125709
line.delete("^0-9")
line.scan(/\d/).join('')
line.tr("^0-9", '')
In the above delete is the fastest to trim numbers out of strings.
All of above extracts numbers from string and joins them. If a string is like this "String-with-67829___numbers-09764" outut would be like this "6782909764"
In case if you want the numbers split like this ["67829", "09764"]
line.split(/[^\d]/).reject { |c| c.empty? }
Hope these answers help you! Happy coding :-)
I need to split my string based on Boolean operators.
Now i'm using
.split(/(.+?)((?: AND | OR | NOT ))/).reject(&:empty?).reject(&:blank?)
In this method it did not split if the string starts with Boolean operators.
Tested strings
a AND b
AND b
returned output
["a","AND","b"]
["AND b"]
what am i missed.
Your could use scan:
str.scan(/\w+/)
#=> ["Country", "blue", "of", "origin"]
This will work not only with commas, but any non-numeric, non-letter character (except _).
UPDATE
Looking closely at your desired output, it seems that you want to keep the spaces between commas:
I want a desired output like this.
[Country ,blue,of, origin]
If so, use this instead:
str.scan(/[\w\s]+/)
#=> ["Country ", "blue", "of", " origin"]
Here is the solution convert string to array without split
str = "Country ,blue,of, origin"
Array(str.chars.join(""))
I'm trying to parse words out of a string and put them into an array. I've tried the following thing:
#string1 = "oriented design, decomposition, encapsulation, and testing. Uses "
puts #string1.scan(/\s([^\,\.\s]*)/)
It seems to do the trick, but it's a bit shaky (I should include more special characters for example). Is there a better way to do so in ruby?
Optional: I have a cs course description. I intend to extract all the words out of it and place them in a string array, remove the most common word in the English language from the array produced, and then use the rest of the words as tags that users can use to search for cs courses.
The split command.
words = #string1.split(/\W+/)
will split the string into an array based on a regular expression. \W means any "non-word" character and the "+" means to combine multiple delimiters.
For me the best to spliting sentences is:
line.split(/[^[[:word:]]]+/)
Even with multilingual words and punctuation marks work perfectly:
line = 'English words, Polski Żurek!!! crème fraîche...'
line.split(/[^[[:word:]]]+/)
=> ["English", "words", "Polski", "Żurek", "crème", "fraîche"]
Well, you could split the string on spaces if that's your delimiter of interest
#string1.split(' ')
Or split on word boundaries
\W # Any non-word character
\b # Any word boundary character
Or on non-words
\s # Any whitespace character
Hint: try testing each of these on http://rubular.com
And note that ruby 1.9 has some differences from 1.8
For Rails you can use something like this:
#string1.split(/\s/).delete_if(&:blank?)
I would write something like this:
#string
.split(/,+|\s+/) # any ',' or any whitespace characters(space, tab, newline)
.reject(&:empty?)
.map { |w| w.gsub(/\W+$|^\W+^*/, '') } # \W+$ => any trailing punctuation; ^\W+^* => any leading punctuation
irb(main):047:0> #string1 = "oriented design, 'with', !!qwe, and testing. can't rubyisgood#)(*#%)(*, and,rails,is,good"
=> "oriented design, 'with', !!qwe, and testing. can't rubyisgood#)(*#%)(*, and,rails,is,good"
irb(main):048:0> #string1.split(/,+|\s+/).reject(&:empty?).map { |w| w.gsub(/\W+$|^\W+^*/, '')}
=> ["oriented", "design", "with", "qwe", "and", "testing", "can't", "rubyisgood", "and", "rails", "is", "good"]
Is there anything better than string.scan(/(\w|-)+/).size (the - is so, e.g., "one-way street" counts as 2 words instead of 3)?
string.split.size
Edited to explain multiple spaces
From the Ruby String Documentation page
split(pattern=$;, [limit]) → anArray
Divides str into substrings based on a delimiter, returning an array
of these substrings.
If pattern is a String, then its contents are used as the delimiter
when splitting str. If pattern is a single space, str is split on
whitespace, with leading whitespace and runs of contiguous whitespace
characters ignored.
If pattern is a Regexp, str is divided where the pattern matches.
Whenever the pattern matches a zero-length string, str is split into
individual characters. If pattern contains groups, the respective
matches will be returned in the array as well.
If pattern is omitted, the value of $; is used. If $; is nil (which is
the default), str is split on whitespace as if ' ' were specified.
If the limit parameter is omitted, trailing null fields are
suppressed. If limit is a positive number, at most that number of
fields will be returned (if limit is 1, the entire string is returned
as the only entry in an array). If negative, there is no limit to the
number of fields returned, and trailing null fields are not
suppressed.
" now's the time".split #=> ["now's", "the", "time"]
While that is the current version of ruby as of this edit, I learned on 1.7 (IIRC), where that also worked. I just tested it on 1.8.3.
I know this is an old question, but this might be useful to someone else looking for something more sophisticated than string.split. I wrote the words_counted gem to solve this particular problem, since defining words is pretty tricky.
The gem lets you define your own custom criteria, or use the out of the box regexp, which is pretty handy for most use cases. You can pre-filter words with a variety of options, including a string, lambda, array, or another regexp.
counter = WordsCounted::Counter.new("Hello, Renée! 123")
counter.word_count #=> 2
counter.words #=> ["Hello", "Renée"]
# filter the word "hello"
counter = WordsCounted::Counter.new("Hello, Renée!", reject: "Hello")
counter.word_count #=> 1
counter.words #=> ["Renée"]
# Count numbers only
counter = WordsCounted::Counter.new("Hello, Renée! 123", rexexp: /[0-9]/)
counter.word_count #=> 1
counter.words #=> ["123"]
The gem provides a bunch more useful methods.
If the 'word' in this case can be described as an alphanumeric sequence which can include '-' then the following solution may be appropriate (assuming that everything that doesn't match the 'word' pattern is a separator):
>> 'one-way street'.split(/[^-a-zA-Z]/).size
=> 2
>> 'one-way street'.split(/[^-a-zA-Z]/).each { |m| puts m }
one-way
street
=> ["one-way", "street"]
However, there are some other symbols that can be included in the regex - for example, ' to support the words like "it's".
This is pretty simplistic but does the job if you are typing words with spaces in between. It ends up counting numbers as well but I'm sure you could edit the code to not count numbers.
puts "enter a sentence to find its word length: "
word = gets
word = word.chomp
splits = word.split(" ")
target = splits.length.to_s
puts "your sentence is " + target + " words long"
The best way to do is to use split method.
split divides a string into sub-strings based on a delimiter, returning an array of the sub-strings.
split takes two parameters, namely; pattern and limit.
pattern is the delimiter over which the string is to be split into an array.
limit specifies the number of elements in the resulting array.
For more details, refer to Ruby Documentation: Ruby String documentation
str = "This is a string"
str.split(' ').size
#output: 4
The above code splits the string wherever it finds a space and hence it give the number of words in the string which is indirectly the size of the array.
The above solution is wrong, consider the following:
"one-way street"
You will get
["one-way","", "street"]
Use
'one-way street'.gsub(/[^-a-zA-Z]/, ' ').split.size
This splits words only on ASCII whitespace chars:
p " some word\nother\tword|word".strip.split(/\s+/).size #=> 4