I have this string and I'm wondering how to convert it to a Hash.
"{:account_id=>4444, :deposit_id=>3333}"
The way suggested in miku's answer is indeed easiest and unsafest.
# DO NOT RUN IT
eval '{:surprise => "#{system \"rm -rf / \"}"}'
# SERIOUSLY, DON'T
Consider using a different string representation of your hashes, e.g. JSON or YAML. It's way more secure and at least equally robust.
With a little replacement, you may use YAML:
require 'yaml'
p YAML.load(
"{:account_id=>4444, :deposit_id=>3333}".gsub(/=>/, ': ')
)
But this works only for this specific, simple string. Depending on your real data you may get problems.
The easiest and unsafest would be to just evaluate the string:
>> s = "{:account_id=>4444, :deposit_id=>3333}"
>> h = eval(s)
=> {:account_id=>4444, :deposit_id=>3333}
>> h.class
=> Hash
if your string hash is some sort of like this (it can be nested or plain hash)
stringify_hash = "{'account_id'=>4444, 'deposit_id'=>3333, 'nested_key'=>{'key1' => val1, 'key2' => val2, 'key3' => nil}}"
you can convert it into hash like this without using eval which is dangerous
desired_hash = JSON.parse(stringify_hash.gsub("'",'"').gsub('=>',':').gsub('nil','null'))
and for the one you posted where the key is a symbol you can use like this
JSON.parse(string_hash.gsub(':','"').gsub('=>','":'))
Guess I never posted my workaround for this... Here it goes,
# strip the hash down
stringy_hash = "account_id=>4444, deposit_id=>3333"
# turn string into hash
Hash[stringy_hash.split(",").collect{|x| x.strip.split("=>")}]
Related
Say I have
str = "DISABLE_THINGY=true -p my_profile"
To get the value of DISABLE_THINGY (true) I can use
str.partition("DISABLE_THINGY=").last.split(' ').first
I do not want to do that.
There must be a library that parses all this for me.
Anybody know some better ways?
The selected answer is way too convoluted to solve such a simple problem. Regular expressions are great, but the more complex they are, the more likely they'll be wrong:
str = "DISABLE_THINGY=true -p my_profile"
str[/\w+=(\w+)/, 1] # => "true"
/\w+=(\w+)/ simply looks for "words" joined by =.
See String's [] method for more information.
If you had a number of assignments and wanted to capture them all, or, wanted to capture the name and value of this one:
str = "DISABLE_THINGY=true -p my_profile"
str.scan(/\w+=\w+/).map { |s| s.split('=') } # => [["DISABLE_THINGY", "true"]]
That returns an array-of-arrays, which can be useful, or, you could convert that to a Hash:
str.scan(/\w+=\w+/).map { |s| s.split('=') }.to_h # => {"DISABLE_THINGY"=>"true"}
and similarly:
str = "DISABLE_THINGY=true FOO=bar -p my_profile"
str.scan(/\w+=\w+/).map { |s| s.split('=') } # => [["DISABLE_THINGY", "true"], ["FOO", "bar"]]
str.scan(/\w+=\w+/).map { |s| s.split('=') }.to_h # => {"DISABLE_THINGY"=>"true", "FOO"=>"bar"}
Take a look at "Parse command line arguments in a Ruby script".
If all of your arguments don't use a hyphen, you might have to make slight tweaks to the regex used, but this should get you where you need to go. Just replace ARGV.join(' ') in the accepted answer with your str var.
Adjusted the regex in the link provided above to make your use-case work where you combine ENV variables with command line parameters:
args = Hash[ str.scan(/-{0,2}([^=\s]+)(?:[=\s](\S+))?/) ] => {"DISABLE_THINGY"=>"true", "p"=>"my_profile"}
I am using Ruby 1.9.
I have a hash:
Hash_List={"ruby"=>"fun to learn","the rails"=>"It is a framework"}
I have a string like this:
test_string="I am learning the ruby by myself and also the rails."
I need to check if test_string contains words that match the keys of Hash_List. And if it does, replace the words with the matching hash value.
I used this code to check, but it is returning them empty:
another_hash=Hash_List.select{|key,value| key.include? test_string}
OK, hold onto your hat:
HASH_LIST = {
"ruby" => "fun to learn",
"the rails" => "It is a framework"
}
test_string = "I am learning the ruby by myself and also the rails."
keys_regex = /\b (?:#{Regexp.union(HASH_LIST.keys).source}) \b/x # => /\b (?:ruby|the\ rails) \b/x
test_string.gsub(keys_regex, HASH_LIST) # => "I am learning the fun to learn by myself and also It is a framework."
Ruby's got some great tricks up its sleeve, one of which is how we can throw a regular expression and a hash at gsub, and it'll search for every match of the regular expression, look up the matching "hits" as keys in the hash, and substitute the values back into the string:
gsub(pattern, hash) → new_str
...If the second argument is a Hash, and the matched text is one of its keys, the corresponding value is the replacement string....
Regexp.union(HASH_LIST.keys) # => /ruby|the\ rails/
Regexp.union(HASH_LIST.keys).source # => "ruby|the\\ rails"
Note that the first returns a regular expression and the second returns a string. This is important when we embed them into another regular expression:
/#{Regexp.union(HASH_LIST.keys)}/ # => /(?-mix:ruby|the\ rails)/
/#{Regexp.union(HASH_LIST.keys).source}/ # => /ruby|the\ rails/
The first can quietly destroy what you think is a simple search, because of the ?-mix: flags, which ends up embedding different flags inside the pattern.
The Regexp documentation covers all this well.
This capability is the core to making an extremely high-speed templating routine in Ruby.
You could do that as follows:
Hash_List.each_with_object(test_string.dup) { |(k,v),s| s.sub!(/#{k}/, v) }
#=> "I am learning the fun to learn by myself and also It is a framework."
First, follow naming conventions. Variables are snake_case, and names of classes are CamelCase.
hash = {"ruby" => "fun to learn", "rails" => "It is a framework"}
words = test_string.split(' ') # => ["I", "am", "learning", ...]
another_hash = hash.select{|key,value| words.include?(key)}
Answering your question: split your test string in words with #split and then check whether words include a key.
For checking if the string is substring of another string use String#[String] method:
another_hash = hash.select{|key, value| test_string[key]}
I have the following string which has an array element in it and I will like to remove the quotes in the array element to the outside of the array:
"date":"2014-05-04","name":"John","products":["12","14","45"],"status":"completed"
Is there a way to remove the double quotes in [] and add double quotes to the start and end of []? Results:
"date":"2014-05-04","name":"John","products":"[12,14,45]","status":"completed"
Can that be done in ruby or is there a command line that I can use?
Your string looks like a json hash to me:
json = '{"date":"2014-05-04","name":"John","products":["12","14","45"],"status":"completed"}'
require 'json'
hash = JSON.load(json)
hash.update('products' => hash['products'].map(&:to_i))
puts hash.to_json
# => {"date":"2014-05-04","name":"John","products":[12,14,45],"status":"completed"}
Or if you really want to have the array represented as a string (what is not json anymore):
hash.update('products' => hash['products'].map(&:to_i).to_s) # note .to_s here
puts hash.to_json
# => {"date":"2014-05-04","name":"John","products":"[12,14,45]","status":"completed"}
The answer by #spickermann is pretty good, and the best way I can think of, but since I had fun trying to find an alternative without using json, here it goes:
def string_to_result(str)
str.match(/(?:\[)((?:")+(.)+(?:")+)+(?:\])/)
str.gsub($1, "#{$1.split(',').map{ |num| num.gsub('"', '') }.join(',')}").gsub(/\[/, '"[').gsub(/\]/, ']"').gsub(/String/, 'Results')
end
Is ugly as hell, but it works :P
I tried to do it on a single step, but that was way harder for my regexp skills.
Anyway, you should never parse something structured such as json or xml using only regexps, and this is merely for fun.
[EDIT] Had the bracket adjacent quotes wrong,sorry. Fixed.
Also, one more thing, this fails A LOT! An empty array or an array in other place in the string are just a few cases where it would fail.
You could use the form of String#gsub that takes a block:
str = '"2014-05-04","name":"John","products":["12","14","45"],"status":"completed"'
puts str.gsub(/\["(\d+)","(\d+)","(\d+)"\]/) { "\"[#{$1},#{$2},#{$3}]\"" }
#"2014-05-04","name":"John","products":"[12,14,45]","status":"completed"
I'm looking at ruby's replace: http://www.ruby-doc.org/core/classes/String.html#M001144
It doesn't seem to make sense to me, you call replace and it replaces the entire string.
I was expecting:
replace(old_value, new_value)
Is what I am looking for gsub then?
replace seems to be different than in most other languages.
I agree that replace is generally used as some sort of pattern replace in other languages, but Ruby is different :)
Yes, you are thinking of gsub:
ruby-1.9.2-p136 :001 > "Hello World!".gsub("World", "Earth")
=> "Hello Earth!"
One thing to note is that String#replace may seem pointeless, however it does remove 'taintediness". You can read more up on tained objects here.
I suppose the reason you feel that replace does not make sense is because there is assigment operator = (not much relevant to gsub).
The important point is that String instances are mutable objects. By using replace, you can change the content of the string while retaining its identity as an object. Compare:
a = 'Hello' # => 'Hello'
a.object_id # => 84793190
a.replace('World') # => 'World'
a.object_id # => 84793190
a = 'World' # => 'World'
a.object_id # => 84768100
See that replace has not changed the string object's id, whereas simple assignment did change it. This difference has some consequences. For example, suppose you assigned some instance variables to the string instance. By replace, that information will be retained, but if you assign the same variable simply to a different string, all that information is gone.
Yes, it is gsub and it is taken from awk syntax. I guess replace stands for the internal representation of the string, since, according to documentation, tainted-ness is removed too.
In Ruby 1.8.7, Array("hello\nhello") gives you ["hello\n", "hello"]. This does two things that I don't expect:
It splits the string on newlines. I'd expect it simply to give me an array with the string I pass in as its single element without modifying the data I pass in.
Even if you accept that it's reasonable to split a string when passing it to Array, why does it retain the newline character when "foo\nbar".split does not?
Additionally:
>> Array.[] "foo\nbar"
=> ["foo\nbar"]
>> Array.[] *"foo\nbar"
=> ["foo\n", "bar"]
It splits the string on newlines. I'd expect it simply to give me an array with the string I pass in as its single element without modifying the data I pass in.
That's a convention as good as any other. For example, the list constructor in Python does something entirely different:
>>> list("foo")
['f', 'o', 'o']
So long as it's consistent I don't see the problem.
Even if you accept that it's reasonable to split a string when passing it to Array, why does it retain the newline character when "foo\nbar".split does not?
My wild guess here (supported by quick googling and TryRuby) is that the .split method for strings does so to make it the "inverse" operation of the .join method for arrays.
>> "foospambar".split("spam").join("spam")
=> "foospambar"
By the way, I cannot replicate your behaviour on TryRuby:
>> x = Array("foo\nbar")
=> ["foo\nbar"]
>> Array.[] *"foo\nbar"
=> ["foo\nbar"]
If you replace the double-quotes with single-quotes it works as expected:
>> Array.[] "foo\nbar"
=> ["foo\nbar"]
>> Array.[] 'foo\nbar'
=> ["foo\\nbar"]
You may try:
"foo\nbar".split(/w/)
"foo\nbar".split(/^/)
"foo\nbar".split(/$/)
and other regular expressions.