I have this function in Ruby
def translate word
vowels=["a","e","I","O","U"]
i=1.to_i
sentense=word.split(" ").to_a
puts sentense if sentense.length >=1
sentense.split("")
puts sentense
end
I have this phrase "this is a test phrase " and at first I want to create an array that looks like:
["this","is","a", "test", "phrase"]
Then I want to create another array it to look like:
[["t","h","i","s"],["i","s"],["a"],["t","e","s","t"],["p","h","r","a","s","e"].
I tried
sentense=word.split(" ").to_a
new_array=sentense.split("").to_a
but it didn't work
You could use String#split, Enumerable#map and String#chars:
p "this is a test phrase".split.map(&:chars)
# => [["t", "h", "i", "s"], ["i", "s"], ["a"], ["t", "e", "s", "t"], ["p", "h", "r", "a", "s", "e"]]
string.split(' ') could be written as string.split, so you can omit passing the whitespace in parenthesis.
And this also gives you an array, there's no need to use to_a, you'll have an array like ["this", "is", "a", "test", "phrase"], so you can use map to get a new array and for each element inside an array of its characters by using .split('') or .chars.
def chop_up(str)
str.strip.each_char.with_object([[]]) { |c,a| c == ' ' ? (a << []) : a.last << c }
end
chop_up "fee fi fo fum"
#=> [["f", "e", "e"], ["f", "i"], ["f", "o"], ["f", "u", "m"]]
chop_up " fee fi fo fum "
#=> [["f", "e", "e"], ["f", "i"], ["f", "o"], ["f", "u", "m"]]
chop_up "feefifofum "
#=> [["f", "e", "e", "f", "i", "f", "o", "f", "u", "m"]]
chop_up ""
#=> [[]]
Related
I'd like to zip all the array values of a hash. I know there's a way to zip arrays together. I'd like to do that with the values of my hash below.
current_hash = {:a=>["k", "r", "u"],
:b=>["e", " ", "l"],
:c=>["d", "o", "w"],
:d=>["e", "h"]
}
desired_outcome = "keder ohulw"
I have included my desired outcome above.
current_hash.values.then { |first, *rest| first.zip(*rest) }.flatten.compact.join
An unfortunate thing with Ruby zip is that the first enumerable needs to be the receiver, and the others need to be parameters. Here, I use then, parameter deconstruction and splat to separate the first enumerable from the rest. flatten gets rid of the column arrays, compact gets rid of the nil (though it's not really necessary as join will ignore it), and join turns the array into the string.
Note that Ruby zip will stop at length of the receiver; so if :a is shorter than the others, you will likely have a surprising result. If that is a concern, please update with an example that reflects that scenario, and the desired outcome.
Here I'm fleshing out #Amadan's remark below the horizontal line in is answer. Suppose:
current_hash = { a:["k","r"], b:["e"," ","l"], c:["d","o","w"], d:["e", "h"] }
and you wished to return "keder ohlw". If you made ["k","r"] and [["e"," ","l"], ["d","o","w"], ["e", "h"]] zip's receiver and argument, respectively, you would get "keder oh", which omits "l" and "w". (See Array#zip, especially the 3rd paragraph.)
To include those strings you would need to fill out ["k","r"] with nils to make it as long as the longest value, or make zip's receiver an array of nils of the same length. The latter approach can be implemented as follows:
vals = current_hash.values
#=> [["k", "r"], ["e", " ", "l"], ["d", "o", "w"], ["e", "h"]]
([nil]*vals.map(&:size).max).zip(*vals).flatten.compact.join
#=> "keder ohlw"
Note:
a = [nil]*vals.map(&:size).max
#=> [nil, nil, nil]
and
a.zip(*vals)
#=> [[nil, "k", "e", "d", "e"],
# [nil, "r", " ", "o", "h"],
# [nil, nil, "l", "w", nil]]
One could alternatively use Array#transpose rather than zip.
vals = current_hash.values
idx = (0..vals.map(&:size).max-1).to_a
#=> [0, 1, 2]
vals.map { |a| a.values_at(*idx) }.transpose.flatten.compact.join
#=> "keder ohlw"
See Array#values_at. Note:
a = vals.map { |a| a.values_at(*idx) }
#=> [["k", "r", nil],
# ["e", " ", "l"],
# ["d", "o", "w"],
# ["e", "h", nil]]
a.transpose
#=> [["k", "e", "d", "e"],
# ["r", " ", "o", "h"],
# [nil, "l", "w", nil]]
I'm trying to solve Chasing Subs problem. I'm trying to generate that regex according to the input data. The goal is go get all substrings (including overlapped ones) with all unique letters.
I'm trying to use regexp like this:
regexp = /(?=(?<gs>.)(?<gu>[^\k<gs>])(?<gb>[^\k<gs>\k<gu>])(?<gm>[^\k<gs>\k<gu>\k<gb>])(?<ga>[^\k<gs>\k<gu>\k<gb>\k<gm>])(?<gr>[^\k<gs>\k<gu>\k<gb>\k<gm>\k<ga>])(?<gi>[^\k<gs>\k<gu>\k<gb>\k<gm>\k<ga>\k<gr>])(?<gn>[^\k<gs>\k<gu>\k<gb>\k<gm>\k<ga>\k<gr>\k<gi>])(?<ge>[^\k<gs>\k<gu>\k<gb>\k<gm>\k<ga>\k<gr>\k<gi>\k<gn>]))/
"archipelago".scan(regexp) #=> []
"archipelbgo".scan(regexp) #=> []
"brchipelbgo".scan(regexp) #=> []
"zrchipelzgo".scan(regexp) #=> [["z", "r", "c", "h", "i", "p", "e", "l", "z"]]
Why does it behave like this? Why can't it find anything with "b" and "a"? And why does it return only one (incorrect) result with "z"? What am I doing wrong?
I don't think a regular expression is the correct tool for this problem. We could do the following, however.
def substrings(str)
arr = str.chars
(1..str.size).each_with_object([]) { |n,a|
arr.each_cons(n) { |b| a << b.join if b == b.uniq } }
end
substrings("archipelago")
#=> ["a", "r", "c", "h", "i", "p", "e", "l", "a", "g", "o", "ar", "rc", "ch", "hi",
# "ip", "pe", "el", "la", "ag", "go", "arc", "rch", "chi", "hip", "ipe", "pel",
# "ela", "lag", "ago", "arch", "rchi", "chip", "hipe", "ipel", "pela", "elag",
# "lago", "archi", "rchip", "chipe", "hipel", "ipela", "pelag", "elago", "archip",
# "rchipe", "chipel", "hipela", "ipelag", "pelago", "archipe", "rchipel", "chipela",
# "hipelag", "ipelago", "archipel", "rchipela", "chipelag", "hipelago", "rchipelag",
# "chipelago", "rchipelago"]
With Ruby how do I split on either one of tow conditions -- wheter there are 3 or more spaces or a tab charadter? I tried this
2.4.0 :003 > line = "a\tb\tc"
=> "a\tb\tc"
2.4.0 :004 > line.split(/([[:space:]][[:space:]][[:space:]]+|\t)/)
=> ["a", "\t", "b", "\t", "c"]
but as you can see, the tab character itself is getting included in my results. The results should be
["a", "b", "c"]
What about just split?
p "a\tb\tc".split
# ["a", "b", "c"]
p "a\tb\tc\t\tc\t\t\t\t\t\t\tc\ts\ts\tt".split
# ["a", "b", "c", "c", "c", "s", "s", "t"]
Although that doesn't split when there are three 3 or more white spaces, this might work:
p "a\tb\tc\t\tc\t\t\ t\t\tc\ts\ts\tt".split(/\s{3,}|\t/)
# => ["a", "b", "c", "c", "t", "c", "s", "s", "t"]
line = "aa bb cc\tdd"
line.split /\p{Space}{3,}|\t+/
#⇒ ["aa bb", "cc", "dd"]
This question already has answers here:
How to dynamically create a local variable?
(4 answers)
Closed 7 years ago.
I'm trying to slice an array into equal sizes (rounded down) and save each section to respective variables.
The method each_slice has worked to grab n-sized blocks. However I can't think of a way to:
iterate over the each's blocks' "sub index"
create a new array for each and give each a unique name.
letters = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n"]
def groups_of_five(array)
split_array = array.each_slice(5).to_a
#something like the following:
#array(n) = Array[split_array.each {|x| x}]
end
end
The output I'm hoping for:
groups_of_five(letters)
=> array1: ["a,"b","c","d","e"]
=> array2: ["f","g","h","i","j"]
=> array3: ["k","l","m","n"]
Combine each_slice with with_index and you'll have everything you need:
letters.each_slice(5).with_index(1) do |group, index|
puts "array#{index}: #{group.inspect}"
end
Output is:
array1: ["a", "b", "c", "d", "e"]
array2: ["f", "g", "h", "i", "j"]
array3: ["k", "l", "m", "n"]
It's no longer possible to set local variable dynamically in Ruby versions greather than 1.8, so if you want to assign to variables it will have to be instance variables or you could output a Hash.
The following will create instance variables:
def groups_of_five(array)
array.each_slice(5).with_index(1) do |group, index|
instance_variable_set "#array#{index}".to_sym, group
end
end
groups_of_five(letters)
puts #array1 #=> ["a", "b", "c", "d", "e"]
puts #array2 #=> ["f", "g", "h", "i", "j"]
puts #array3 #=> ["k", "l", "m", "n"]
Or this will output a Hash:
def groups_of_five(array)
hash = {}
array.each_slice(5).with_index(1) do |group, index|
hash["array#{index}".to_sym] = group
end
hash
end
hash = groups_of_five(letters)
puts hash[:array1] #=> ["a", "b", "c", "d", "e"]
puts hash[:array2] #=> ["f", "g", "h", "i", "j"]
puts hash[:array3] #=> ["k", "l", "m", "n"]
If you are looking for a hash structure to return from groups_of_five(letters), here's the solution
def groups_of_five(array)
split_array = letters.each_slice(5).to_a
split_array.reduce({}){ |i,a|
index = split_array.index(a) + 1
i["array#{index}"] = a; i
}
end
# groups_of_five(letters)
#=> {"array1"=>["a", "b", "c", "d", "e"], "array2"=>["f", "g", "h", "i", "j"], "array3"=>["k", "l", "m", "n"]}
You could do this:
def group_em(a,n)
arr = a.dup
(1..(arr.size.to_f/n).ceil).each_with_object({}) { |i,h|
h["array#{i}"] = arr.shift(n) }
end
group_em(letters,1)
#=> {"array1"=>["a"], "array2"=>["b"],...,"array14"=>["n"]}
group_em(letters,2)
#=> {"array1"=>["a", "b"], "array2"=>["c", "d"],...,"array7"=>["m", "n"]}
group_em(letters,5)
#=> {"array1"=>["a", "b", "c", "d", "e"],
# "array2"=>["f", "g", "h", "i", "j"],
# "array3"=>["k", "l", "m", "n"]}
A variant is:
def group_em(arr,n)
(1..(arr.size.to_f/n).ceil).zip(arr.each_slice(n).to_a)
.each_with_object({}) { |(i,a),h| h["array#{i}"]=>a) }
end
So far I have:
my_array = "Foo bar na nas"
my_array.delete!(" ").downcase!
my_array = my_array.split(//).uniq
To get:
==> ["f", "o", "b", "a", "r", "n", "s"]
I can't seem to use .split!(//) like .delete! or .downcase! but I want to do all of this in one step. Is it possible?
Using my_array.delete!(" ").downcase!.split!(//) yields "': undefined method 'split!' for nil:NilClass" so I assume .split! just doesn't exist.
No. If you will read documentation you will get that destructive methods return nil when there is nothing to change, so you cannot chain them. If you want to change string to array of it's letters excluding whitespces you should rathe run:
my_array = "Foo bar na nas".downcase.gsub(/\W/, '').split(//).uniq
There also don't exist destructive method split!. Just how can it exist? Ruby is strong-typed language so you cannot change String into Array because they aren't related.
my_array.downcase.gsub(' ','').chars.uniq
Why not use split with a regular expression matching white space or nothing?
"Foo bar na nas".downcase.split(/\s*/).uniq
This returns
["f", "o", "b", "a", "r", "n", "s"]
split! does not exist because by convention methods with ! alter the object itself in ruby, and you can not coerce a string into an array because ruby is strongly typed.
"Foo bar na nas".downcase.split(//).uniq.keep_if { |item| item != " " }
#=> ["f", "o", "b", "a", "r", "n", "s"]
"Foo bar na nas t p".downcase.split(//).uniq.keep_if { |item| item != " " }
#=> ["f", "o", "b", "a", "r", "n", "s", "t", "p"]