I've created the following hash keys with values parsed from PDF into array:
columns = ["Sen", "P-Hire#", "Emp#", "DOH", "Last", "First"]
h = Hash[columns.map.with_index.to_h]
=> {"Sen"=>0, "P-Hire#"=>1, "Emp#"=>2, "DOH"=>3, "Last"=>4, "First"=>5}
Now I want to update the value of each key with 6 equivalent values from another parsed data array:
rows = list.text.scan(/^.+/)
row = rows[0].tr(',', '')
#data = row.split
=> ["2", "6", "239", "05/05/67", "Harp", "Erin"]
I can iterate over #data in the view and it will list each of the 6 values. When I try to do the same in the controller it sets the same value to each key:
data.each do |e|
h.update(h){|key,v1| (e) }
end
=>
{"Sen"=>"Harper", "P-Hire#"=>"Harper", "Emp#"=>"Harper", "DOH"=>"Harper", "Last"=>"Harper", "First"=>"Harper"
So it's setting the value of each key to the last value of the looped array...
I would just do:
h.keys.zip(#data).to_h
If the only purpose of h is as an interim step getting to the result, you can dispense with it and do:
columns.zip(#data).to_h
There are several ways to solve this problem but a more direct and straight forward way would be:
columns = ["Sen", "P-Hire#", "Emp#", "DOH", "Last", "First"]
...
#data = row.split
h = Hash.new
columns.each_with_index do |column, index|
h[column] = #data[index]
end
Another way:
h.each do |key, index|
h[key] = #data[index]
end
Like I said, there are several ways of solving the issue and the best is always going to depend on what you're trying to achieve.
Related
first_response = [
{"xId" => "123", "yId" => "321"},
{"xId" => "x", "yId" => "y" }
]
first_response.each do |resp|
x_id = resp['xId']
y_id = resp['yId']
puts x_id.to_s
puts y_id.to_s
end
This gives me outputs
123
321
x
y
output hash I want to create is
{123=>{321}, x=>{y}}
first service: I have an array of hash that has two different ids example:(x_id and y_id) (there would be multiple pairs like that in the response)
I want to create a hash that should contain the matching pair of x_id and y_ids that we get from the first service with x_id's as the key for all the pairs.
If you know every hash in first_response is going to contain exactly two key/value pairs, you can extract their values and then convert that result into a hash (see Enumerable#to_h):
first_response.to_h(&:values)
# {"123"=>"321", "x"=>"y"}
Looks like this approach works, but I am not completely sure if that is right
first_response = [{"xId"=>"123","yId"=> "321"}, {"xId"=>"x","yId"=> "y"}]
h = {}.tap do |element|
first_response.each do |resp|
x_id = resp['xId']
y_id = resp['yId']
element[x_id] = y_id
end
end
puts h.to_s
# {"123"=>"321", "x"=>"y"}
I've an array contains hashes, I want to filter few parameters from the hash and insert the filtered data in another array but am not succeed below is the sample data I've used
a = Array.new
a = [
{"name"=>"hello", "age"=>"12", "sex"=> "M", "city"=>"Chennai"},
{"name"=>"name2", "age"=>"26", "sex"=> "M", "city"=>"Banglore"}
]
line_item = Array.new
hash_data = {}
a.each do |datas|
hash_data[:name] = datas["name"]
hash_data[:age] = datas["age"]
line_item << hash_data
end
I am getting this result:
[
{:name=>"name2", :age=>"26"},
{:name=>"name2", :age=>"26"}
]
But am expecting this:
[
{:name=>"hello", :age=>"12"},
{:name=>"name2", :age=>"26"}
]
Somebody please help to sort out this, Thanks in advance
Defining the hash outside the loop means that you keep adding the same hash object again (while overwriting its previous values). Instead, create a fresh hash within the loop:
line_items = []
a.each do |datas|
hash_data = {}
hash_data[:name] = datas["name"]
hash_data[:age] = datas["age"]
line_items << hash_data
end
The code looks a bit unidiomatic. Let's refactor it.
We can set the keys right within the hash literal:
line_items = []
a.each do |datas|
hash_data = { name: datas["name"], age: datas["age"] }
line_items << hash_data
end
We can get rid of the hash_data variable:
line_items = []
a.each do |datas|
line_items << { name: datas["name"], age: datas["age"] }
end
And we can use map to directly transform the array:
line_items = a.map { |h| { name: h["name"], age: h["age"] } }
#=> [{:name=>"hello", :age=>"12"}, {:name=>"name2", :age=>"26"}]
You can get the expected result with a combination of map and slice
a = [
{"name"=>"hello", "age"=>"12", "sex"=> "M", "city"=>"Chennai"},
{"name"=>"name2", "age"=>"26", "sex"=> "M", "city"=>"Banglore"}
]
a.map{ |e| e.slice("name", "age") }
#=> [{"name"=>"hello", "age"=>"12"}, {"name"=>"name2", "age"=>"26"}]
map: Returns Array containing the values returned by block
slice: Returns Hash including only the specified keys
In your loop you are essentially populating line_item with hash_data twice. This is the same object however. You can remedy this by using .dup.
a.each do |datas|
hash_data[:name]=datas["name"]
hash_data[:age]=datas["age"]
line_item << hash_data.dup # <- here
end
irb(main):044:0> line_item
=> [{:name=>"hello", :age=>"12"}, {:name=>"name2", :age=>"26"}]
Edit: I prefer rado's suggestion of moving your definition of hash_data inside the loop over using .dup. It solves the problem more than treating the symptom.
I think a lot of people are over complicating this.
You can achieve this using the following:
a.map { |hash| hash.select { |key, _value| key == 'name' || key == 'age' } }
If you want to return an array, you should nearly always be using map, and select simply selects the key - value pairs that match the criteria.
If you're set on having symbols as the keys, you can call symbolize_keys on the result.
I'll expand the code so it's a little more readable, but the one liner above works perfectly:
a.map do |hash|
hash.select do |key, _value|
key == 'name' || key == 'age'
end
end
On the first line hash_data[:name]=datas["name"] you are setting the key of the hash. That's why when the loop iterate again, it is overriding the value and after that push the new result to the hash.
One solution with reusing this code is just to put the hash_data = {} on the first line of your loop. This way you will have a brand new hash to work with on every iteration.
Also I would recommend you to read the docs about the Hash module. You will find more useful methods there.
If you want for all keys you can do this
array = [{"name"=>"hello", "age"=>"12", "sex"=> "M", "city"=>"Chennai"}, {"name"=>"name2", "age"=>"26""sex"=> "M", "city"=>"Banglore"}]
new_array = array.map{|b| b.inject({}){|array_obj,(k,v)| array_obj[k.to_sym] = v; array_obj}}
Ref: inject
Happy Coding
I am trying to iterate over a hash returned from an active record search.
the data comes back {[k, v] => v, [k,v] => v, etc.} and I need to place that data in 3 separate columns of a table.
what I have so far in a helper is
data = {}
connector = 0
us_cords = 0
eu_cords = 0
molex_connector = 0
chart_data_two.each do |key, value|
data[key[0]] ||= Hash.new
data[key[0]][key[1]] = value
end
return data
This gives me the k out of the k,v pair above and then a hash with "v" => v from above.
so I am having a hard time wrapping my head around iterating over the data hash and putting it into the view table in each column.
The view has #table_data_two = chart_qty_monthly_data(#chart_data_two) and then #table_data_two.each do |k,v| for generating each row/column.
Eventually it might be nice to do only one merged cell for month with 4 cells for model and then the quantities
Here's one way to build that:
data = Hash.new { |h, k| h[k] = {} }
chart_data_two.each do |key, value|
model_quantity = { key[0] => value }
data[key[1]].merge!(model_quantity)
end
If you want it to be in order by month, you can change the keys to integers and sort it:
data = Hash.new { |h, k| h[k] = {} }
chart_data_two.each do |key, value|
model_quantity = { key[0] => value }
data[key[1].to_i].merge!(model_quantity)
end
sorted_data = data.sort.to_h
It's not perfect, so I'll look it over again and see what could be improved, but it will at least get you started, assuming I understood your question correctly.
ended up doing it a bit different:
data = {}
#initialize hash keys in the order you want them to end up in
(1..12).each do |month|
data[month] = {"Connector" => 0, "US Cords" => 0, "EU Cords" => 0}
end
chart_data_two.each do |key, value|
#key[1] is month. we're referencing the keys we initialized above
#key[2] is model. we're adding a new key to the nested hash we initialized above
#logger.info "#{key[0]}, #{key[1]}, #{value}"
data[key[1].to_i][key[0]] = value
#logger.info "%%%%%%%% inside iterator #{data}"
end
#logger.info "$$$$$ passing #{data} into chart"
return data
end
I got help with figuring that out, but I wanted to post it here.
I have the following snippet of code to fetch certain columns from the db:
#data = Topic.select("id,name").where("id in (?)",#question.question_topic.split(",")).map(&:attributes)
In the resulting Array of Hashes which is :
Current:
#data = [ { "id" => 2, "name" => "Sports" }]
To be changed to:
#data = [ { "id" => "2", "name" => "Sports" }]
I want to convert "id" to string from fixnum. Id is integer in the db. What is the cleanest way to do this?
Note: After using .map(&:attributes) it is not an active record relation.
You can do it with proper map usage:
topics = Topic.select("id,name").where("id in (?)",#question.question_topic.split(","))
#data = topics.map do |topic|
{
'id' => topic.id.to_s,
'name' => topic.name
}
end
What you're looking for is simply
#data.each { |obj| obj["id"] = obj["id"].to_s }
There isn't really a simpler way (I think that's straightforward enough anyway).
Going by the title which implies a different question - converting every value in the hash to a string you can do this:
#data.each do |obj|
obj.map do |k, v|
{k => v.to_s}
end
end
Just leaving that there anyway.
You can use Ruby's #inject here:
#data.map do |datum|
new_datum = datum.inject({}) do |converted_datum, (key, value)|
converted_datum[key] = value.to_s
converted_datum
end
end
This will work to convert all values to strings, regardless of the key.
If you are using Rails it can be even cleaner with Rails' #each_with_object:
#data.map do |datum|
datum.each_with_object({}) do |(key, value), converted_datum|
converted_datum[key] = value.to_s
end
end
This will iterate all the key names in the hash and replace the value with the #to_s version of the datum associated with the key. nil's converted to empty strings. Also, this assumes you don't have complex data within the hash like embedded arrays or other hashes.
def hash_values_to_string(hash)
hash.keys.each {|k| hash[k]=hash[k].to_s}; hash
end
I have this code here and it works but there has to be a better way.....i need two arrays that look like this
[
{
"Vector Arena - Auckland Central, New Zealand" => {
"2010-10-10" => [
"Enter Sandman",
"Unforgiven",
"And justice for all"
]
}
},
{
"Brisbane Entertainment Centre - Brisbane Qld, Austr..." => {
"2010-10-11" => [
"Enter Sandman"
]
}
}
]
one for the past and one for the upcoming...the problem i have is i am repeating myself and though it works i want to clean it up ...here is my data
..
Try this:
h = Hash.new {|h1, k1| h1[k1] = Hash.new{|h2, k2| h2[k2] = []}}
result, today = [ h, h.dup], Date.today
Request.find_all_by_artist("Metallica",
:select => "DISTINCT venue, showdate, LOWER(song) AS song"
).each do |req|
idx = req.showdate < today ? 0 : 1
result[idx][req.venue][req.showdate] << req.song.titlecase
end
Note 1
In the first line I am initializing an hash of hashes. The outer hash creates the inner hash when a non existent key is accessed. An excerpt from Ruby Hash documentation:
If this hash is subsequently accessed by a key that doesn‘t correspond to a hash
entry, the block will be called with the hash object and the key, and should
return the default value. It is the block‘s responsibility to store the value in
the hash if required.
The inner hash creates and empty array when the non existent date is accessed.
E.g: Construct an hash containing of content as values and date as keys:
Without a default block:
h = {}
list.each do |data|
h[data.date] = [] unless h[data.date]
h[data.date] << data.content
end
With a default block
h = Hash.new{|h, k| h[k] = []}
list.each do |data|
h[data.date] << data.content
end
Second line simply creates an array with two items to hold the past and future data. Since both past and the present stores the data as Hash of Hash of Array, I simply duplicate the value.
Second line can also be written as
result = [ h, h.dup]
today = Date.today