Im trying to arrange #plrdet by the values in arr.
when im selecting this way:
#plrdet = Player.find_all_by_fid(arr)
it returns in the order of the rows in the table, i want it to be ordered by the order of arr.
for example:
Player contains the following attributes: address, age, uniqnum.
and:
arr
is an array of the uniqnum.
arr=[456,123,789]
player=[{NYC,32,123},{BSAS,27,456},{LND,30,789})
the result that im looking for should be from the "find_all"
player=[,{BSAS,27,456},{NYC,32,123},{LND,30,789})
If I understand the problem I would try something like this:
Hash version
players = [{}]
#plrdet.each do |player|
players << {"adress" => player.adress, "age" => player.age, "fid" => player.fid}
end
players.inspect
Now result should be [{"adress" => BSAS, "age" => 27, "fid" => 456},{"adress" => NYC, "age" => 32,"fid" => 123},{"adress" => LND, "age" => 30, "fid" => 789}]
Array version
players = [[]]
#plrdet.each do |player|
players << [player.adress, player.age, player.fid]
end
Now result should be [[BSAS,27,456],[NYC,32,123],[LND,30,789]]
Sort
I think this solution should work but I don't like it and there are maybe better way to solve your problem :
sorted_players = [[]]
arr.each do |arr_fid|
sorted_players << players.collect{|player| player if player.include?(arr_fid)}
end
You have two options:
Use order to sort the results with the query
Use sort to sort the results in memory
You may use 1. It will be something like:
#plrdet = Player.find_all_by_fid(arr).order("address")
Related
sorry about the title, cannot express myself better.
I have this:
{
7758 => { 3259 => 10, 39625 => 10, 36410 => 20, 36238 => 20, 34951 => 20, 32101 => 10},
7916 => { 3259 => 10, 39625 => 10, 36410 => 20, 36238 => 20, 34951 => 20, 32101 => 10},
8857 => { 1000 => 10, 39625 => 10 }
}
the keys of those hashes represents record ids, the values represent the data that should go in their row attribute.
problem is that this hash can weigh a lot, so it's imprudent to issue an update on the database for each record represented in the hash.
instead I thought about grouping up hashes with identical values and have a structure for which I can just issue an update to records in one shot.
comparing hashes values can be done even by transforming the nested hashes themselves into a json string, since it's the datatype we use for that column.
in the end I'd like to issue an update_all for a series of variants that has the same hash content, I understand that the number of updates issues to the database is 1:1 to how unique are the hash values, but I kinda have the choice to sort their keys in someway before the comparison should we have something smart to compare existing values rather than converting the content to a string for comparison purposes.
what happens now is a normal update on each hash record in a cycle:
UPDATE "table" SET "rates" = '{"3259":10,"39625":10,"36410":20,"36238":20,"34951":20,"32101":10}', WHERE "table"."variant_id" = 7758
UPDATE "table" SET "rates" = '{"3259":10,"39625":10,"36410":20,"36238":20,"34951":20,"32101":10}', WHERE "table"."variant_id" = 7916
UPDATE "table" SET "rates" = '{"1000":10,"39625":10}' WHERE "table"."variant_id" = 7916
I'd like to transform the original structure in something that allows me to perform this:
UPDATE "table" SET "rates" = '{"3259":10,"39625":10,"36410":20,"36238":20,"34951":20,"32101":10}', WHERE "table"."variant_id" IN(7758, 7916)
UPDATE "table" SET "rates" = '{"1000":10,"39625":10}' WHERE "table"."variant_id" = 7916
I tried a
hash.group_by { |h| h[1].to_json }.each do |rate|
but I have this in rate:
["{\"3259\":10,\"39625\":10,\"36410\":20,\"36238\":20,\"34951\":20,\"32101\
":10}", [[7758, {3259=>10, 39625=>10, 36410=>20, 36238=>20, 34951=>20,
32101=>10}], [7916, {3259=>10, 39625=>10, 36410=>20, 36238=>20,
34951=>20, 32101=>10}], [8857, {3259=>10, 39625=>1...
Maybe something like this:
result = hash.each_with_object({}) do |(id, attributes), result|
json_string = attributes.to_json
result[json_string] ||= []
result[json_string] << id
end
result.each do |json_string, ids|
# ...
end
I am trying this for the first time and am not sure I have quite achieved what i want to. I am pulling in data via a screen scrape as arrays and want to put them into a hash.
I have a model with columns :home_team and :away_team and would like to post the data captured via the screen scrape to these
I was hoping someone could quickly run this in a rb file
require 'open-uri'
require 'nokogiri'
FIXTURE_URL = "http://www.bbc.co.uk/sport/football/premier-league/fixtures"
doc = Nokogiri::HTML(open(FIXTURE_URL))
home_team = doc.css(".team-home.teams").map {|team| team.text.strip}
away_team = doc.css(".team-away.teams").map {|team| team.text.strip}
team_clean = Hash[:home_team => home_team, :away_team => away_team]
puts team_clean.inspect
and advise if this is actually a hash as it seems to be an array as i cant see the hash name being outputted. i would of expected something like this
{"team_clean"=>[{:home_team => "Man Utd", "Chelsea", "Liverpool"},
{:away_team => "Swansea", "Cardiff"}]}
any help appreciated
You actually get a Hash back. But it looks different from the one you expected. You expect a Hash inside a Hash.
Some examples to clarify:
hash = {}
hash.class
=> Hash
hash = { home_team: [], away_team: [] }
hash.class
=> Hash
hash[:home_team].class
=> Array
hash = { hash: { home_team: [], away_team: [] } }
hash.class
=> Hash
hash[:hash].class
=> Hash
hash[:hash][:home_team].class
=> Array
The "Hash name" as you call it, is never "outputed". A Hash is basically a Array with a different index. To clarify this a bit:
hash = { 0 => "A", 1 => "B" }
array = ["A", "B"]
hash[0]
=> "A"
array[0]
=> "A"
hash[1]
=> "B"
array[1]
=> "B"
Basically with a Hash you additionally define, how and where to find the values by defining the key explicitly, while an array always stores it with a numerical index.
here is the solution
team_clean = Hash[:team_clean => [Hash[:home_team => home_team,:away_team => away_team]]]
I have an array of hashes, this is not an active record model. This array is of objects of type Person with properties of id, name, age. I have a second array of strings, ["john", "james", "bill"].
I am attempting to remove all objects in the array of hashes except for the ones who have names in the second array, essentially performing an intersect, but I'm having quite a few problems. Any suggestions? I'm not sure if my syntax is just off or if I'm thinking about this the wrong way. Obviously I can just iterate through but this seems like its probably not the best way to handle the situation.
http://www.ruby-doc.org/core-1.9.2/Array.html#method-i-select
arr1 = [{:id => 1, :name => "John"}, {:id => 2, :name => "Doe"}];
arr2 = ["Doe"];
intersect = arr1.select {|o| arr2.include? o[:name]} # you can also use select!
p intersect # outputs [{:name=>"Doe", :id=>2}]
Late to the party, but if arr1 :name is an array this works nicely:
arr1 = [{:id => 1, :name => ["John", "Doe"]}, {:id => 2, :name => ["Doe"]}];
arr2 = ["Doe"]
> intersect = arr1.reject{|o| (arr2 & o[:name]).empty?}
=> [{:id=>1, :name=>["John", "Doe"]}, {:id=>2, :name=>["Doe"]}] #output
> arr2 = ["John"]
> intersect = arr1.reject{|o| (arr2 & o[:name]).empty?}
=> [{:id=>1, :name=>["John", "Doe"]}] #output
or use select:
intersect = arr1.select{|o| !(arr2 & o[:name]).empty?}
To remove all objects in the array of hashes except for the ones who have names in the second array, you can do:
arr1.reject!{|o| (arr2 & o[:name]).empty?}
I have an array that contains dates and values. An example of how it might look:
[
{'1/1/2010' => 'aa'},
{'1/1/2010' => 'bb'},
{'1/2/2010' => 'cc'},
{'1/2/2010' => 'dd'},
{'1/3/2010' => 'ee'}
]
Notice that some of the dates repeat. I'm trying to output this in a table format and I only want to show unique dates. So I loop through it with the following code to get my desired output.
prev_date = nil
#reading_schedule.reading_plans.each do |plan|
use_date = nil
if plan.assigned_date != prev_date
use_date = plan.assigned_date
end
prev_date = plan.assigned_date
plan.assigned_date = use_date
end
The resulting table will then look something like this
1/1/2010 aa
bb
1/2/2010 cc
dd
1/3/2010 ee
This work fine but I am new to ruby and was wondering if there was a better way to do this.
Enumerable.group_by is a good starting point:
require 'pp'
asdf = [
{'1/1/2010' => 'aa'},
{'1/1/2010' => 'bb'},
{'1/2/2010' => 'cc'},
{'1/2/2010' => 'dd'},
{'1/3/2010' => 'ee'}
]
pp asdf.group_by { |n| n.keys.first }.map{ |a,b| { a => b.map { |c| c.to_a.last.last } } }
# >> [{"1/1/2010"=>["aa", "bb"]}, {"1/2/2010"=>["cc", "dd"]}, {"1/3/2010"=>["ee"]}]
Which should be a data structure you can bend to your will.
I don't know as though it's better, but you could group the values by date using (e.g.) Enumerable#reduce (requires Ruby >= 1.8.7; before that, you have Enumerable#inject).
arr.reduce({}) { |memo, obj|
obj.each_pair { |key, value|
memo[key] = [] if ! memo.has_key?(key);
memo[key] << value
}
memo
}.sort
=> [["1/1/2010", ["aa", "bb"]], ["1/2/2010", ["cc", "dd"]], ["1/3/2010", ["ee"]]]
You could also use Array#each to similar effect.
This is totally a job for a hash.
Create a hash and use the date as the hashkey and an empty array as the hashvalue.
Then accumulate the values from the original array in the hashvalue array
I have a table with columns 'id', 'resource_id', 'read_time', 'value' where 'value' is a float
What I am trying to accomplish is to return a list of records such that the 'value' of each record is the sum of all the records at a specific 'read_time' but having differing 'resource_id' values.
I am wondering if there is a clever way (ie not looping through all the entries) to accomplish this. Currently I am implementing something along these lines:
#aggregate_meters = []
#res_one_meters = Meter.find(:all, :conditions => ["resource_id = ?", 1])
#res_one_meters.each do |meter|
read_time = meter.read_time
value = meter.value
if res_two_meter = Meter.find(:first, :conditions => ["resource_id = ? AND read_time = ?", 2, read_time ])
value = value + res_two_meter.value
end
aggregate_meter = Meter.new(:read_time => read_time, :value => value, :resource_id => 3)
#aggregate_meters.push(aggregate_meter)
end
Thank you.
ActiveRecord::Calculate is your friend here. Letting you do exactly what you want with one database call. It returns a hash using the unique values in the column used in the group as keys.
Here's the code you wrote, rewritten to use sum.
values = Meter.sum(:value, :group => :read_time)
values.each do |read_time, value|
aggregate_meter = Meter.new(:read_time => read_time, :value => value, :resource_id => 3)
#aggregates_meter.push(aggregate_meter)
end