I have an array of objects, each of which has the property :cow either set to false or true:
animals = [
{
id: 1,
cow: true
},
{
id: 2,
cow: true
},
{
id: 3,
cow: true
},
{
id: 4,
cow: false
},
{
id: 5,
cow: false
}
]
I need to select all members of the array that pass a condition without iterating through every element of the array.
Is it possible?
I tried:
notCows = animals.reject { |a| !a[:cow] }
notCows = animals[0, 1, 2]
which doesn't work.
No, this is impossible. In order to find all elements that satisfy a certain condition, you need to look at all elements to see whether they satisfy that condition. It is simply logically not possible to find all elements of a collection without iterating through all elements of the collection.
You were almost there, use Enumerable#select (which scans the all the member of the collection, by the way):
animals.select { |animal| animal[:cow] }
#=> [{:id=>1, :cow=>true}, {:id=>2, :cow=>true}, {:id=>3, :cow=>true}]
Or the opposite:
animals.select { |animal| !animal[:cow] }
#=> [{:id=>4, :cow=>false}, {:id=>5, :cow=>false}]
The returned results are still Ruby objects: Arrays of Hashes.
As alternative you can group by status (Enumerable#group_by):
animals.group_by { |a| a[:cow] }
#=> {true=>[{:id=>1, :cow=>true}, {:id=>2, :cow=>true}, {:id=>3, :cow=>true}], false=>[{:id=>4, :cow=>false}, {:id=>5, :cow=>false}]}
Related
I am building a Rails 5.2 app.
In this app I am working with statistics.
I generate two objects:
{
"total_project": {
"website": 1,
"google": 1,
"instagram": 1
}
}
And this:
{
"total_leads": {
"website": 1,
"google": 2,
"client_referral": 1
}
}
I need to merge these two objects into one single objects that increases the count. The desired result is:
{
"total_both": {
"website": 2,
"google": 3,
"instagram": 1,
"client_referral": 1
}
}
I tried this and it technically works, it merges the objects but the count is not updated:
#total_project = array_projects.group_by { |d| d[:entity_type] }.transform_values(&:count).symbolize_keys
#total_leads = array_leads.group_by { |d| d[:entity_type] }.transform_values(&:count).symbolize_keys
#total_sources = merged.merge **#total_project, **#total_leads
Please note that the attributes (sources) are dynamic from the database so I cannot hard code anything. The user can add their own sources.
#total_sources = #total_project.merge(#total_leads) do |key, ts_value, tp_value|
ts_value + tp_value
end
If there can be more than 2 sources, put everything in an array and do.
#total_sources = source_array.reduce do |accumulator, next_source|
accumulator.merge(next_source) { |key, v1, v2| v1 + v2 }
end
You may compute the desired result as follows.
arr = [{ "total_project": { "website": 1, "google": 1, "instagram": 1 } },
{ "total_leads": { "website": 1, "google": 2, "client_referral": 1 } }]
{ "total_both" => arr.flat_map(&:values)
.reduce { |h,g| h.merge(g) { |_,o,n| o+n } } }
#=> {"total_both"=>{:website=>2, :google=>3, :instagram=>1, :client_referral=>1}}
Note that
arr.flat_map(&:values)
#=> [{:website=>1, :google=>1, :instagram=>1},
# {:website=>1, :google=>2, :client_referral=>1}]
Had I used Array#map this would have been
arr.map(&:values)
#=> [[{:website=>1, :google=>1, :instagram=>1}],
# [{:website=>1, :google=>2, :client_referral=>1}]]
See Enumerable#flat_map, Enumerable#reduce and the form of Hash#merge that takes a block (here { |_,o,n| o+n }) which returns the values of keys that are present in both hashes being merged. See the doc for merge for definitions of the three block variables (here _, o and n). I have named the first block variable (holding the common key) _ to signal to the reader that it is not used in the block calculation (a common Ruby convention).
I am trying to convert one of my array into some format where it can convert itself into table format.
I have an array which is:
[
{
id: 1,
Revenue_Account: "Revenue Receipt",
Amount: 59567,
Year: "2012-13",
created_at: "2018-08-21T06:30:17.000Z",
updated_at: "2018-08-21T06:30:17.000Z"
},
{
id: 2,
Revenue_Account: "Revenue Expenditure ",
Amount: 54466,
Year: "2012-13",
created_at: "2018-08-21T06:30:17.000Z",
updated_at: "2018-08-21T06:30:17.000Z"
},
...
]
Full code of my array link to my actual array
I want this data to be converted into this format:
data: [
{
id: 1,
Sector: "Revenue Receipt",
2012-13: 59567,
2013-14: 68919,
2014-15: 72570,
2015-16: 96123,
2016-17: 105585,
2017-18_BE: 137158,
},
{
id: 2,
Sector: "Revenue Expenditure",
2012-13: 59567,
2013-14: 68919,
2014-15: 72570,
2015-16: 96123,
2016-17: 105585,
2017-18_BE: 137158,
},
....
]
I am using this code to group my array:
group = b.group_by{|data| data[:Revenue_Account]}
this is grouping my data as I am expecting in order to achieve my goal I am trying this code.
group = b.group_by{|data| data[:Revenue_Account]}
du = []
group.each do |i|
du.push({Sector:i[0]})
end
This is giving me Sector wise result how can I add year in my code.
You can't have a single id in there because you're grouping up many entries with different ids, but this is how you'd get the array in the format you're asking for:
grouped = {}
b.each do |x|
grouped[x[:Revenue_Account]] ||= {}
grouped[x[:Revenue_Account]][:Sector] = x[:Revenue_Account]
grouped[x[:Revenue_Account]][x[:Year]] = x[:Amount]
end
return {data: grouped.values}
Which gets you:
{
:data=>[
{
:Sector=>"Revenue Receipt",
"2012-13"=>59567,
"2013-14"=>68919,
"2014-15"=>78417,
"2015-16"=>96123,
"2016-17"=>105585,
"2017-18_BE"=>137158
},
{
:Sector=>"Revenue Expenditure ",
"2012-13"=>54466,
"2013-14"=>62477,
"2014-15"=>72570,
"2015-16"=>83616,
"2016-17"=>94765,
"2017-18_BE"=>122603
},
]
}
We build a new hash by looping through the original hash and creating hash keys if they don't exist. Then we start assigning values as you want them to be in the output. On each iteration, we're creating a new key in this hash for the Revenue_Account value if its the first time we've seen it. Then we assign that particular Revenue_Account's Date and Amount to the output. So for value 'Revenue Receipt' it looks like this:
Grouped hash starts off as empty
On first iteration, we see that group["Revenue Receipt"] is nil, so we initialize it with an empty hash via ||= (assign if nil)
We then assign :Sector => "Revenue Receipt" and this entry's Year and Amount, "2012-13" => 59567
Our grouped hash looks like: {"Revenue Receipt" => {:Sector => "Revenue Receipt", "2012-13" => 59567}
On the next iteration we see that group["Revenue Receipt"] is not nil, so ||= does not override it with an empty hash
We then assign :Sector => "Revenue Receipt" and this entry's Year and Amount, "2012-14" => 68919, which adds a new key/value to the existing hash
Our grouped hash now looks like: {"Revenue Receipt" => {:Sector => "Revenue Receipt", "2012-13" => 59567, "2012-14" => 68919}
After we parse the entire array, we now have a hash that has a key of the Revenue_Account, and values which look like the hash output you're expecting.
We discard the key and return only the hash values, which gets you the final output.
Another option, directly manipulating the array.
array_of_data = array
.each { |h| h[:Sector] = h.delete(:Revenue_Account) }
.each { |h| h[h[:Year]] = h[:Amount]}
.each { |h| h.delete_if{ |k, _| k == :created_at || k == :updated_at || k == :id || k == :Year || k == :Amount} }
.group_by { |h| h[:Sector] }
.values.map { |a| a.inject(:merge) }
Then just:
h = {}
h[:data] = array_of_data
To understand what happens along the code, just ad line by line outputting the result, like:
p array
.each { |h| h[:Sector] = h.delete(:Revenue_Account) }
Then:
p array
.each { |h| h[:Sector] = h.delete(:Revenue_Account) }
.each { |h| h[h[:Year]] = h[:Amount]}
Etcetera...
To understand .inject(:merge), see here Rails mapping array of hashes onto single hash
I have an array and it has many columns and I want to change one value of my one column.
My array is:
[
{
id: 1,
Districts: "Lakhisarai",
Area: 15.87,
Production: 67.77,
Productivity: 4271,
Year: 2015,
Area_Colour: "Red",
Production_Colour: "Orange",
Productivity_Colour: "Dark_Green",
created_at: "2018-07-24T11:24:13.000Z",
updated_at: "2018-07-24T11:24:13.000Z"
},
{
id: 29,
Districts: "Begusarai",
Area: 18.53,
Production: 29.35,
Productivity: 1584,
Year: 2015,
Area_Colour: "Red",
Production_Colour: "Red",
Productivity_Colour: "Orange",
created_at: "2018-07-24T11:24:13.000Z",
updated_at: "2018-07-24T11:24:13.000Z"
},
...
]
This is my sample array and I want my Productivity to be divided by 100 for that I am using one empty array and pushing these hashes to my array like:
j = []
b.map do |k|
if k.Productivity
u = k.Productivity/100
j.push({id: k.id, Productivity: u })
else
j.push({id: k.id, Productivity: k.Productivity })
end
Is there any simple way where I can generate this kind of array and reflect my changes to to one column. Is there any way where I don't need to push name of column one by one in push method.
I want to generate exact same array with one modification in productivity
let's say your array is e, then:
e.each { |item| item[:Productivity] = item[:Productivity]/100}
Example:
e = [{p: 12, d: 13}, {p:14, d:70}]
e.each { |item| item[:p] = item[:p]/10}
output: [{:p=>1, :d=>13}, {:p=>1, :d=>70}]
You could take help of map method here to create a new array from your original array, but with the mentioned changes.
ary.map do |elem|
h = elem.slice(:id)
h[:productivity] = elem[:Productivity] / 100 if elem[:Productivity]
h
end
=> [{:id=>1, :productivity=>42}, {:id=>29, :productivity=>15}]
Note, Hash#slice returns a new hash with only the key-value pairs for the keys passed in argument e.g. here, it returns { id: 1 } for first element.
Also, we are assigning the calculated productivity to the output only when it is set on original hash. Hence, the if condition there.
I have 2 apples:
{
id: 1,
rotten: true,
branch_on_tree: nil,
type: "red delicious"
},
{
id: 2,
rotten: nil,
branch_on_tree: 5,
type: "red delicious"
}
They are duplicate apples for red delicious. How do I merge the records together and then delete the one with missing data? Is there a convenient way to do this?
Note: There might be like 10 duplicates. I don't want any null values in my final record. Non-null values take precedence.
Not very convinient way but it will work
assuming apples is an array:
[
{
id: 1,
rotten: true,
branch_on_tree: nil,
type: "red delicious"
},
# ...
]
that can come from:
apples = Apple.where(type: "red delicious")
apples_attrs = apples.map(&:attributes)
Then,
apple_attrs = apples_attrs.reduce do |apple, next_apple|
apple.merge(next_apple) do |_, old_value, new_value|
old_value || new_value
end
end
apples.destroy_all
Apple.create(apple_attrs)
You might want to check this guide https://apidock.com/ruby/Hash/merge
Assuming type always has some value, you can use DISTINCT with where clause. The below should work
Apple.where('rotten IS NOT NULL AND branch_on_tree IS NOT NULL').select('DISTINCT ON (type) rotten,branch_on_tree,type').take
I'm looking for some advice on how to properly merge some key/value pairs into a separate database entry and summing their values.
I have a Task which has a Vendor_Upload which has many Vendor_Shipping_Logs which has many Vendor_Shipping_Log_Products. I'm not sure if the deep nesting makes a difference, but the important values to look at here are the Item_ID and Quantity.
This is currently how the parameters are spit out:
Parameters: {
"task"=>{
"task_type"=>"Vendor Upload",
"vendor_upload_attributes"=>{
"upload_type"=>"Warranty Orders",
"vendor_shipping_logs_attributes"=>{
"1490674883303"=>{
"guest_name"=>"Martin Crane",
"order_number"=>"33101",
"vendor_shipping_log_products_attributes"=>{
"1490675774108"=>{
"item_id"=>"211",
"quantity"=>"3"
},
"1490675775147"=>{
"item_id"=>"213",
"quantity"=>"6"
}
}
},
"1490674884454"=>{
"guest_name"=>"Frasier Crane",
"order_number"=>"33102",
"vendor_shipping_log_products_attributes"=>{
"1490675808026"=>{
"item_id"=>"214",
"quantity"=>"10"
},
"1490675808744"=>{
"item_id"=>"213",
"quantity"=>"1"
}
}
},
"1490674885293"=>{
"guest_name"=>"Niles Crane",
"order_number"=>"33103",
"vendor_shipping_log_products_attributes"=>{
"1490675837184"=>{
"item_id"=>"211",
"quantity"=>"3"
}
}
},
"1490674886373"=>{
"guest_name"=>"Daphne Moon",
"order_number"=>"33104",
"vendor_shipping_log_products_attributes"=>{
"1490675852950"=>{
"item_id"=>"213",
"quantity"=>"8"
},
"1490675853845"=>{
"item_id"=>"214",
"quantity"=>"11"
}
}
}
}
}
}
}
Upon submission I want to merge each unique Vendor_Shipping_Log_Products Item_IDs and sum their quantities into a new Stockmovement_Batch as a nested Stockmovement to keep my inventories up to date.
See example patameters here of what I would like the output to look like:
Parameters: {
"stockmovement_batch"=>{
"stockmovement_type"=>"Ecomm Order",
"stockmovements_attributes"=>{
"1490676054881"=>{
"item_id"=>"211",
"adjust_quantity"=>"-6"
},
"1490676055897"=>{
"item_id"=>"213",
"adjust_quantity"=>"-15"
},
"1490676057616"=>{
"item_id"=>"214",
"adjust_quantity"=>"-21"
}
}
}
}
Is this something I can do all in one simple go, or do I have to stick with doing each process in a separate form?
First you need to separate out the values you want to iterate through:
data = params.require("task")
.require("vendor_upload_attributes")
.require("vendor_shipping_logs_attributes")
Then pull the vendor_shipping_log_products_attributes and flatten it to an array of hashes:
logs = data.values.map do |h|
h["vendor_shipping_log_products_attributes"].values
end.flatten
# => [{"item_id"=>"211", "quantity"=>"3"}, {"item_id"=>"213", "quantity"=>"6"}, {"item_id"=>"214", "quantity"=>"10"}, {"item_id"=>"213", "quantity"=>"1"}, {"item_id"=>"211", "quantity"=>"3"}, {"item_id"=>"213", "quantity"=>"8"}, {"item_id"=>"214", "quantity"=>"11"}]
Then we merge the data by creating a intermediary hash where we use the item_id as keys.
stockmovements = logs.each_with_object({}) do |hash, memo|
id = hash["item_id"]
memo[id] ||= []
memo[id].push(hash["quantity"].to_i)
end
# => {"211"=>[3, 3], "213"=>[6, 1, 8], "214"=>[10, 11]}
We then can then map the result and sum the values:
stockmovements.map do |(k,v)|
{
item_id: k,
adjust_quantity: 0 - v.sum
}
end
# => [{:item_id=>"211", :adjust_quantity=>-6}, {:item_id=>"213", :adjust_quantity=>-15}, {:item_id=>"214", :adjust_quantity=>-21}]