I want to know how to use Observable.
What I want to do is duplicate deletion. The following sample 1 can be moved, but what I want to do is not this format, but how to cook when preparing an array in advance.
orgLayerDistinct(allList: LabelMasterExt[]) {
// Observable.of( allList ).distinct( );
// [sample 1] このサンプルは動くが好みの形式ではない。
// [sample 1] This sample works, but it's not a form of favorite.
Observable.of<Person>(
{ age: 4, name: 'Foo'},
{ age: 7, name: 'Bar'},
{ age: 5, name: 'Foo'},
{ age: 6, name: 'Foo'})
.distinct((p: Person) => p.name)
.subscribe(x => console.log(x));
// [sample 2 experimental] 配列を用意してある前提で利用したい。
// [sample 2 experimental] I would like to use an array on the assumption that it is prepared.
const persons: Person[] = [];
persons.push({ age: 4, name: 'Foo'});
persons.push({ age: 7, name: 'Bar'});
persons.push({ age: 5, name: 'Foo'});
persons.push({ age: 6, name: 'Foo'});
Observable.of<Person[]>(persons)
.distinct((p: Person) => p.name)
.subscribe(x => console.log(x));
}
[sample 2 experimental]
However, this gives the following error.
The type argument for type parameter 'T' cannot be inferred from the usage.
Consider specifying the type arguments explicitly.
Type argument candidate 'Person[]' is not a valid type argument
because it is not a supertype of candidate 'Person'.
Property 'includes' is missing in type 'Person'.
Is there any good plan?
You can either use Observable.from<Person>(array) or Observable.of<Person>(...array).
The problem your second example has is that Observable.of<Person[]>()s elements are arrays of Person, but the .distinct() is expecting an input of the Person type.
Related
I'm trying to to group the values from an observable into an array of n size, to be able to batch send these to a service to improve the overall performance.
The thing is that I want to make sure that when the items left are less then n, they will be still be passed down the chain after a certain timeout.
I'm trying to rewrite the C# solution from
https://stackoverflow.com/a/22873833/2157455
in Javascript.
The main problem is that in Rx.Js lots of methods have been deprecated and it's hard to find the new functions.
var people = new List<(string name, int age)>
{
("Sue", 25 ),
("Joe", 30 ),
("Frank", 25 ),
("Sarah", 35 ),
("John", 37)
}.ToObservable();
var buffers = people
.GroupByUntil(
// yes. yes. all items belong to the same group.
x => true,
g => Observable.Amb(
// close the group after 5 seconds of inactivity
g.Throttle(TimeSpan.FromSeconds(5)),
// close the group after 10 items
g.Skip(1)
))
// Turn those groups into buffers
.SelectMany(x => x.ToArray());
I could get this far, but I can't find the replacement for groupByUntil. And I'm not sure what's the selectMany operator in Rx.Js, probably toArray().
Most examples I find are using deprecated or non-exising functions.
I'm using rxjs 7.8.0
The syntax does not help as well, using the pipe all the time makes the code difficult to read in my opinion.
const people = [
{ name: 'Sue', age: 25 },
{ name: 'Joe', age: 30 },
{ name: 'Frank', age: 25 },
{ name: 'Sarah', age: 35 },
{ name: 'John', age: 37 }
];
const source = from(people);
const example = source.pipe(
groupBy(person => true),
mergeMap(group => group.pipe(
raceWith(
group.pipe(throttle(() => interval(1000))),
group.pipe(skip(2))
),
toArray()
)));
example.forEach(x => console.log(x.length));
I'm getting all 5, instead of two arrays, one with 3 the other with 2.
Perhaps there is a better way to write it in js, but I can;t see the replacement for groupByUntil.
Thanks.
bufferTime is probably what you are looking for
One of its signature is :
bufferTime(bufferTimeSpan: number, bufferCreationInterval: number, maxBufferSize: number, scheduler?: SchedulerLike): OperatorFunction<T, T[]>
so with bufferTime(1000, null, 2) you get a buffered of length=2 or every 1s.
systems:
- name: Fred
country: DE
- name: Wilma
country: US
- name: Pebbles
country: DE
- name: Dino
country: US
---
# Systems
Countries: {{ page.systems | join(",", "country") }}
I am trying to create a GitBook page with a list of items containing no duplicates. I.e I would want to apply a 'unique' filter or 'distinct' filter in my Nunjucks template for the page. The template needs to process the page variables (YAML). The above template generates the output:
Countries: DE,US,DE,US
I would like it to produce the output
Countries: DE,US
How could I achive that? (Given that 'unique' filter is not supported with Nunjucks.)
You can extend your Nunjucks through Custom filter
const nunjucks = require('nunjucks');
const env = new nunjucks.Environment(/* loaders etc... */);
env.addFilter('unique', arr => arr instanceof Array && arr.filter((e, i, arr) => arr.indexOf(e) == i) || arr);
let out = env.renderString(`{{[1, 2, 3, 2] | unique }}`);
console.log(out);
Very similar to these two CouchDB questions: 3311225 and 8924793, except that these approaches don't allow partial matching. Having e.g. these entries:
[{_id: 1, status: 'NEW', name: 'a'},
{_id: 2, status: 'NEW', name: 'aab'},
{_id: 3, status: 'NEW', name: 'ab'},
{_id: 4, status: 'NEW', name: 'aaa'},
{_id: 5, status: 'NEW', name: 'aa'}]
and key
[status, name, _id]
There seems to be no way to
filter these entries by status (full string match) and name (partial string match ~ startsWith)
order them by id
paginate them
because of the partial string match on name. The high value unicode character \uffff that allows this partial match also causes to ignore the _id part of the key, meaning the resulting entries are not sorted by _id, but rather by status and name.
var status = 'NEW';
var name = 'aa'
var query = {
startkey: [status, name],
endkey: [status, name + '\uffff', {}],
skip: 0,
limit: 10
};
results in
[{_id: 5, status: 'NEW', name: 'aa'},
{_id: 4, status: 'NEW', name: 'aaa'},
{_id: 2, status: 'NEW', name: 'aab'}]
There is no option to sort in memory, as this would only sort the individual pages, and not the entire data set. Any ideas about this?
I am trying to filter ActiveRecord_AssociationRelations to be unique by parent id.
So, I'd like a list like this:
[#<Message id: 25, posted_by_id: 3, posted_at: "2014-10-30 06:02:47", parent_id: 20, content: "This is a comment", created_at: "2014-10-30 06:02:47", updated_at: "2014-10-30 06:02:47">,
#<Message id: 23, posted_by_id: 3, posted_at: "2014-10-28 16:11:02", parent_id: 20, content: "This is another comment", created_at: "2014-10-28 16:11:02", updated_at: "2014-10-28 16:11:02">]}
to return this:
[#<Message id: 25, posted_by_id: 3, posted_at: "2014-10-30 06:02:47", parent_id: 20, content: "This is a comment", created_at: "2014-10-30 06:02:47", updated_at: "2014-10-30 06:02:47">]
I've tried various techniques including:
#messages.uniq(&:parent_id) # returns the same list (with duplicate parent_ids)
#messages.select(:parent_id).distinct # returns [#<Message id: nil, parent_id: 20>]
and uniq_by has been removed from Rails 4.1.
Have you tried
group(:parent_id)
It sounds to me like that is what you are after. This does return the first entry with the given parent_id. If you want the last entry you will have to reorder the result in a subquery and then use the group.
For me in Rails 3.2 & Postgresql, Foo.group(:bar) works on simple queries but gives me an error if I have any where clauses on there, for instance
irb> Message.where(receiver_id: 434).group(:sender_id)
=> PG::GroupingError: ERROR: column "messages.id" must appear in the
GROUP BY clause or be used in an aggregate function
I ended up specifying an SQL 'DISTINCT ON' clause to select. In a Message class I have the following scope:
scope :latest_from_each_sender, -> { order("sender_id ASC, created_at DESC").select('DISTINCT ON ("sender_id") *') }
Usage:
irb> Message.where(receiver_id: 434).latest_from_each_sender
Given this array in Ruby:
myarray = [name: "John", age: 35]
How do I refer to the age?
I tried myarray[:age] but got an error can't convert Symbol into Integer
Update:
I was trying to simplify my question by extracting what I thought my problem is. I may not understand completely.
I'm experimenting with Dashing and trying to send a number to a meter widget. I've created a variable, 'response_raw' and am trying to send it in the third send event. Here's my code:
SCHEDULER.every '1m', :first_in => 0 do
# Get checks
url = "https://#{CGI::escape user}:#{CGI::escape password}#api.pingdom.com/api/2.0/checks"
`enter code here`response = RestClient.get(url, {"App-Key" => api_key})
response = JSON.parse(response.body, :symbolize_names => true)
if response[:checks]
checks = response[:checks].map { |check|
if check[:status] == 'up'
state = 'up'
last_response_time = "#{check[:lastresponsetime]}ms"
response_raw = check[:lastresponsetime]
else
state = 'down'
last_response_time = "DOWN"
response_raw = 0
end
{ name: check[:name], state: state, lastRepsonseTime: last_response_time, pt: response_raw }
}
else
checks = [name: "pingdom", state: "down", lastRepsonseTime: "-", pt: 0]
end
checks.sort_by { |check| check['name'] }
send_event('pingdom', { checks: checks })
send_event('pingdom-meter', { value: checks[:pt] })
end
In CoffeeScript [name: "John", age: 35] is an array containing single object with two properties (name and age).
Here is how it'll look in plain JavaScript:
myarray = [
{
name: "John",
age: 35
}
];
So, answering your question, to access an age you should take the first element of an array and then reference an age property:
myarray[0].age
or
myarray[0]['age']
But, judging from your question, your're probably using wrong data structure. Why don't you want to use a plain object instead of an array?
person = name: "John", age: 35
console.log "#{person.name}'s age is #{person.age}"
Update
It looks like your question is actually about Ruby and not about CoffeeScript. Though, my answer will remain the same.
To access an age you should take the first element of an array and then reference an age property:
myarray[0][:age]
Since myarray is an array, Ruby expects an integer index, but you're giving it symbol :age instead.
I finally figured it out with Leonid's help. Thank you.
I changed:
send_event('pingdom-meter', { value: checks[:pt] })
to
send_event('pingdom-meter', { value: checks[0][:pt] })