I'm retrieving data to list and I need to make 2 different intents. "Activities" needs to start "e" intent and rest starts "i" intent.
binding.listview.adapter = MyAdapter(this, personArrayList)
binding.listview.isClickable = true
binding.listview.setOnItemClickListener{
parent, view, position, id ->
val name = name[position]
val activities = activities[position]
val activityTime = activityTime[position]
val description = description[position]
val imageID = imageID[position]
val i = Intent(this, DescriptionActivity::class.java)
val e = Intent(this, ProfileScreen::class.java)
i.putExtra("name", name)
i.putExtra("activityTime", activityTime)
e.putExtra("activities",activities)
i.putExtra("imageID", imageID)
i.putExtra("description", description)
startActivity(i)
}
Maybe second list is an option, but im looking to make this work in one list for now.
I passed a vec parameter into function in rust like this:
pub fn songs(playlist_records: Vec<QueryFavorites>) -> Vec<MusicResponse> {
}
first step I get the ids from playlist_records to execute a query, this is the code:
let ids: Vec<String> = playlist_records
.into_iter()
.map(|item| item.source_id.to_string())
.collect();
when I use the playlist_records second time to fetch the field after get the query result:
for query_song in &results {
let favTime: Vec<QueryFavorites> = playlist_records
.into_iter()
.filter(|item| item.source_id == query_song.source_id)
.collect();
}
it tell me the playlist_records was moved. This is the message:
`playlist_records` moved due to this method call, in previous iteration of loop
I tried to borrow the playlist_records like this:
let ids: Vec<String> = &playlist_records
.into_iter()
.map(|item| item.source_id.to_string())
.collect();
seems did not work, what should I do to reuse the playlist_records?
Change into_iter to use iter, since into_iter consumes the collection while iter iterates by reference and doesn't consume, see more about the difference here:
playground
let ids: Vec<String> = playlist_records
.iter()
.map(|item| item.source_id.to_string())
.collect();
let favTime: Vec<&QueryFavorites> = playlist_records
.iter()
.filter(|item| item.source_id == "someid")
.collect();
which however means your favTime will be of Vec<&QueryFavorites> type if that's fine with you. Otherwise, you can always clone the iterator.
let favTime: Vec<QueryFavorites> = playlist_records
.iter()
.cloned()
.filter(|item| item.source_id == "someid")
.collect();
playground
The goal here is to get the text from a website and append it to the lists so I can then create a dataframe out of it. I managed to make this after lots of Google but now I understand its not the most effective way of doing it, been researching list comprehension but wasnt able to get a successful result.
containers = soup.find_all('td', class_=['TableRecords_EvenLine', 'TableRecords_OddLine'])
dateli = []
descli = []
amtli = []
for container in containers:
date = container.select('div[id*=wtDataMov]')
for element1 in date:
seci1 = element1.get_text()
dateli.append(seci1)
description = container.select('div[id*=wtDescricao]')
for element2 in description:
seci2 = element2.get_text()
descli.append(seci2)
amount = container.select('div[id*=wtValorEur]')
for element3 in amount:
seci3 = element3.get_text()
amtli.append(float(price_str(seci3)))
Ideas? Thanks for you time.
If you want it done using list comprehensions, it would look like this
containers = soup.find_all('td', class_=['TableRecords_EvenLine', 'TableRecords_OddLine'])
dateli = []
descli = []
amtli = []
for container in containers:
dateli += [e.get_text() for e in container.select('div[id*=wtDataMov]')]
descli += [e.get_text() for e in container.select('div[id*=wtDescricao]')]
amtli += [float(price_str(e.get_text())) for e in container.select('div[id*=wtValorEur]')]
This is a continuation of my question at F# List of Union Types. Thanks to the helpful feedback, I was able to create a list of Reports, with Report being either Detail or Summary. Here's the data definition once more:
module Data
type Section = { Header: string;
Lines: string list;
Total: string }
type Detail = { State: string;
Divisions: string list;
Sections: Section list }
type Summary = { State: string;
Office: string;
Sections: Section list }
type Report = Detail of Detail | Summary of Summary
Now that I've got the list of Reports in a variable called reports, I want to iterate over those Report objects and perform operations based on each one. The operations are the same except for the cases of dealing with either Detail.Divisions or Summary.Office. Obviously, I have to handle those differently. But I don't want to duplicate all the code for handling the similar State and Sections of each.
My first (working) idea is something like the following:
for report in reports do
let mutable isDetail = false
let mutable isSummary = false
match report with
| Detail _ -> isDetail <- true
| Summary _ -> isSummary <- true
...
This will give me a way to know when to handle Detail.Divisions rather than Summary.Office. But it doesn't give me an object to work with. I'm still stuck with report, not knowing which it is, Detail or Summary, and also unable to access the attributes. I'd like to convert report to the appropriate Detail or Summary and then use the same code to process either case, with the exception of Detail.Divisions and Summary.Office. Is there a way to do this?
Thanks.
You could do something like this:
for report in reports do
match report with
| Detail { State = s; Sections = l }
| Summary { State = s; Sections = l } ->
// common processing for state and sections (using bound identifiers s and l)
match report with
| Detail { Divisions = l } ->
// unique processing for divisions
| Summary { Office = o } ->
// unique processing for office
The answer by #kvb is probably the approach I would use if I had the data structure you described. However, I think it would make sense to think whether the data types you have are the best possible representation.
The fact that both Detail and Summary share two of the properties (State and Sections) perhaps implies that there is some common part of a Report that is shared regardless of the kind of report (and the report can either add Divisions if it is detailed or just Office if if is summary).
Something like that would be better expressed using the following (Section stays the same, so I did not include it in the snippet):
type ReportInformation =
| Divisions of string list
| Office of string
type Report =
{ State : string;
Sections : Section list
Information : ReportInformation }
If you use this style, you can just access report.State and report.Sections (to do the common part of the processing) and then you can match on report.Information to do the varying part of the processing.
EDIT - In answer to Jeff's comment - if the data structure is already fixed, but the view has changed, you can use F# active patterns to write "adaptor" that provides access to the old data structure using the view that I described above:
let (|Report|) = function
| Detail dt -> dt.State, dt.Sections
| Summary st -> st.State, st.Sections
let (|Divisions|Office|) = function
| Detail dt -> Divisions dt.Divisions
| Summary st -> Office st.Office
The first active pattern always succeeds and extracts the common part. The second allows you to distinguish between the two cases. Then you can write:
let processReport report =
let (Report(state, sections)) = report
// Common processing
match report wiht
| Divisions divs -> // Divisions-specific code
| Office ofc -> // Offices-specific code
This is actually an excellent example of how F# active patterns provide an abstraction that allows you to hide implementation details.
kvb's answer is good, and probably what I would use. But the way you've expressed your problem sounds like you want classic inheritance.
type ReportPart(state, sections) =
member val State = state
member val Sections = sections
type Detail(state, sections, divisions) =
inherit ReportPart(state, sections)
member val Divisions = divisions
type Summary(state, sections, office) =
inherit ReportPart(state, sections)
member val Office = office
Then you can do precisely what you expect:
for report in reports do
match report with
| :? Detail as detail -> //use detail.Divisions
| :? Summary as summary -> //use summary.Office
//use common properties
You can pattern match on the Detail or Summary record in each of the union cases when you match and handle the Divisions or Office value with a separate function e.g.
let blah =
for report in reports do
let out = match report with
| Detail({ State = state; Divisions = divisions; Sections = sections } as d) ->
Detail({ d with Divisions = (handleDivisions divisions) })
| Summary({ State = state; Office = office; Sections = sections } as s) ->
Summary( { s with Office = handleOffice office })
//process out
You can refactor the code to have a utility function for each common field and use nested pattern matching:
let handleReports reports =
reports |> List.iter (function
| Detail {State = s; Sections = ss; Divisions = ds} ->
handleState s
handleSections ss
handleDivisions ds
| Summary {State = s; Sections = ss; Office = o} ->
handleState s
handleSections ss
handleOffice o)
You can also filter Detail and Summary to process them separately in different functions:
let getDetails reports =
List.choose (function Detail d -> Some d | _ -> None) reports
let getSummaries reports =
List.choose (function Summary s -> Some s | _ -> None) reports
For example i have erlang record:
-record(state, {clients
}).
Can i make from clients field list?
That I could keep in client filed as in normal list? And how can i add some values in this list?
Thank you.
Maybe you mean something like:
-module(reclist).
-export([empty_state/0, some_state/0,
add_client/1, del_client/1,
get_clients/1]).
-record(state,
{
clients = [] ::[pos_integer()],
dbname ::char()
}).
empty_state() ->
#state{}.
some_state() ->
#state{
clients = [1,2,3],
dbname = "QA"}.
del_client(Client) ->
S = some_state(),
C = S#state.clients,
S#state{clients = lists:delete(Client, C)}.
add_client(Client) ->
S = some_state(),
C = S#state.clients,
S#state{clients = [Client|C]}.
get_clients(#state{clients = C, dbname = _D}) ->
C.
Test:
1> reclist:empty_state().
{state,[],undefined}
2> reclist:some_state().
{state,[1,2,3],"QA"}
3> reclist:add_client(4).
{state,[4,1,2,3],"QA"}
4> reclist:del_client(2).
{state,[1,3],"QA"}
::[pos_integer()] means that the type of the field is a list of positive integer values, starting from 1; it's the hint for the analysis tool dialyzer, when it performs type checking.
Erlang also allows you use pattern matching on records:
5> reclist:get_clients(reclist:some_state()).
[1,2,3]
Further reading:
Records
Types and Function Specifications
dialyzer(1)
#JUST MY correct OPINION's answer made me remember that I love how Haskell goes about getting the values of the fields in the data type.
Here's a definition of a data type, stolen from Learn You a Haskell for Great Good!, which leverages record syntax:
data Car = Car {company :: String
,model :: String
,year :: Int
} deriving (Show)
It creates functions company, model and year, that lookup fields in the data type. We first make a new car:
ghci> Car "Toyota" "Supra" 2005
Car {company = "Toyota", model = "Supra", year = 2005}
Or, using record syntax (the order of fields doesn't matter):
ghci> Car {model = "Supra", year = 2005, company = "Toyota"}
Car {company = "Toyota", model = "Supra", year = 2005}
ghci> let supra = Car {model = "Supra", year = 2005, company = "Toyota"}
ghci> year supra
2005
We can even use pattern matching:
ghci> let (Car {company = c, model = m, year = y}) = supra
ghci> "This " ++ c ++ " " ++ m ++ " was made in " ++ show y
"This Toyota Supra was made in 2005"
I remember there were attempts to implement something similar to Haskell's record syntax in Erlang, but not sure if they were successful.
Some posts, concerning these attempts:
In Response to "What Sucks About Erlang"
Geeking out with Lisp Flavoured Erlang. However I would ignore parameterized modules here.
It seems that LFE uses macros, which are similar to what provides Scheme (Racket, for instance), when you want to create a new value of some structure:
> (define-struct car (company model year))
> (define supra (make-car "Toyota" "Supra" 2005))
> (car-model supra)
"Supra"
I hope we'll have something close to Haskell record syntax in the future, that would be really practically useful and handy.
Yasir's answer is the correct one, but I'm going to show you WHY it works the way it works so you can understand records a bit better.
Records in Erlang are a hack (and a pretty ugly one). Using the record definition from Yasir's answer...
-record(state,
{
clients = [] ::[pos_integer()],
dbname ::char()
}).
...when you instantiate this with #state{} (as Yasir did in empty_state/0 function), what you really get back is this:
{state, [], undefined}
That is to say your "record" is just a tuple tagged with the name of the record (state in this case) followed by the record's contents. Inside BEAM itself there is no record. It's just another tuple with Erlang data types contained within it. This is the key to understanding how things work (and the limitations of records to boot).
Now when Yasir did this...
add_client(Client) ->
S = some_state(),
C = S#state.clients,
S#state{clients = [Client|C]}.
...the S#state.clients bit translates into code internally that looks like element(2,S). You're using, in other words, standard tuple manipulation functions. S#state.clients is just a symbolic way of saying the same thing, but in a way that lets you know what element 2 actually is. It's syntactic saccharine that's an improvement over keeping track of individual fields in your tuples in an error-prone way.
Now for that last S#state{clients = [Client|C]} bit, I'm not absolutely positive as to what code is generated behind the scenes, but it is likely just straightforward stuff that does the equivalent of {state, [Client|C], element(3,S)}. It:
tags a new tuple with the name of the record (provided as #state),
copies the elements from S (dictated by the S# portion),
except for the clients piece overridden by {clients = [Client|C]}.
All of this magic is done via a preprocessing hack behind the scenes.
Understanding how records work behind the scenes is beneficial both for understanding code written using records as well as for understanding how to use them yourself (not to mention understanding why things that seem to "make sense" don't work with records -- because they don't actually exist down in the abstract machine...yet).
If you are only adding or removing single items from the clients list in the state you could cut down on typing with a macro.
-record(state, {clients = [] }).
-define(AddClientToState(Client,State),
State#state{clients = lists:append([Client], State#state.clients) } ).
-define(RemoveClientFromState(Client,State),
State#state{clients = lists:delete(Client, State#state.clients) } ).
Here is a test escript that demonstrates:
#!/usr/bin/env escript
-record(state, {clients = [] }).
-define(AddClientToState(Client,State),
State#state{clients = lists:append([Client], State#state.clients)} ).
-define(RemoveClientFromState(Client,State),
State#state{clients = lists:delete(Client, State#state.clients)} ).
main(_) ->
%Start with a state with a empty list of clients.
State0 = #state{},
io:format("Empty State: ~p~n",[State0]),
%Add foo to the list
State1 = ?AddClientToState(foo,State0),
io:format("State after adding foo: ~p~n",[State1]),
%Add bar to the list.
State2 = ?AddClientToState(bar,State1),
io:format("State after adding bar: ~p~n",[State2]),
%Add baz to the list.
State3 = ?AddClientToState(baz,State2),
io:format("State after adding baz: ~p~n",[State3]),
%Remove bar from the list.
State4 = ?RemoveClientFromState(bar,State3),
io:format("State after removing bar: ~p~n",[State4]).
Result:
Empty State: {state,[]}
State after adding foo: {state,[foo]}
State after adding bar: {state,[bar,foo]}
State after adding baz: {state,[baz,bar,foo]}
State after removing bar: {state,[baz,foo]}