Please tell me how in such a data structure (simplified for better understanding) to bring all the children of the entity into one list:
fun main() {
val listOfEntities = listOf(
Entity(
name = "John",
entities = listOf(
Entity(
name = "Adam",
entities = listOf()
),
Entity(
name = "Ivan",
entities = listOf(
Entity(
name = "Henry",
entities = listOf(
Entity(
name = "Kate",
entities = listOf(
Entity(
name = "Bob",
entities = listOf()
)
)
)
)
)
)
)
)
)
)
val result = listOfEntities.flatMap { it.entities }.map { it.name }
println(result)
}
data class Entity(
val name: String,
val entities: List<Entity>
)
I expect to see following result:
[John, Adam, Ivan, Henry, Kate, Bob]
I try to use flatMap, but it did not lead to the expected result.
Thank you in advance!
You can traverse the tree of Entities recursively like this:
fun List<Entity>.flattenEntities(): List<Entity> =
this + flatMap { it.entities.flattenEntities() }
Then you can call
val result = listOfEntities.flattenEntities().map { it.name }
to obtain the desired result.
You could do it like this
fun List<Entity>.flatten(): List<String> {
return flatMap { listOf(it.name) + it.entities.flatten()}
}
and then
val result = listOfEntities.flatten()
Related
I have a project that needs me to remove items if one of the properties of the item I'm trying to find within the list is true. Just so it's easier understand the project I am pasting all code needed to understand it below.
fun main() {
val acct1 = AccountId(72)
val calendars = mutableListOf<CalendarDrawerCalendarItem>()
val calendars2 = mutableListOf<CalendarDrawerCalendarItem>()
calendars.add(CalendarDrawerCalendarItem(CalendarDescriptor(acct1, CalendarId(acct1, 3),"toast", true)))
calendars.add(CalendarDrawerCalendarItem(CalendarDescriptor(acct1, CalendarId(acct1, 4), "chicken", false)))
calendars.add(CalendarDrawerCalendarItem(CalendarDescriptor(acct1, CalendarId(acct1, 5), "pizza", true)))
calendars2.add(CalendarDrawerCalendarItem(CalendarDescriptor(acct1, CalendarId(acct1, 1), "bagel", true)))
// These are example calls to collapse
collapse(calendars, CalendarDrawerGroupItem(true, CalendarGroupDescriptor( acct1, "My Calendars")))
collapse(calendars2, CalendarDrawerGroupItem(false, CalendarGroupDescriptor(acct1, "Group Calendars")))
}
fun collapse(calendars: List<CalendarDrawerListItem>, group: CalendarDrawerGroupItem): List<CalendarDrawerListItem> {
val collapsedResults = mutableListOf<CalendarDrawerListItem>()
val findGroupGiven = group
collapsedResults.addAll(calendars)
if (collapsedResults.contains(findGroupGiven)) {
group.collapsed = true
// logic for deleting items here
}
return collapsedResults
}
I'll also put the classes so you can see how they're defined
data class AccountId(
val accountId: Int
)
data class CalendarId(
val accountId: AccountId,
val calendarId: Int)
data class CalendarDescriptor(
val accountId: AccountId,
val calendarId: CalendarId,
val name: String,
val isGroupCalendar: Boolean
)
data class CalendarGroupDescriptor(
val accountId: AccountId,
val name: String,
)
sealed class CalendarDrawerListItem
data class CalendarDrawerGroupItem(var collapsed: Boolean, val groupDescriptor: CalendarGroupDescriptor) : CalendarDrawerListItem()
data class CalendarDrawerCalendarItem(val calendarDescriptor: CalendarDescriptor) : CalendarDrawerListItem()
The first step I have done is I must find the given group from the group variable, within calendars. (I did this with the contains() method). Next when I find the group I have to set its collapsed variable to true and any CalendarDrawerCalendarItems after it have to be deleted.
The input will look something like (the exact numbers and values are not the important part):
Input:
calendars:
CDGroupItem(collapsed = false, groupDescriptor = GroupDescriptor(accountId = 1, name = "My calendars"))
CDCalendarItem(calendarDescriptor = CalendarDescriptor(accountId = 1, calendarId = 1, isGroup = false))
CDCalendarItem(calendarDescriptor = CalendarDescriptor(accountId = 1, calendarId = 2, isGroup = false))
CDCalendarItem(calendarDescriptor = CalendarDescriptor(accountId = 1, calendarId = 3, isGroup = false))
CDGroupItem(collapsed = false, groupDescriptor = GroupDescriptor(accountId = 1, name = "Group calendars"))
CDCalendarItem(calendarDescriptor = CalendarDescriptor(accountId = 1, calendarId = 4, isGroup = true))
CDCalendarItem(calendarDescriptor = CalendarDescriptor(accountId = 1, calendarId = 5, isGroup = true))
group: CDGroupItem(collapsed = false, groupDescriptor = GroupDescriptor(accountId = 1, name = "My calendars"))
The output should look something like this:
Output:
CDGroupItem(collapsed = true, groupDescriptor = GroupDescriptor(accountId = 1, name = "My calendars"))
CDGroupItem(collapsed = false, groupDescriptor = GroupDescriptor(accountId = 1, name = "Group calendars"))
CDCalendarItem(calendarDescriptor = CalendarDescriptor(accountId = 1, calendarId = 4, isGroup = true))
CDCalendarItem(calendarDescriptor = CalendarDescriptor(accountId = 1, calendarId = 5, isGroup = true))
Any group item that has its collapsed boolean set to true should have all calendar items deleted after it since its collapsed is set to true. Again the names and numbers are not super important. The collapsed bool is. How can I do this without hardcoding or using indicies?
Your example code doesn't use that input and output as-is so I can only give you a general example, but you could use a fold:
val result = calendars.fold(mutableListOf<CalendarDrawerListItem>()) { items, current ->
// basically 'is there a last item stored, and is it a group item, and is it collapsed'
val lastStoredIsCollapsed =
(items.lastOrNull() as? CalendarDrawerGroupItem)?.collapsed == true
if (current is CalendarDrawerCalendarItem && lastStoredIsCollapsed) items
else items.apply { add(current) }
}
It basically pipes out each item into a list, but if the last one it stored is a CalendarDrawerGroupItem with collapsed set to true, it drops drawer items. If the last one is a non-collapsed group item, it can store a drawer item, and that means the next drawer item will be stored (since the last item isn't a collapsed group)
edit: here's the for loop equivalent if it helps, with the full logic for when a calendar is not dropped (the logic in my other example is for whether it should be dropped, which can be condensed a bit):
// assuming 'calendars' is your list of items with 'collapsed' set appropriately
val result = mutableListOf<CalendarDrawerListItem)
for (calendar in calendars) {
val lastStored = result.lastOrNull()
when {
lastStored == null ->
result.add(calendar)
lastStored is CalendarDrawerGroupItem && !lastStored.collapsed ->
result.add(calendar)
lastStored is CalendarDrawerCalendarItem ->
result.add(calendar)
}
}
return result
If you're asking how to actually mutate your list so a collapsed property is set to true, that would be easy if the property was a var in your data class. Since it's a val you'll have to do something like this:
val calendarInputWithCollapsedSet = calendars.map { calendar ->
if ((calendar as? CalendarDrawerGroupItem)?.groupDescriptor == group.groupDescriptor)
calendar.copy(collapsed = true) else calendar
}
So if you find a matching group (you'll have to work out how to match them, I'm guessing) you transform it into a copy with its collapsed property set
And then you can run the fold or whatever on that new list.
ViewModel
fun changeQty(textField: TextFieldValue) {
val temp1 = textField.text
Timber.d("textField: $temp1")
val temp2 = temp1.replace("[^\\d]".toRegex(), "")
Timber.d("temp2: $temp2")
_qty.value = textField.copy(temp2)
}
TextField
OutlinedTextField(
modifier = Modifier
.focusRequester(focusRequester = focusRequester)
.onFocusChanged {
if (it.isFocused) {
keyboardController?.show()
}
},
value = qty.copy(
text = qty.text.trim()
),
onValueChange = changeQty,
label = { Text(text = qtyHint) },
singleLine = true,
keyboardOptions = KeyboardOptions(
keyboardType = KeyboardType.Number,
imeAction = ImeAction.Done
),
keyboardActions = KeyboardActions(
onDone = {
save()
onDismiss()
}
)
)
Set KeyboardType.Number, it display 1,2,3,4,5,6,7,8,9 and , . - space.
I just want to get integer like -10 or 10 or 0.
But I type the , or . or -(not the front sign), it show as it is.
ex)
typing = -10---------
hope = -10
display = -10---------
I put regular expression in
val temp2 = temp1.replace("[^\\d]".toRegex(), "")
But, it doesn't seem to work.
How I can get only integer(also negative integer)?
Use this regex (?<=(\d|-))(\D+) to replace all non digit characters, except first -.
fun getIntegersFromString(input: String): String {
val pattern = Regex("(?<=(\\d|-))(\\D+)")
val formatted = pattern.replace(input, "")
return formatted
}
Check it here
I'm trying to do a simple query. I want to have a list with a string and a Guid and a sub-list with a decimal and a string. I have my query this way but it keeps getting error when translated to Entity Framework what am I doing wrong?
Thanks in advance
var a = ( from c in DbContext.CC
join icc in DbContext.ICC c.Id equals icc.CCId
join i in DbContext.I on icc.IId equals i.Id
join p in DbContext.P on i.PId equals p.Id
select new
{
GuidId = p.Id,
StringN = p.StringN,
CCString = c.CCString ,
DecimalValue = icc.DecimalValue
}).GroupBy(x => new { x.GuidId , x.StringN }).
Select(x => new Model
{
GuidId = x.Key.GuidId ,
StringN = x.Key.StringN ,
Values= x.Select(y => new OtherModel
{
DecimalValue = y.DecimalValue ,
CCString = y.CCString
})
}
).OrderBy(x => x.StringN );
Error:
The LINQ expression '(GroupByShaperExpression:
KeySelector: new {
GuidId = (p.Id),
StringN = (p.Name)
},
ElementSelector:new {
GuidId = (ProjectionBindingExpression: GuidId ),
StringN = (ProjectionBindingExpression: StringN ),
CCString = (ProjectionBindingExpression: CCString ),
DecimalValue = (ProjectionBindingExpression: DecimalValue )
}
)
.Select(y => new OtherModel{
DecimalValue = y.DecimalValue ,
CCString = y.CCString
}
)' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to either AsEnumerable(), AsAsyncEnumerable(), ToList(), or ToListAsync(). See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.
It is SQL limitation. You cannot select grouped items, only Key and aggregation result is allowed.
Add AsEnumerable to your LINQ query to do grouping on the client side:
var a = (
from c in DbContext.CC
join icc in DbContext.ICC c.Id equals icc.CCId
join i in DbContext.I on icc.IId equals i.Id
join p in DbContext.P on i.PId equals p.Id
select new
{
GuidId = p.Id,
StringN = p.StringN,
CCString = c.CCString,
DecimalValue = icc.DecimalValue
})
.AsEnumerable()
.GroupBy(x => new { x.GuidId , x.StringN })
.Select(x => new Model
{
GuidId = x.Key.GuidId,
StringN = x.Key.StringN,
Values = x.Select(y => new OtherModel
{
DecimalValue = y.DecimalValue,
CCString = y.CCString
})
})
.OrderBy(x => x.StringN);
I want to merge same "startime" to one (step, distance and calorie) in the list, how can I to do this.
var listNewStepData = arrayListOf<NewStepData>()
data class
data class NewStepData (
val startTime: String?,
val endTime: String?,
val step: Int? = 0,
val distance: Int? = 0,
val calorie: Int? = 0
)
this is sample
NewStepData(startTime=2020-04-14T00:00:00.000Z, endTime=2020-04-14T00:00:00.000Z, step=4433, distance=0, calorie=0)
NewStepData(startTime=2020-04-14T00:00:00.000Z, endTime=2020-04-15T00:00:00.000Z, step=0, distance=0, calorie=1697)
NewStepData(startTime=2020-04-14T00:00:00.000Z, endTime=2020-04-14T00:00:00.000Z, step=0, distance=2436, calorie=0)
NewStepData(startTime=2020-04-15T00:00:00.000Z, endTime=2020-04-15T00:00:00.000Z, step=5423, distance=0, calorie=0)
NewStepData(startTime=2020-04-15T00:00:00.000Z, endTime=2020-04-16T00:00:00.000Z, step=0, distance=0, calorie=1715)
NewStepData(startTime=2020-04-15T00:00:00.000Z, endTime=2020-04-15T00:00:00.000Z, step=0, distance=3196, calorie=0)
I want to get this
NewStepData(startTime=2020-04-14T00:00:00.000Z, endTime=2020-04-15T00:00:00.000Z, step=4433, distance=2436, calorie=1697)
NewStepData(startTime=2020-04-15T00:00:00.000Z, endTime=2020-04-16T00:00:00.000Z, step=5423, distance=3196, calorie=1715)
thanks
You can use groupBy { } for your list. It will return a map of your grouping variable type to lists of your original type. And then, use flatMap to aggregate your data.
I assume that you take maximum end date which is maxBy and sum of distances, and steps which you need sumBy for, and calories which sumByDouble is the best choice.
Here's the sample code:
var grouped = listNewStepData.groupBy { it.startTime }.flatMap { entry -> NewStepData(startTime = entry.key,
endTime = entry.value.maxBy { item -> item.endTime },
step = entry.value.sumBy { item -> item.step },
distance = entry.value.sumBy { item -> item.distance },
calorie = entry.value.sumByDouble { item -> item.calorie })
}
My array has this dictionary I want to find and replace where dictionary h
attendance = "" and attendance = "A" and replace with attendance = "P"
I am using this:
checkedArray = [[String : AnyObject]]()
let index = find(checkedArray) { $0["attendance"] == "P" }
if let index = index {
checkedArray[index] = newDictionary
}
// Do any additional setup after loading the view.
}
func find<C: CollectionType>(collection: C, predicate: (C.Generator.Element) -> Bool) -> C.Index? {
for index in collection.startIndex ..< collection.endIndex {
if predicate(collection[index]) {
return index
}
}
return nil
}
[
{"studentID":"12","name":"panky","roll":"","attendance":"P"},
{"studentID":"14","name":"a","roll":"","attendance":""},
{"studentID":"4","name":"akshay","roll":"1","attendance":"E"},
{"studentID":"6","name":"anki","roll":"11","attendance":"P"},
{"studentID":"1","name":"mohit","roll":"2","attendance":"M"},
{"studentID":"5","name":"yogi","roll":"22","attendance":"L"},
{"studentID":"3","name":"Neha","roll":"3","attendance":"A"}
]
let dic: [[String : Any]] = [
["studentID":"12","name":"panky","roll":"","attendance":"P"],
["studentID":"14","name":"a","roll":"","attendance":""],
["studentID":"4","name":"akshay","roll":"1","attendance":"E"],
["studentID":"6","name":"anki","roll":"11","attendance":"P"],
["studentID":"1","name":"mohit","roll":"2","attendance":"M"],
["studentID":"5","name":"yogi","roll":"22","attendance":"L"],
["studentID":"3","name":"Neha","roll":"3","attendance":"A"]
]
let result : [Any] = dic.map { dictionary in
var dict = dictionary
if let attendance = dict["attendance"] as? String, attendance == "" || attendance == "A" {
dict["attendance"] = "P"
}
return dict
}