sequential numbers in batches

[Raynok1]

Hi,

I've got the following data layout,

Item		Assigned
1		Person1
2		Person1
3		Person1
4		Person1
5
6
7
8
9
10		Person3
11
12
13
14
15
16
17
18		Person2
19		Person2
20		Person2
….1000 records

The goal or idea is allow a person input a number which represents a batch of available sequential numbers.

For instance "person 4" wants a batch of 5 items. 

The powerapp should assign "person 4" to the following available slots.

The powerapp must always be able to find available sequential numbers in batches based on the amount input.

Item		Assigned
1		Person1
2		Person1
3		Person1
4		Person1
5		Person4
6		Person4
7		Person4
8		Person4
9		Person4
10		Person3
11
12
13
14
15
16
17
18		Person2
19		Person2
20		Person2
….1000

Need help to figure out how to achieve this. Anyone know?

[Mr-Dang-MSFT · Accepted solution]

Oh this is a fun problem!

We need each record to be aware of its neighboring records. Thinking in this direction, we'll try to find what records are nearby that would be consecutive below it (min) and above it (max). This gets us a range of Item #s which we can filter later.

For best performance, let's Collect the entire set of Items locally. We can shape the Items very easily in collections with no limits by delegation or delay due to calls to a connected data source. 

Execute this action in a button or OnVisible:

ClearCollect(colItems,Items)

This means, "Collect all of the Items from the table to a collection called colItems." 

Our collection can compare against itself--and at multiple levels. We will need to make each row of colItems compare against the same rows of the table. If you were to try this against the connected datasource, it would not be very performant at all--don't do that.

The diagram below shows an example of 3 levels of colItems comparing against itself:

• Suppose you wanted to find the minimum consecutive record near Item #7. We know that the answer is going to be a range of 5-9 with the minimum as 5. Let's calculate how to get 5 as the minimum.
• First we compare 7 to every other record:
  • Which other records are blank?
  • Which other records are less than 7?
  • Of those, we get [5,6]. If you were to find the absolute value between each of those and 7, which ones are the same distance away as the number of unassigned records that should exist in between them?
  • Ex: 7-5=2. Check if there are 2 records that are unassigned between 5 and 7. If so, 5 is consecutive. If there is one assigned in between 5 and 7, 5 is not consecutive.
  • Ex: 7-6=1. Check if there is 1 record that is unassigned between 6 and 7. If so, 6 is consecutive. If there is one assigned in between 6 and 7, 6 is not consecutive.

Filter(
    AddColumns(
        colItems,
    "Min",
        // Find the lowest consecutive Item.
        If(
            IsBlank(Assigned),
            Min(
                // Return the given Item as the lower boundary if no others are found nearby.
                Item,
                Min(
                    // For each Item, look at all blank items before it. 
                    Filter(RenameColumns(Sort(Items,Item),"Item","ItemID_1"),
                        IsBlank(Assigned),
                        ItemID_1<Item,

                        // Determine if a record is consecutive if its distance to the main Item is equal to the amount of records in between.
                        // A record is not consecutive if another Item had been assigned in between, throwing off the count. 
                        Abs(ItemID_1-Item)=CountRows(Filter(RenameColumns(Sort(Items,Item),"Item","ItemID_2"),IsBlank(Assigned),ItemID_2<Item,ItemID_2>=ItemID_1))
                    ),
                    ItemID_1
                )
            )
        ),
    "Max",
        // Find the highest consecutive Item.
        If(
            IsBlank(Assigned),
            Max(
                Item,
                Max(
                    Filter(RenameColumns(Items,"Item","ItemID_1"),
                        IsBlank(Assigned),
                        ItemID_1>Item,
                        Abs(ItemID_1-Item)=CountRows(Filter(RenameColumns(Sort(Items,Item),"Item","ItemID_2"),IsBlank(Assigned),ItemID_2>Item,ItemID_2<=ItemID_1))
                    ),
                    ItemID_1
                )
            )
        )
    ),
    Max-Min+1>=Slider1.Value
)

1.  Starting inside and going out, colItems is the local collection of Items.
2. I add two columns to it, representing what range of consecutive items it belongs to: Min, Max.
3. I filter the range to only show records that match a given interval controlled by Slider1.

Let's break apart the calculation for Min. Note I did not put many comments into Max since it's a similar pattern, only opposite.

If(
    IsBlank(Assigned),
    Min(
        // Return the given Item as the lower boundary if no others are found nearby.
        Item,
        Min(
            // For each Item, look at all blank items before it. 
            Filter(RenameColumns(Sort(Items,Item),"Item","ItemID_1"),
                IsBlank(Assigned),
                ItemID_1<Item,

                // Determine if a record is consecutive if its distance to the main Item is equal to the amount of records in between.
                // A record is not consecutive if another Item had been assigned in between, throwing off the count. 
                Abs(ItemID_1-Item)=CountRows(Filter(RenameColumns(Sort(Items,Item),"Item","ItemID_2"),IsBlank(Assigned),ItemID_2<Item,ItemID_2>=ItemID_1))
            ),
            ItemID_1
        )
    )
)

• This means, "If the given Item is unassigned (Assigned is blank), calculate a minimum consecutive Item.
  • Compare the given Item against the same collection to find records that are less than its Item number and unassigned.
  • Compare the difference between the respective item against the count of records that should exist in between. If they match, they are consecutive.
  • Of the records that would match, pick the smallest one to represent the start of the consecutive range.
  • In the event that a record has no unassigned records preceeding it, make it the start of the range (the outer Min function).

You can see the attached app for an example of this in action.

Let me know if this was helpful.

Mr. Dang

[Raynok1]

Hi Mr Dang,
Big Fan of your work! This made my day.

Downloaded the sample app and its a massive help. Going over code as much as I can. Thank you, for the explanations.

I've applied the code to the "onchange" property of the slicer in order to take the results into another collection. My next step is linking a gallery to the new collection for multi selection editing which will then be written back to the source.

This was very helpful and the desired result looks achievable, will let you know. Thank you!

Big Fan! From South Africa.

[Mr-Dang-MSFT]

@Raynok1,

I'm happy this was helpful. It is incomplete though as you'll probably need to use GroupBy to stick together each set of Items. Good luck with the rest of it and feel free to share your add-ons so others can learn from you. 🤓

[Raynok1]

@Mr-Dang-MSFT 

Like bait to a fish "It is incomplete though as you'll probably need to use GroupBy to stick together each set of Items".

If assuming correctly, we'll create a index number for each batch/group on a new column? Yeah that'll be great.

What did you have in mind?

[Mr-Dang-MSFT]

In its current form, the app reduces the Items to only the unassigned items. But each Item is still an individual record. If you click 7, you will only have 7 selected. But what you actually want is to select 5-9 with one click.

The GroupBy function takes one column of that table and effectively looks for unique values. In the image above, 5 and 11 are the two unique values for Min. Then for each unique value, it creates a child table of the rows that match. 

If I were to use the formula below:

GroupBy(the_entire_formula_shared_earlier, "Min", "ItemSet")

This creates a table with two rows under the Min column: 5, 11.

Beside the row for 5 is a table whose name is ItemSet and contains items 5-9 since they match the value of 5 in the Min column. 

Beside the row for 11 is a table of items 11-17.

The child table would contain columns for Item, Assigned, and Max.

Now that the items are grouped, you can take action on a selected group.