Android Question B4XOrderedMap sort on values, does it work?

RB Smissaert · May 23, 2020

Working on typing suggestions and need to order on word frequencies and for this I am using a B4XOrderedMap.
The frequencies are the values and the words the key.
Trying to sort on values but can't get it to work:

B4X:

 If mapSuggestionsCounts.Size > 1 Then
  mapSuggestionsCounts.Values.Sort(False)
 End If
 
 For  i = 0 To mapSuggestionsCounts.Size - 1
  Log("GetSuggestions, key: " & mapSuggestionsCounts.Keys.Get(i)  & " - value: " & mapSuggestionsCounts.Values.Get(i))
 Next
 
 For Each iValue In mapSuggestionsCounts.Values
  Log("GetSuggestions, value: " & iValue)
 Next

Gives in the log:

GetSuggestions, key: pat_deprivation - value: 0
GetSuggestions, key: pat_stats - value: 0
GetSuggestions, key: path_points - value: 0
GetSuggestions, key: patient_count - value: 0
GetSuggestions, key: patient_list - value: 0
GetSuggestions, key: patient_type - value: 0
GetSuggestions, key: patient_warnings - value: 0
GetSuggestions, key: patients - value: 3
GetSuggestions, key: patients_points - value: 0
GetSuggestions, key: pats - value: 0

GetSuggestions, value: 0
GetSuggestions, value: 0
GetSuggestions, value: 0
GetSuggestions, value: 0
GetSuggestions, value: 0
GetSuggestions, value: 0
GetSuggestions, value: 0
GetSuggestions, value: 3
GetSuggestions, value: 0
GetSuggestions, value: 0

Keys are string and values are int, so no idea what is going on here.

RBS

Erel · May 24, 2020

No. Sorting the Values list doesn't change the collection order. Only the order of the Values list that you currently hold.

RB Smissaert · May 24, 2020

Erel said:
No. Sorting the Values list doesn't change the collection order. Only the order of the Values list that you currently hold.

OK, misunderstood that then.
In that case the syntax is a bit misleading as Keys.Sort does alter the order of the collection.
Also, I am not sure how B4XOrderedMap.Values.Sort works(see testing code), but I made a function
that does sort a B4XOrderedMap(with String keys) by Int values:

B4X:

Sub TestB4XOrderedMapValuesSort

Dim i As Int
Dim OM As B4XOrderedMap
Dim OMSortedOnIntValues As B4XOrderedMap
Dim lstValuesUnSorted As List
Dim lstValuesSorted As List
Dim lstValuesSorted2 As List

OM.Initialize

OM.Put("Key0", 10)
OM.Put("Key1", 2)
OM.Put("Key2", 6)

lstValuesUnSorted = OM.Values

For i = 0 To 2
Log("Before OM.Values.Sort: lstValuesUnSorted.Get(" & i & ")" & lstValuesUnSorted.Get(i))
Next

Log("OM.Values.Sort(True)")
OM.Values.Sort(True)

lstValuesSorted = OM.Values

For i = 0 To 2
Log("After OM.Values.Sort: lstValuesSorted.Get(" & i & ")" & lstValuesSorted.Get(i))
Next

Log("SortB4XOMByIntValues(OM, True)")
OMSortedOnIntValues = SortB4XOMByIntValues(OM,True)

lstValuesSorted2 = OMSortedOnIntValues.Values

For i = 0 To 2
Log("After SortB4XOMByIntValues: " & OMSortedOnIntValues.Keys.Get(i) & ":, lstValuesSorted2.Get(" & i & ")" & lstValuesSorted2.Get(i))
Next

End Sub
Sub SortB4XOMByIntValues(oB4XOM As B4XOrderedMap, bAscending As Boolean) As B4XOrderedMap

Dim i As Int
Dim arrKeys(oB4XOM.Size) As String
Dim arrValues(oB4XOM.Size) As Int
Dim arrIndex() As Int
Dim oB4XOMSorted As B4XOrderedMap

For Each strKey As String In oB4XOM.Keys
arrKeys(i) = strKey
arrValues(i) = oB4XOM.Get(strKey)
i = i + 1
Next

arrIndex = SortOMIntIDX(arrValues, bAscending, -1, -1)

If arrIndex(0) = -1 Then
'all values same, so return old B4XOrderedMap
Return oB4XOM
End If

oB4XOMSorted.Initialize

For i = 0 To arrIndex.Length - 1
oB4XOMSorted.Put(arrKeys(arrIndex(i)), arrValues(arrIndex(i)))
Next

Return oB4XOMSorted

End Sub
Sub Check1DIntAllSame(arrInt() As Int, iStart As Int, iEnd As Int) As Boolean

Dim i As Int
Dim iVal As Int

If arrInt.Length = 1 Then
Return True
End If

If iStart = -1 Then
iStart = 1
End If

If iEnd = -1 Then
iEnd = arrInt.Length - 1
End If

iVal = arrInt(0)

For i = iStart To iEnd
If arrInt(i) <> iVal Then
Return False
End If
Next

Return True

End Sub
Sub SortOMIntIDX(arrInt() As Int, bAscending As Boolean, iStart As Int, iEnd As Int) As Int()
 Dim i As Long
Dim c As Long
Dim n As Long
Dim B4XOM As B4XOrderedMap

If Check1DIntAllSame(arrInt, iStart, iEnd) Then
Dim arrIndex2(1) As Int
arrIndex2(0) = -1
Return arrIndex2
End If

B4XOM.Initialize

If iStart = -1 Then
iStart = 0
End If

If iEnd = -1 Then
iEnd = arrInt.Length - 1
End If

For i = iStart To iEnd
Dim lstIndexes As List
If B4XOM.ContainsKey(arrInt(i)) Then
lstIndexes = B4XOM.Get(arrInt(i))
Else
lstIndexes.Initialize
End If
lstIndexes.Add(i)
B4XOM.Put(arrInt(i), lstIndexes)
Next

B4XOM.Keys.Sort(bAscending)

Dim arrIndex((iEnd - iStart) + 1) As Int

For Each oValue As Object In B4XOM.Values
lstIndexes = oValue
For c = 0 To lstIndexes.Size - 1
arrIndex(n) = lstIndexes.Get(c)
n = n + 1
Next
Next

Return arrIndex

End Sub

RBS

Erel · May 24, 2020

B4XOrderedMap is explained here: https://www.b4x.com/android/forum/threads/b4x-b4xcollections-more-collections.101071/

RB Smissaert · May 24, 2020

Erel said:
B4XOrderedMap is explained here: https://www.b4x.com/android/forum/threads/b4x-b4xcollections-more-collections.101071/

I did look at that, but it didn't say much about Values.Sort and still not sure how that works.

RBS

Erel · May 24, 2020

B4XOrderedMap.Values returns a list with the values. Modifying this list will not affect the actual data in the collection. It is a copy.

RB Smissaert · May 24, 2020

Erel said:
B4XOrderedMap.Values returns a list with the values. Modifying this list will not affect the actual data in the collection. It is a copy.

Could you give a simple example of B4XOrderedMap.Values.Sort ?

RBS

Erel · May 24, 2020

It doesn't do anything that will help you.

Use a custom type with fields for all relevant information.
This will allow you to sort the values with Values.SortType.

RB Smissaert · May 24, 2020

Erel said:
It doesn't do anything that will help you.

Use a custom type with fields for all relevant information.
This will allow you to sort the values with Values.SortType.

I know how to sort, no problem with that.
Just wonder now how B4XOrderedMap.Values.Sort could help anybody.

RBS

Erel · May 24, 2020

B4XOrderedMap.Values returns a List. So the list includes all of the List methods. Whether it can be helpful or not is not related.

RB Smissaert · May 24, 2020

Erel said:
B4XOrderedMap.Values returns a List. So the list includes all of the List methods. Whether it can be helpful or not is not related.

OK, now I understand! Because it is a list it needs to show the Sort method, although in this case there is no use for it.
Is it not possible to hide methods from the user? If I remember well VBA and VB6 do this.

RBS

Erel · May 24, 2020

RB Smissaert said:
Is it not possible to hide methods from the user?

Of course not. It returns a regular List.

RB Smissaert · May 24, 2020

RB Smissaert said:
OK, now I understand! Because it is a list it needs to show the Sort method, although in this case there is no use for it.
Is it not possible to hide methods from the user? If I remember well VBA and VB6 do this.

RBS

Erel said:
Of course not. It returns a regular List.

I don't know how B4A works behind the scenes, but I meant to hide the Sort method from B4XOrderedMap.Values.
I understand that if you do lst = B4XOrderedMap.Values then lst needs to show the .Sort method.

RBS

Android Question B4XOrderedMap sort on values, does it work?

RB Smissaert

Well-Known Member

Erel

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RB Smissaert

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Erel

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RB Smissaert

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Erel

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RB Smissaert

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Erel

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RB Smissaert

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Erel

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RB Smissaert

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Erel

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