Android Question How to replace null values with zero's in double array?

RB Smissaert · Apr 24, 2020

This sounds like a simple thing, but not managed it so far.
What would be the best way to do this?

RBS

stevel05 · Apr 24, 2020

How are you creating the double array?

RB Smissaert · Apr 24, 2020

stevel05 said:
How are you creating the double array?

Mainly from SQLite.
I know I can avoid the null values at source, but I still need to check and clear from the array.

RBS

stevel05 · Apr 24, 2020

If you can't change the source to exclude nulls, then I think you will have to cast the array initially to an array of object to do the conversion, then create the Double array, replacing the nulls as you go.

B4X:

'ObjArr is an array of Object read from the database
Dim DblArr(ObjArr.Length) As Double
For i = 0 To ObjArr.Length - 1
    Dim O As Object = ObjArr(i)
    If O = Null Then
        DblArr(i) = 0
    Else
        DblArr(i) = O
    End If
Next

OliverA · Apr 24, 2020

stevel05 said:
How are you creating the double array?

RB Smissaert said:
Mainly from SQLite.

I feel dumb. How is this achieved?

RB Smissaert · Apr 24, 2020

OliverA said:
I feel dumb. How is this achieved?

Copy ResultSet values to double array.

RBS

klaus · Apr 24, 2020

Maybe this:

B4X:

str = Curs.GetString2(col)
If str <> Null Then
   dd = Curs.GetDouble2(col)
Else
   dd = 0
End If

RB Smissaert · Apr 24, 2020

klaus said:
Maybe this:

B4X:

str = Curs.GetString2(col) If str <> Null Then dd = Curs.GetDouble2(col) Else dd = 0 End If

Thanks, that seems to work indeed.

RBS

RB Smissaert · Apr 24, 2020

klaus said:
Maybe this:

B4X:

str = Curs.GetString2(col) If str <> Null Then dd = Curs.GetDouble2(col) Else dd = 0 End If

This all has to do with the table sorting. Null values seriously mess up the Double QuickSort.

RBS

Mahares · Apr 24, 2020

klaus said:
If str <> Null Then

I usually do not argue with klaus. Shouldn't this be:

B4X:

If str <> Null and isnumber(str) Then

klaus · Apr 24, 2020

Sure, it's more universal.
But, it seems that he expects a Double therefore the 'limited' code works.
Because, I hope so, the type check was done before.

Star-Dust · Apr 24, 2020

klaus said:
Sure, it's more universal.
But, it seems that he expects a Double therefore the 'limited' code works.
Because, I hope so, the type check was done before.

Mahares said:
I usually do not argue with klaus. Shouldn't this be:

B4X:

If str <> Null and isnumber(str) Then

I also normally don't contradict @klaus, but I think this time I disagree with his solution.
If you use this statement str = Curs.GetString2(col) and the value is null str does not become null but sometimes str = "null" as a string, I would do so

B4X:

str = Curs.GetString2(col)
If str <> Null And str<>"null" Then
     If isnumber(str)  Then
     End IF
End IF

LucaMs · Apr 24, 2020

Star-Dust said:
I also normally contradict @klaus, but I think this time I disagree with his solution.
If you use this statement str = Curs.GetString2(col) and the value is null str does not become null but sometimes str = "null" as a string, I would do so

B4X:

str = Curs.GetString2(col) If str <> Null And str<>"null" Then If isnumber(str) Then End IF End IF

The check can be done in a single line:

B4X:

str = Curs.GetString2(col)
If str <> Null And str <> "null" And IsNumber(str) Then
'
End IF

Star-Dust · Apr 24, 2020

LucaMs said:
The check can be done in a single line:

B4X:

str = Curs.GetString2(col) If str <> Null And str <> "null" And IsNumber(str) Then ' End IF

I'm not sure that isNumber with a null value doesn't generate a runtime error

OliverA · Apr 24, 2020

B4X short circuits logical evaluations. The first false expression in an and expression stops checking and therefore does not evaluate any other expressions in the statement.

Mahares · Apr 24, 2020

Since the OP retrieves data from a SQLite table, shouldn't he try to avoid the presence of a null in any of his output by simply invoking the Ifnull function like this or am I slow to catch up to this debate:

B4X:

ifnull(mycol, 0) as col

Star-Dust · Apr 24, 2020

Mahares said:
@Star-Dust: I think you mean to say: 'I also normally DO NOT contradict @klaus, '

Right, a typing mistake ?

Android Question How to replace null values with zero's in double array?

RB Smissaert

Well-Known Member

stevel05

Expert

RB Smissaert

Well-Known Member

stevel05

Expert

OliverA

Expert

RB Smissaert

Well-Known Member

klaus

Expert

RB Smissaert

Well-Known Member

RB Smissaert

Well-Known Member

Mahares

Expert

klaus

Expert

Star-Dust

Expert

LucaMs

Expert

Star-Dust

Expert

OliverA

Expert

Mahares

Expert

Star-Dust

Expert

Similar Threads

Android Question How to replace null values with zero's in double array?

Well-Known Member

Expert

Well-Known Member

Expert

Expert

Well-Known Member

Expert

Well-Known Member

Well-Known Member

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Similar Threads

Privacy & Transparency

Privacy & Transparency