Left and right axis with common zero

Share icon

Hi,

I want to modify a graph with a left and a right y axis in a way that the zero points of both are in the same height, but the axes should still have different scales and not necessarily be Symmatric around zero.

The Data I'm using can look something like this:

•Make/N=100 DataL=gnoise(5)
•Make/N=100 DataR=gnoise(0.2)-0.2
•Display/L DataL
•AppendToGraph/R DataR

Does Somebody know how to do this?

Thank you for your time,

sincerely,

Sven

This is close, I think:

Function DoStuff()
    Make/O/N=100 DataL=gnoise(5)
    Make/O/N=100 DataR=gnoise(0.2)-0.2
    Display/L /N=myGraph DataL
    AppendToGraph/R DataR
    SetWindow myGraph, hook(alignZero)=AlignZeroHook
End
 
Function AlignZeroHook(s)
    STRUCT WMWinHookStruct &s
 
    Variable hookResult = 0
 
    switch(s.eventCode)
        case 8:             // Modified
            
            GetAxis/W=myGraph left
            variable vLeftRange = V_max - V_min
            Variable vLeftMin = V_min
            GetAxis/W=myGraph right
            variable vRightRange = V_max - V_min
            Variable vRightMin = V_min
            
            Variable vNewRightMin = vLeftMin * vRightRange / vLeftRange
            
            SetAxis/W=myGraph right vNewRightMin, (vNewRightMin + vRightRange)
            hookResult = 1
            
            break
    endswitch
 
    return hookResult       // 0 if nothing done, else 1
End

Hope this gives some ideas,

Kurt

 

February 28, 2019 at 08:19 am - Permalink

Hello Kurt,

I like the idea. The Problem here is that in your code the range is kept constant, thus a part of the Data is not visible anymore. So I Changed it a little bit:

Function AlignZeroHook(s)
    STRUCT WMWinHookStruct &s
 
    Variable hookResult = 0
    
        switch(s.eventCode)
            case 8:             // Modified
                
                //Go to automatic Scaling of right axis to get hole DataRange
                SetAxis/W=$(s.WinName)/A right
                DoUpdate;
 
                GetAxis/Q /W=$(s.WinName) left
                Variable LMax = V_max
                Variable LMin = V_min
                variable LRng = V_max - V_min
                GetAxis/Q /W=$(s.WinName) right
                variable RMax = V_max
                Variable RMin = V_min
                Variable RRng = V_max - V_min
                
                //look whether the top or the lower range have to be extended
                If(RMax/RRng>LMax/LRng)
                    Variable NewRMin=RMax-(RMax/LMax*LRng)
                    SetAxis/W=$(s.WinName) right NewRMin, *
                else
                    Variable NewRMax=(RMin/LMin*LRng)+RMin
                    SetAxis/W=$(s.WinName) right *, NewRMax
                endif
                hookResult = 1
           
                break
        endswitch
 
    return hookResult       // 0 if nothing done, else 1
End

It now just get stuck if the left axis has no zero at all.

Thank you very much.

Sincerly,

Sven

March 1, 2019 at 02:38 am - Permalink