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I need to make a graph to compare 2 graph lines on time, but values from one are too high to the other, is there any way to make 1 graph line to a 1 y-axis and the other line to a second y-axis?

Hebert,

How about putting two graphs on the same page each with a different Y axis scale and the same X axis scale?

James

James Bott wrote:Hebert,

How about putting two graphs on the same page each with a different Y axis scale and the same X axis scale?

James

Hebert,

If they are two different graphs, then they can have different ranges on the Y-axis and the increments will be different. So, for instance, the bottom graph could have a range from 300,000 to 500,000 and the top one could have a range from 400,000 to 5 million even if both graphs are physically the same height.

Another option is to just divide the gas values by 10 and plot them on the same graph. Since you are looking for interactions, the exact values seem to be of less importance.

It would also be interesting to plot the difference between the two values (measured at the same time). This would probably tell you more about the interaction than plotting them both separately.

I'm not sure what you wanted me to see in the other message thread about charts?

James

All right James, I'll give it a try, I'll show the result on this post.

Heber,

As I suggested, try dividing all the gas values by 10 and plotting them. If that works then all you have to do is figure out how to place the Y-axis values on the right side.

But also, think of the bigger picture. Maybe there is a better way to find answers. That's why I also suggested plotting the difference between the two values. Sometimes you have to give them what they need instead of, or in addition to, what they want.

James

James Bott wrote:Heber,

As I suggested, try dividing all the gas values by 10 and plotting them. If that works then all you have to do is figure out how to place the Y-axis values on the right side.

But also, think of the bigger picture. Maybe there is a better way to find answers. That's why I also suggested plotting the difference between the two values. Sometimes you have to give them what they need instead of, or in addition to, what they want.

James

James,

Could you please post the sample code here ? Looks interesting for later use.

Thanks.

James Bott wrote:Here's the source. Remember, don't copy it using MS Edge.

James

Code (fw): Select all Collapse

/*
Purpose: Test charting to items with vastly different scales on the same chart
Author : James Bott
For    : Hebert Vargas
Date   : 08/07/2017 07:28:29 AM
*/

#include "Fivewin.ch"
#include "TGraph.ch" 


FUNCTION MAIN() 
                                                                                        
    LOCAL oDlg, oGraph, aData1, aData2, i
    
    // Assign the data
    aData1:= { 14280, 20420, 12870, 25347, 7640 }
    aData2:= { 7520000, 11220760, 9745154, 10125000, 12210000 }

    // Modify aData2 array values to fit chart scale
    for i = 1 to len(aData2)
       aData2[i] := aData2[i] / 1000 * 2.1
    next

    DEFINE DIALOG oDlg; 
           SIZE 600, 500 

    @ 1, 1 GRAPH oGraph; 
           SIZE 285, 220; 
           TYPE 3; 
           YVALUES 3D XGRID YGRID XVALUES LEGENDS
           
    oGraph:nPoint:=1
    
    //msgInfo( oGraph:nPenWidth)
    oGraph:nPenWidth:=5 // has no effect on pen width. (bug?)     
           
           
    oGraph:nType := 3                        // 3=line chart
    oGraph:cSubTit:= "Oil & Gas Flow Rates"

    oGraph:aSeries = { { "Crude Oil MBD", CLR_HBLUE ,, },{ "Gas MMPCD", CLR_HRED ,, }}
    oGraph:aData = { aData1 ,  aData2  }

    // Y-axis data. Note they are incorrectly labled "X"
    oGraph:nMaxVal:= 30000
    oGraph:nXRanges:= 6   // number of y-axis label increments
    oGraph:cTitX := "Oil Flow Rate MBD" 
    
    // X-Axis data. Note that they are incorrectly labled with a "Y" 
    oGraph:aYVals = { "1", "2", "3", "4", "5" }  // Should these be dates?
    oGraph:cTitY:="Days?"
 

    ACTIVATE DIALOG oDlg; 
             CENTER 
             
    //msgInfo( oGraph:nPenWidth )

RETURN NIL
 
// EOF

I appreciate your ingenuity in finding a nice workaround.
Now TGraph does not support 2 Y-Axis and we all agree that this is a required feature.
We shall provide this very soon.

Nages,

TGraph is a great class, however, it does have it's shortcomings.

Most of the variable names are very cryptic and many are misleading which causes constant confusion. For instance, the X and Y axis variables are swapped. The X variables are really for the Y-axis and visa versa. Very confusing.

For instance, these are for the Y-axis and either do not contain a "Y" or contain an "X" instead:

nMaxVal - This is actually the maximum value of the Y-axis but is not labeled with a "Y" and there is no setting for the maximum X-axis. The variable name should be nYMaxValue.

nXRanges - number of Y-axis label increments. This would be better labeled nYIncrements

cTitX - This is for the Y-axis and would be better named cYTitle. One wonders, why was it abbreviated to save two characters in the name.

These are for the X-axis and are mistakenly labeled with a "Y" instead:

aYVals - list of X-axis values for increment labels. Should be aXIncrementValues

cTitY – This is the title for the X-axis. It should be cXTitle.

These are just some examples–there are many more.

One other issue that the X-axis can only be used as a time-series type increment (i.e. you can’t put points between the X-axis increments). This makes the class very limited.

Of course, changing variable names will break existing code, so I suggest creating a new class instead of making any changes to the existing one.

I’m sure others will have some input on this as well.

Oh, I should also note that the wiki for the TGraph class has the wrong descriptions for the variables for the X and Y axises.

James