Relative scaling of bubble size: how to change

[#1]

I have made a grid chart with bubble reflecting the volume sold to certain customer/product combinations. It appears that the relative scaling of the bubbles is not correct. When the volume of a certain product/customer combination is twice as big, the bubble appears to be at least 4x bigger.

Two questions:

• Does anybody know how the relative bubbel size is determined? Is my observation correct?
• Can I change the approach used for the relative scaling of the bubbbles?

Thanks,  Marc.

[swuehl]

I assumed so far that the bubble size will scale from zero to the max bubble size set linearly, where the size will be set by the bubble size expression and the 'bubble size' will be proportional to the area of the bubble.

Well, anyway, you can use any expression as bubble size expression, so if you think the bubble appears 4x larger if your expression gives only a 2x value, just use something like

=sqrt( sum(Volume) )

i.e. calculate the square root of your values.

Hope this helps,

Stefan

[#3]

Hi, thanks for the reply. This is what I did, use the square root to get the proper scaling. But this has a major drawback: if you mouse over the bubbles to get the value of the bubble (which I use a lot), you get a aeamningless number. So I would prefer a different solution. Any ideas?

[swuehl · Accepted solution]

Try using a dual as bubble size expression outcome, something like

dual( sum(Volume), sqrt( sum(Volume) ) )

[#5]

Hi Stefan,

This seems to be the way to go. One detail: if I do this, the experession is sum(Volume) is not evaluated. How can I force evaluation of the expression and then display the result as a number?

[swuehl]

Not sure what you are talking about. I do get the expression evaluated.

Could you post a small sample file?

[#7]

Hi MarcD,

An alternative to make sure you have the right info when you mouse over the bubble is to create a 4th expression with the desired info. Something like:

=Customername  & ': number of products sold ' & ceil ( count ( distinct [Product numbers] ) ) // Pop_up text

Next, apply the option 'Text as Pop-up' under the Display Options.

This way you are able to modify and personalize the pop-up.