9 Replies Latest reply on Mar 13, 2015 11:31 AM by Alexander Mou

# Maps- Setting a maximum value instead of an End value

Hello All,

I've been searching to see if anyone has even raised this question but cannot find it anywhere. Forgive me if this has been raised before.

I have a map of the United States where I'm plotting the density of a specific population by CBSA. One CBSA has a rather large population, and if I show density by color, it swamps the scale. To solve this, I have set the maximum value at 1000. Colors show a broader range of densities now.

However, if I filter things on a characteristic that eliminates 80% of the population, The map colors no longer help, because I've pinned that maximum range to 1000.

Is there a way where I can get that max value to act more as a ceiling, while still allowing the colors to scale dynamically? In other words, I want the colors to behave dynamically according to population, but never attempt to scale above 1000.

Thoughts?

• ###### 1. Re: Maps- Setting a maximum value instead of an End value

Interesting question.  I don't know of a way to do that, but this is what I would do:

Create a calc for the value you are using for density.  Basically it would look something like this:

IF [value field] > 1000 then 1000 else [value field] end

Now do density on that calc field instead of [value field]. You can still put the actual [value field] on text and in your tooltips, so the user would still see the actual values, but your color (or sizing) won't overwhelm the rest of the values when there is a large value.

• ###### 2. Re: Maps- Setting a maximum value instead of an End value

You could even have a parameter where the users can set the threshold.

IF [value field] > [threshold param] then  [threshold param] else [value field] end

• ###### 3. Re: Maps- Setting a maximum value instead of an End value

Without seeing your workbook, this sounds like a case where creating a log of the measure you are using might help.

LN([measure]) to colorize vs measure.  I saw this solution somewhere some time ago but cannot find it today.

If I find it I will post here.

Here's what it would look like using normal color legend:

And here is same map using calc:  LN([Amount]):

Hope this helps

• ###### 4. Re: Maps- Setting a maximum value instead of an End value

I thought like what Joe Oppelt did.

But LN() is much more interesting for visual transformation. Thanks, David Walp

### Stellar magnitude

Hipparchos ranked stars in six magnitude classes according to their brightness: he assigned the value of one (today written 1,0 mag) to the twenty brightest stars, to fainter ones a value of two, and so forth to the stars with a class of six (6 mag), which can be barely seen with the naked eye. That system is effectively still in use today, though extended and made more precise through the introduction of a logarithmic scale by N. R. Pogson in 1856.

• ###### 5. Re: Maps- Setting a maximum value instead of an End value

Check out 3 Easy Tableau Tips for Confident, Clean-Shaven Maps | VizPainter for a description of the LN() approach in maps and a few other possibilities.

-Joshua

• ###### 7. Re: Maps- Setting a maximum value instead of an End value

Also proposed an idea on inclusion of a logarithmic option in color editor

http://community.tableau.com/ideas/4417

• ###### 8. Re: Maps- Setting a maximum value instead of an End value

I want to thank everyone for their great ideas! I REALLY like the LN() approach and I'm going to utilize that in the future. For now though, I'm going to tag Joe Oppelt's initial answer as the correct one. Honestly though, everyone added some great thoughts on this topic. Thank you so much!

• ###### 9. Re: Maps- Setting a maximum value instead of an End value

James,

Since you really like it, vote this up then.

http://community.tableau.com/ideas/4417