3 replies to this topic

[Kristin]

Hello,

 

I am working on a student project in ArcGIS using exploratory spatial statistics.  I have several datasets that show trend values that I would like to compare.  I would like to use a continuous color scheme with divergent colors and would like to 'center' the color scheme at 0, rather than the data mean.  Is there a way to do this?  The range of the data also varies between datasets so ideally I would like to also set the range to the max dataset so that all of the layers may be shown consistantly.

 

Right now I just have the data in categories, however they are a little finnicky to change...

 

Thanks in advance for your help!

[frax]

Short answer - yes, you can (I think) - but it is a bit finicky...

[AndrewM]

Hi Kristin, this actually isn't too hard to do in ArcMap - I'm guessing from what you're doing your data is in raster format. Firstly before you start just note down the maximum and minimum values of the datasets that you will be displaying.

 

To set the colour ramp right click on your first data layer, click 'properties', go to the 'symbology' tab and then choose 'stretched' from the options on the left, then choose the divergent colour scheme you want to use from the color ramp list (this is probably where you are already).

 

To change how it is displayed you then need to scroll down to the bottom of the page and find the 'statistics' section. Here there is a dropdown tab which by default is always set to 'from each raster dataset'. Click the dropdown and change this to 'from custom settings (below)'. This allows you to specify your own parameters for how the colour ramp is applied.

 

Then all you need to do is input your maximum and minimum values that you noted down already in the max and min boxes and change the mean to 0 - it will now use 0 as the centre of your colour ramp. Standard deviation is a bit trickier but to be honest as long as it's similar for all your datasets you can probably just leave that as it is.

 

To apply the same to your other datasets you just need to ensure they have their colour ramp set to stretched and then click on 'import' at the top right of the window. You can now import the colour ramp from your first layer to save having to manually enter all of the values again.

 

Hope that helps!

[Kristin]

Thanks! That does help - I hadn't used these settings before.  I was actually looking at vector data, but I don't think there is any way to apply a continuous color scheme let alone set mean and range, so I will likely just end up converting to raster for display.

 

Cheers,

Kristin