Cartograms in ArcGIS

Now there’s a script that you can download so that ArcGIS can make cartograms…we all love them on sites like Worldmapper, and now you can make your own!

The script is found at http://arcscripts.esri.com/details.asp?dbid=15638.

Yikes! Missing a toolbar and/or the Table of Contents?

If the Table of Contents has disappeared, go to the Window menu and click on Table of Contents. It should reappear like magic where you last saw it.

To get back a toolbar, just go to View, then click Toolbars, and select the one you need. The Standard and Tools toolbars have most of the common commands.

If you can’t see ArcToolbox, it can be found in the Window menu just below the Table of Contents. Simply click on ArcToolbox and it will appear.

How do I calculate numbers in ArcMap and display the results?

The easiest way is to use the Statistics tool. Just open an attribute table and right-click the column heading, then select the “statistics” button and a new window will open with summary statistics for the data.

Another way is to use the Field Calculator. This will allow you to compute more complex calculations. You may want to add a new field when using this tool, as otherwise it will overwrite the information already in your attribute table.

There are many other tools to do many other kinds of calculations in ArcMap. We can help you determine which tool would work best for your project.

Can I show two (or more) themes with one layer?

Some of the time you may want to display two sets of information with one GIS data layer. For example, you might want to show both average income and median age of the population.

The easiest way to show two themes of a single geographic layer is simply to use two copies of that layer in your map document, with each layer showing one theme.

You can repeat this process for additional themes, but always continue to ask: does adding this additional information make my map harder to understand? If you try to show too many things in one map, it may be too cluttered to show your point effectively.

(You can also save symbology by creating a .lyr file…the ArcGIS Help documentation has details on how to do this.)

My layer/labels don’t look like I want them to!

This is a fairly common problem caused by ArcMap’s default settings. Your layer comes with preferences toward displaying everything in one color and using a particular field for labeling.

To fix this problem, double click the layer name to go to the layer’s properties and change the settings. The “Symbology” tab will let you change the color and theme of the layer and the “Label” tab will let you change the color, size, and field displayed of your labels. You might also consider using annotations instead of labels to give yourself more flexibility.

My raster appears as a black box! Is the file bad?

Your data is not lost; the settings are just wrong. This is a fairly common problem caused by ArcMap’s default settings. Your raster is simply being displayed entirely in one color.

To fix this problem, double click the layer name and click on the “Symbology” tab to go to the raster’s symbology and change the settings to a graduated color scheme. Play around with the settings a bit, and it should show up as you want it!

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