Working with legends
A legend tells a map reader the meaning of the symbols used to represent features on the map. Legends consist of examples of the symbols on the map with labels containing explanatory text. When you use a single symbol for the features in a layer, the layer is labeled with the layer's name in the legend. When you use multiple symbols to represent features in a single layer, the field you use to classify the features becomes a heading in the legend, and each category is labeled with its value.
Legends have patches that show examples of the map symbols. By default, the legend patches are points, straight lines, or rectangles that match the map symbols. You can customize the legend patches, for example, so areas are represented with patches of another shape or rivers are drawn with a sinuous rather than a straight line.
A quick tour of the Legend Wizard
The Legend Wizard provides an easy, quick way to add a legend to your map. The wizard allows you to
- Choose which map layers you want to be part of the legend.
- Set the number of columns in the legend.
- Create and symbolize a legend title.
- Create and symbolize a border and background for the legend.
- Customize the shape and size of legend patches.
- Set the spacing between legend elements.
When you first access the wizard, you will see the list of layers in your map that will make up the legend.
Not all layers need to be in the legend. You have the option to remove any of the layers listed. You can reorder the layer list as you see fit. This reordering does not affect layer ordering in the table of contents. This panel of the wizard also provides options to set the number of columns in the legend. The wizard does not provide options to determine where columns begin. You can further refine your columns by modifying the legend after it has been created using the options on the Items tab of the Legend Properties dialog box.
Click Preview to see what the legend will look like. Click the button again to remove the preview legend.
The next panel provides a place for you to enter a legend title.
Along with typing in the title text, you can choose the color, size, font, and justification of the text.
The next panel offers choices to customize a border, background, and drop shadow for the legend.
The next to last panel gives you the opportunity to set patch properties for line and polygon symbols.
Here, you can set the width, height, and shape of the patch for line or polygon features. For more information on working with patch shapes, see working with legend patch shapes.
The last panel allows you to specify the spacing between legend elements.
As you click each spacing input box, the spacing indicator (in red) in the image to the right will adjust to show you where the spacing will be adjusted.
Transparency in legends
If you have layers with transparency in your map, ArcMap simulates the transparent colors in your legend. When layers in a data frame are made transparent, the table of contents and the legends in layout view automatically use lighter colors to reflect transparency.
The option to simulate transparency in legends is set on the General tab on the Data Frame Properties dialog box. When this option is turned on, a layer drawn with solid, bright red polygons will appear in the legend as a light red or pink, depending on the percentage of transparency applied to the layer. However, with the simulate transparency option off, the legend will still show the solid red polygon symbol, even though the polygons don't appear red on the map because the layer is transparent.
In addition, you can convert the legend to graphics and manually specify the legend patch colors. Using the Eye Dropper tool, you can obtain the exact RGB value of a pixel and use that color for the legend patch.
Modifying legend properties
Using the Legend Properties dialog box, you can
- Change the wording, symbology, and position of the legend title.
- Change properties for patches.
- Change the reading orientation.
- Adjust the spacing between legend elements.
- Change the presentation style.
- Add or remove columns.
- Change text symbology for selected items.
- Determine the interactive behavior of the legend through its connection with the map.
The Legend Properties dialog box has four tabs—Legend, Items, Frame, and Size and Position.
The Legend tab provides a way to customize the legend title, legend patches, and the spacing between legend elements. You can also change the legend reading orientation if the language you are working in is bidirectional.
Currently, only one position for the title, above, is supported. You can convert the legend to graphics and rearrange legend components manually if you want to reposition the title. You can also choose not to include a title as part of the legend and create a title as an independent graphic element.
If you customize line or polygon patches on the Legend tab, the changes will be applied to all line or polygon symbols in your legend. If you want to override the patch shape for specific layers, use the legend item properties by right-clicking the legend item on the Items tab and selecting Properties. Then click the General tab on the Legend Item Properties dialog box.
On the Items tab, you can customize individual legend items, change text symbology, and adjust the legend behavior in relation to what's happening with the map.
To reorder one or more items in the legend, select them in the list and click the buttons for moving them up or down or to the top or bottom.
To change the text symbol used by some or all of the items, use the controls below the list. You can apply these changes to all the text associated with the selected item or items, or just to particular text items. These include the layer name, the heading, the label, and the description.
You can also modify all the text symbology in the legend at once by using the font controls on the Draw toolbar while the legend is selected in your layout.
Using this dialog box, you can control the number of columns in your legend. You do this by selecting from the Legend Items list the legend item you want to use to start a new column. Check the Place in new column check box. Then enter the number of columns you want to use for this legend item. Do this for each column you want in your legend.
The number of columns set in the Legend Wizard work on the entire legend. The number of columns entered on the Items tab of the Legend Properties dialog box is applied to a single legend item. This legend item may have many parts, for example, the legend item may represent cities broken into five classes based on population. Entering a number greater than the number of parts in the legend item will have no effect.
Four options are available to adjust the behavior of the legend based on changes made to the map.
- Only display layers that are checked on in the table of contents.
- Add a new item to the legend when a new layer is added to the map.
- Reorder the legend items when the map layers are reordered.
- Scale symbols when a reference scale is set.
You can choose to only display layers that are checked on in the table of contents. If a layer's visibility is turned off, it will automatically be removed from the legend. Otherwise, layers will be shown in the legend whether or not they are visible on the map. You can have the legend add a new item to the legend automatically when a new layer is added to the map. Another option is to reorder legend items automatically whenever the map layers are reordered in the table of contents. Finally, you can choose to scale symbols in the legend when a reference scale is set in the map. This will match the size of line and points symbols in the legend to the size of line and point symbols on the map. This only applies when the map has a reference scale. Without a reference scale set, the symbols in the map and in the legend will remain constant.
To change the legend item style, double-click the item listed in the Legend Items list box. This takes you to the Legend Item Selector dialog box.
You can also access the Legend Item Selector dialog box by clicking an item or selecting multiple items by using SHIFT or CTRL and clicking the Style button.
Here, you can select and preview the legend style you want to use for the chosen legend item. As you select an arrangement from the left, you will see a preview on the right. To make further modifications, click Properties. This brings up the Legend Item dialog box. Using this dialog box, you can further customize the arrangement and appearance of legend items.
The Arrangement tab provides six options for the arrangement of the patch, label, and description. The General tab allows you to hide, display, and change the text symbology of the layer name, labels, headings, and description. You can also override the default patch for line and polygon features.
Other options on the General tab include the ability to show classes from a specific heading if the layer has been divided under headings on the Symbology tab of the Layer Properties dialog box and to prevent items from being split across legend columns.
You can also access these properties by right-clicking the legend item on the Items tab and selecting Properties.
Finally, the dialog box contains two standard tabs for setting the frame (border and background) and the size and position of the legend.
Converting map elements to graphics
You might want to convert a map element, such as a legend, to graphics if you want more precise control over each item that composes the map element.
It is important to note that once you convert a map element into a graphic, it is no longer connected to its original data and will not respond to changes made to the map. For instance, with a legend element, if you decide to add another layer to the map after the legend has been converted to a graphic, the legend will not automatically update. It will have to be deleted and rebuilt again using the Legend Wizard. Therefore, it is a good idea to convert elements to graphics only after your map's layers and symbology are finalized.
The image below shows a legend that has been converted to a graphic.
You can further ungroup the legend graphics so the individual elements (the patches, text, and so on) that compose the legend can be edited individually.
How to change the number of columns in your legend
Though you can set the number of columns in your legend when you are first creating it using the Legend Wizard, you may find that you want to further refine your columns. You can do this using legend properties.
- Double-click the legend to bring up the Legend Properties dialog box.
- Select the layer from Legend Items that you want to start a column.
- Check the Place in new column check box.
- Repeat this for each additional layer in which you want to start a column.
Any values entered into Columns under the Legend Properties dialog box only affect the selected item. Do not use this control to define the number of columns for the entire legend. The total number of columns in the legend can be defined when first creating the legend in the Legend Wizard or by using the Place in new column check box outlined in the steps above.
How to change the properties for a single legend item
- Double-click the legend to bring up the Legend Properties dialog box.
- Click the Legend tab on the Legend Properties dialog box.
- Right-click the item from Legend Items in which you want to edit and click Properties.
- Make your changes using the Arrangement and General tabs.
How to turn on transparency simulation in your legend
- Right-click the data frame in the table of contents and click Properties.
- Click the General tab.
- Check the Simulate layer transparency in legends check box.
Optionally, uncheck the Simulate layer transparency in legends check box if you do not want transparency simulation in your legend.