2. Show and hide multiple point, line and area layers
Clicking
"Education", "Health Care", "Government",etc. in the left frame will display a list of point layers in this category; clicking "Roads" will display line layers, and "Shopping Centers" will let you access polygon layers defined for this map. Check the box to the left of a layer's name, and the layer will display on
the map, while the layer's symbol will show up next to the layer's name. Click a name of a point layer to see an associated table of attributes.
Once a layer is displayed for the first time, turning it on and off will work
very fast, since the layer's XML file will be by now cached on the client
browser. Note that turning layers on or off doesn't cause map redraw, unlike in
many common desktop GIS.
3. Jump to URLs associated with geographic objects
Click "Education" to display names of point layers in this category. Place a checkmark next to "Elementary Schools", and see how this layer get displayed on the map. You can now position the
mouse pointer on a school symbol, and click the left mouse button. If the school has an associated URL (in the status bar, you will see "Click to open URL"), a new browser window will
open and display a Web page for that school. You can associate URLs with any point symbols, as well as with area on your map: simply have an additional column in your GIS data file (shapefile, for
example), that is called "URLs", or similar.
4. Display names of neighborhoods, point, line and area objects
Position
the mouse within a neighborhood area, and the neighborhood name will show up. If you are looking at
spatial distribution of some attribute you have selected, positioning the mouse
within an area will also display the value of the attribute for that area.
If you position the mouse over a point, line or area object, this object's label will also appear. You can stick the labels to the map by clicking the object you wish to label while holding the CTRL key.
If you prefer to remove area labels that initially appear on the map, remove checkmark next to "Labels" under the "Settings" button.
5. Manipulate zoom level and positioning
When you
load the map for the first time, it responds to mouse clicks on a map by opening
a particular URL. However, if you click on any of the three radio buttons
"zoom in", "pan", or "zoom out", the map response
to mouse clicks will change. If "zoom in" is selected, clicking
anywhere on the map will recenter the map at the point where you clicked, and
zoom in, enlarging the area by two times. "Zooming out" will recenter
the map with the opposite effect, while "panning" will simply recenter
the map without changing scale. Notice that the status bar is displaying
latitude and longitude of your mouse as you move it. You can switch back to the
"Open URL" mode by clicking this radio button on the left frame.
6. Simple and composite queries
Click the Query button, and the left frame will expand to show a query dialog.
You can build simple queries with just a few mouse clicks. For example, to display neighborhoods with 1999 Crime Index over 500, map this variable, and then construct the query in the form
[Current var] > 500
To build this query expression, you can click in the operation sign, and then type in the value. Click the Info button to get information about the current variable, which will assist you in composing the query.
Make sure you are selecting a New Set, and click Evaluate: the map will now
highlight areas that satisfy the query. If you now click the Info button, it
will display the query and selection information. Clicking Listing will display
currently selected records as a table. You can "View Source" of this table and save it for subsequent editing in Excel or another spreadsheet program.
Composite queries are essentially
a sequence of simple queries. Once your first simple query selected several
records, you can select from, or add to this selection set, using variables from
the same or a different dataset, as well as derived variables. All you need is
to map another variable, and choose "Select from set" or "Add to
set" before clicking "Evaluate".
7. Displaying buffers around
points
Click anywhere on the map while holding the ALT key, and a
circle centered on the spot where you clicked, will be drawn. You can specify
the radius and color of the circle under "Settings". Note that this is
a buffer of a given radius, and it won't have a perfect circular shape on this
map (because this map is in un-projected latitude-longitude).