Making Time Zones with Area Splits

This is a small, more sophisticated example that uses the Solvers - Topology - Split Objects solver to create new areas in a map and to then use Table View to copy data attributes into lots of small objects. The main focus is using Table View. For more examples of creating areas to split objects, see the Great Lakes case.

This example combines a number of intermediate techniques and is presented showing just the highlights. It shows some of the actual procedure used to create the manifold.net map of world time zones on the Free Maps and Data page of this web site. We simply made screen shots and took notes as we created this map. Click on the thumbnails to get bigger images.

This example jumps into the middle of the work with the map. It shows a lot of toolbars turned on as an advanced user might have them open.

	The map has already been chopped into various areas. Areas selected in red will now be split into a smaller areas. An overlying area in a dotted, transparent style will be used to "cookie cutter" the larger red areas. Basically, we wish to chop out an area in the shape of Manitoba's time zone from the larger mass of Canada. The Eastern provinces have already been chopped out.
	We use the Split Objects solver to split the red area. The solver uses the Selection as the object set (that is, the selected objects in red are those that are to be split). We've marked the dotted area as the splitting area (it's marked with small yellow flag). Hit OK and the solver goes to work. Note that we've selected multiple areas in red: the solver will automatically chop all the areas that are under the splitting area, just like a giant "cookie cutter."
	The red, selected areas have now been split into two areas: a new area has been created exactly under the splitting area, and the "rump" of the red area is still selected in red. The new area is seen in it's default, deselected color. We now want to take the newly created areas and give them the same time zone attributes as the Central time zone in the US below it. There's a fast way of doing this in Manifold.
	First, we hide the splitting area to get it out of the way. Next, we use Open Box select to select both the Central time zone area in the US as well as our newly created Manitoba area. We view the Selection in Table View and highlight all objects. Now, for the cool trick: if we CTRL-double-click into one of the edit boxes that contains a value and then hit Enter, all of the highlighted records for that field will get that value. In this shot we've just CTRL-double-clicked into the "Offset" field of the table. This is a standard Windows power move which is really nice to have in a GIS table view.
	Here's just the Table View after we've hit Enter. Note how the value has been propagated into both records.
	Deselecting to see the formatted color of the objects, we see that Manitoba has taken on the color specified by this thematic autoformat for objects of that time zone offset, the same color as the Central time zone in the US. However, we note that there are a zillion islands in the far north that have yet to be colored. We will do this by selecting all of them and then using our "CTRL-double-click" trick again in Table View.
	Use a rectangular Open Box select to select all the zillions of islands that are to be assigned to this time zone. Overlap the Manitoba area so it is selected too. Open the Selection Table View and push the Highlight All button to highlight all the records. CTRL-double-click into the attribute box containing the attribute to be propagated throughout all the highlighted records and press Enter. The screen shot shows the Table View just before we push Enter, after which all of the records will have that same value. We've dragged Table View open a bit in this illustration to show more records. This sure is a fast way to load lots of records with the same data attribute!
	Deselecting to get rid of the red color, we see that all of the islands have been given the desired data attribute. Note in this close view what a great job the Split Objects solver did in splitting lots of island areas at once.

In this example we first copied the data attributes from the US Central time zone to the big Manitoba area and then in a second step we copied the attributes into the smaller island areas. We could have done this in one step by selecting all the island areas as well as the Manitoba area at once.

However, in "real life" one often works at a larger zoom to work with bigger objects and only later does one notice that some smaller areas were overlooked. In that case, it's a simple matter to zoom in to a convenient scale and to then use a quick select, table view, CTRL-double-click to propagate desired attributes into all target areas.

This map also uses a very simple label style with label "clipping" turned off so that text labels will overlap. It shows a session in the middle of preparing a new map, before it has been beautified for presentation.

Like what you see? Now is the time to buy Manifold System and get all these capabilities for yourself. It's only $145 and it totally outperforms ancient systems from an earlier era. You get more power, better ease of use and a spectacularly driven engineering organization working to serve you better. While you are at it, why not order a copy of TIGER/Line 1997 as well? Visit the Manifold.net Online Store for a quick, easy, and secure purchase of Manifold products, or (in the US) call 800-556-5919 to order by telephone (9-5 PST).