Map tool - an introduction

MAPPING TOOL HELP

The Mapping Tool is a simple, yet powerful, way to create maps of data in the system.

There are several ways to start a new map. You can choose to map any dataset, which will start a map with that dataset loaded. You can also base a new map on an existing snapshot, or create a map using multiple datasets at once from a collection.

If you base a map on a snapshot, rules will be defined for you that match those used in the snapshot. Otherwise, if any of the starting datasets have default styles defined, those will be used. Most often, however, you will simply see a blank map, and a single empty rule for your dataset.

You can pan and zoom the map. To pan it, select the "Move" tool on the map toolbar, and grab the map and drag it. To zoom in or out, click on either one of the magnifying glass icons, or on the zoom level indicators between them. You can also "drag zoom" by selecting the "Zoom" tool and then dragging a box on the map. The map will zoom to fit the box you drew.

You can change the visible size of the map by grabbing the "Resize" area of the map toolbar and dragging it down.

You can change the background style of the map by selecting one of the three available styles on the right side of the map toolbar. (Note that snapshots do not currently preserve the background style of the map.)

To show data on the map, you must define a style rule. Style rules control how the records in the dataset are displayed on the map. Raster datasets don't have rules: they are always simply displayed as-is.

To define a rule, first you must choose the attribute of the dataset that you want to display. (If you want more information about the definition of an attribute, click the info button next to the attribute dropdown.) After you've selected an attribute, the rest of the rule will display. For quantitative attributes (like numeric ranges), you will have several options that we will look at shortly. For categorical attributes (like names), you will only be able to color the records by unique value. You can select one of several pre-defined palettes. Once you have picked a palette, the rule is completely defined, and the "Refresh Map" button will be highlighted. Click it to draw the map. Once the map is drawn, a list of color/value choices will be shown beneath your visualization rule. You can change the color choices by clicking on the color you wish to change.

If the attribute is quantitative, you have more options. You can choose "all unique values", which we've already discussed, but you can also choose graduated spectrum, linear spectrum, between, equals, above, or below. Let's look at each in turn.

Graduated spectrum

This option lets you define a fixed number of buckets called "quantiles." Each bucket will have an approximately equal number of records in it, though the values those records span may vary widely. Each bucket gets assigned a color from a range defined by the rule. You can set the starting and ending points of that color range by clicking on the colors. When you are ready, click the "Refresh map" to display the results. Just like the "all unique values" option, you can edit the color of a particular bucket directly after the map is drawn, by clicking on the color of the value range you want to change.

Linear spectrum

This option simply assigns a color from the color range to a record based directly on the value of the attribute. You change the end points of the color range by clicking on the colors.

Between

Assigns a specific color to records that fall between two specific values. You can change the color by clicking on it.

Equals

Assigns a specific color to records that equal a specific value. You can change the color by clicking on it.

Above

Assigns a specific color to records that fall above a specific value. As usual, you can change the color by clicking on it.

Below

Assigns a specific color to records that fall below a specific value. As usual, you can change the color by clicking on it.

You can add additional rules to a dataset by clicking the blue add button to the right of the rules. You can change the drawing order of rules by clicking on the up and down arrows on the grey handle on the right of the rule. You can temporarily hide a rule by clicking on the checkbox next to it to the left.

You can add additional datasets by using the "Search for More Datasets" button at the bottom of the tool. This will bring up an empty search box. You can add, remove, and edit search criteria just like the main search tool. Press the search button to run the search. If you see a result item you would like to add, click the add button next to it.

You can also add datasets from your library drawer on the left hand edge of the window. Click on it to expose the drawer, then use the "Show" menu to show all the datasets in your library, or datasets from a particular collection, or the results of your most recent search. Use the add button next to the dataset items to add them.

You can remove a dataset from your map by clicking "Remove" in its action menu. You can move all of its drawing rules up and down relative to the other datasets by clicking the up or down arrows on the grey handle to the right of the dataset name.

If you need to save your map session for later, choose "Keep session in library" from the action menu in the upper right. This will add this session to the "working sessions" of your library, so you can come back to it later and keep on working.

If you are ready to make a snapshot of your session, choose "Create snapshot" from the action menu in the upper right. This will create a snapshot of your map as it is at that moment. You can continue to work, and make multiple snapshots.

You can also examine the legend as you go. Click on the drawer tab on the right edge of the map tool to slide it out. This legend will be visible on any snapshots you create.