Applicability and Functionality

Treemaps is a general concept and can be applied to many different kinds of data sets without a required field of an area. For example: a treemap of all the major TV stations in USA with information about the best shows, the amount of audience reached, ratings info etc will help a major corporation to reach a target audience in a marketing campaign. Similarly, a treemap with information on the elements of a periodic table, their size, reactivity, rate of reaching ionic state, reactivity with water etc will help scientists in developing various kinds of pharmaceutical products.

Nodes of Importance

Treemaps convey nesting and grouping in the same fashion as Venn diagrams. The nesting process is done to give treemap a more viewable structure and to give the user an ability to understand the nodes contained in a particular node. Nesting offsets are used for naming purposes of the nodes. They also give users control over the allocation of display space between internal and leaf nodes. The amount of an offset is directly proportional to emphasis on internal nodes and hence the structure of the hierarchy. If leaf nodes are the primary concern than smaller offsets should be used. Without any offsets only leaf nodes are visible and are probably suitable for certain applications. Small offsets give more display space of leaf nodes.

Sizing and Colors

There are certain generic tools available with most of the Treemap implementations. Most of the Treemap implementations come with a sizing attribute that is used to represent nodes of higher importance with greater space on the displayable area. Similarly, nodes are colored based upon another attribute that is selected by the user and the colors are either discrete or continuous.

Discrete coloring involves assigns a concrete color to every node available. For example, all nodes with the same ID are red. This type of coloring is applicable only in certain conditions. For example, in a movie treemap, a node representing a movie, all movies directed by Steven Speilberg are green color. This example makes sense and is probably a good application to use. For example, discrete coloring for every value of a stock, which range from-$4 - $800, is probably a bad idea and a lot of overhead to maintain and display.

Continuous coloring is done based upon choosing the lower and upper limits of a color or by choosing a scale of colors. For example, a basketball player with more number of triple pointers can be displayed with a darker shade than a player with little number of triple pointers. Similarly, a base color chosen for lower limit, mid range color for the average and a high range color for upper limit. The nodes with this kind of coloring will be colored in a continuous scale. For example, percentage change in volume sold of a stock on a particular day can range from red to green based upon the value of the percentage change.

Dynamic Queries

Dynamic query gives the user an ability to support display area filtering from nodes of relatively lesser importance and uses the captured space for nodes of relatively higher importance. This is relatively the easiest way to generate queries rather than using command line or form based queries.

Formulating dynamic queries provide the user with continuous and reversible feedback through the display area. The dynamic query filters consists of different kind of visual widgets like range sliders etc. used to create requests, replacing the usual commands prompt or form based querying.

Dynamic query filters allow an easy interpretation of many types of queries. Dynamic queries also prevent the possible typing errors and prevent the hassle to create complex SQL queries. With dynamic queries, the query is represented by a number of widgets. Every double slider consists of a label, a changing field indicating its current value, a slider bar with a drag box and a value at each end of the slider bar indicating minimum and maximum values.  

Above is a double slider whose label is ID, with minimum and maximum values 1 and 824 respectively. After a query, the current display area contains nodes ranging from 239 to 705.