Week 1 - Visualization in Tableau

Analysis and Design, Chapter 1 & 2, Tamara Munzner

Data Types

An attribute is some specific property that can be measured, observed, or logged.

An item is an individual entity that is discrete, such as a row in a simple table or a node in a network.

A grid specifies the strategy for sampling continuous data in terms of both geometric and topological relationships between its cells.

A position is spatial data, providing a location in two-dimensional (2D) or three-dimensional (3D) space.

Dataset Types

A dataset is any collection of information that is the target of analysis. The four basic dataset types are tables, networks, fields, and geometry; other possible collections of items are clusters, sets, and lists.

Tables

In a simple table of orders, a row represents an item, a column represents an attribute, and their intersection is the cell containing the value for that pairwise combination.

A multidimensional table has a more complex structure for indexing into a cell, with multiple keys.

Networks and Trees

The dataset type of networks is well suited for specifying that there is some kind of relationship between two or more items. An item in a network is often called a node. A link is a relation between two items.

A synonym for networks is graphs.

A synonym for node is vertex.

A synonym for link is edge.

Networks with hierarchical structure are more specifically called trees. In contrast to a general network, trees do not have cycles: each child node has only one parent node pointing to it. One example of a tree is the organization chart of a company, showing who reports to whom.

Fields

The field dataset type also contains attribute values associated with cells. Each cell in a field contains measurements or calculations from a continuous domain: there are conceptually infinitely many values that you might measure, so you could always take a new measurement between any two existing ones. Continuous phenomena that might be measured in the physical world or simulated in software include temperature, pressure, speed, force, and density; mathematical functions can also be continuous.

In contrast, the table and network datatypes discussed above are an example of discrete data where a finite number of individual items exist, and interpolation between them is not a meaningful concept.

Geometry

The geometry dataset type specifies information about the shape of items with explicit spatial positions. The items could be points, or one-dimensional lines or curves, or 2D surfaces or regions, or 3D volumes.