Fundamental Graphs

When we are given a dataset, we must determine:
  1. 1.
    What to visualize i.e. select and transform
  2. 2.
    How to visualize it i.e. choose/design a representation
This section describes various fundamental graphs that can be used to visualize data, including:
  • Bar Charts
  • Scatter Plots
  • Matrix
  • Line Charts
  • Symbol Maps
These fundamental graphs are widely adopted, effective and useful. They solve a very large percentage of visualization problems, and serve as a good training ground for more sophisticated graphs.

Bar Chart

A bar chart is used to represent how a quantity distributes across a set of categories.
Every bar represents a category and the height of each bar denotes the quantity.
Therefore, it is suited for 1 Categorical/Ordinal attribute (on the X axis) and 1 Quantitative attribute (on the Y axis).

Line Chart

A line chart is used to visualize how a quantity changes in relation to another quantity (typically time).
Therefore, it is suited for Temporal and Quantitative attributes on the X and Y axes respectively.

Scatter Plot

A scatter plot is used to visualize how a quantity relates to another quantity.
Therefore, it is suited for Quantitative and Quantitative attributes on the X and Y axes respectively.

Matrix

A matrix can be used to visualize how a quantity distributes across two categories. Note that the sizes of the squares are proportional to the quantities.
Therefore, it is suited for 2 Categorical (or Ordinal) attributes and 1 Quantitative attribute (in the cells).

Symbol Map

A symbol map is used to visualize how a quantity distributes across two spatial coordinates. Note that the sizes of the symbols (colored areas) are proportional to the quantities.
Therefore, it is suited for Spatial and Quantitative attributes.