Nominal data

As explained in D3.js in Action, Third Edition

A nominal value is a categorical value whose labels have no inherent ordering.

Nominal data is qualitative, nonnumerical data whose labels have no inherent order. City names and gender identity labels are nominal; unlike ordinal values, they cannot be ranked by magnitude. section 3.1.2

Use the data type to guide visualization decisions:

• Represent nominal categories with categorical colors rather than sequential or diverging palettes, which suit ordered values. section 3.1.2
• Classify attributes before choosing visual channels; qualitative data can also use patterns, symbols, connections, or enclosure. section 14.2
• Select D3 scales appropriate for qualitative data instead of treating nominal categories like quantitative values on a linear scale. section 3.1.2

A visualization planning exercise

List every dataset attribute, mark each as quantitative or qualitative, and brainstorm an encoding for the main attributes. A city-name field can become categorical color or another qualitative channel, while numerical fields may use position, length, area, or angle. section 14.2

Figure 3.4 A classification of data types

Use the data-type classification to distinguish nominal and ordinal qualitative values from discrete and continuous quantitative values. section 3.1.2

How D3.js in Action, Third Edition covers it

How deep it goes

Defines unordered qualitative labels and gives encoding guidance, while deferring detailed scale treatment.

Examples

Uses gender identity labels, city names, countries, and a dataset-attribute classification exercise.

What you can do after

Apply it via D3 scales and categorical visual channels when planning a visualization.

How it connects

Links nominal data to qualitative data, ordinal data, D3 scales, and categorical color scales.

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Also explained in

• 

  liveBookmanning.com
  Ensemble Methods for Machine LearningA nominal feature is a categorical feature whose categories have no inherent ordering or quantitative relationship.
• 

  liveBookmanning.com
  Data Storytelling with Altair and AINominal data contains categorical labels whose values have no intrinsic ordering.
• 

  liveBookmanning.com
  Data Without LabelsNominal data consists of categories with no inherent ordering or sequence.

Compare how 4 books explain nominal data →

Related concepts

• data typekind of · A data type classifies values and specifies their representation or interpretation and the operations applicable to them.
• categorical datakind of · Categorical data consists of values representing membership in a discrete set of named or ordered categories rather than measured numerical magnitudes.
• qualitative datakind of · Qualitative data is descriptive, nonnumeric information representing characteristics, categories, meanings, experiences, opinions, or context rather than measured quantities.
• datakind of · Data is represented information, observations, measurements, or other values that can be stored, processed, transmitted, analyzed, or interpreted.

This explainer was generated by Manning's knowledge graph from the text of D3.js in Action, Third Edition. The section links point to the parts of the book it draws on.