Introductions

About the instructor

• Academic: http://personal.tcu.edu/kylewalker/
• Consulting/blog: http://walkerke.github.io/
• Twitter: https://twitter.com/kyle_e_walker

Mapping Immigrant America

Data

• The information component of GIS
• Example: Texas county data in Excel spreadsheet

Geographic data

• Geographic data includes reference to position on Earth’s surface
• Example: Tarrant County

Geographic data

GIS data displayed as layers

Image source: Wexford County, MI

Data models: abstraction of reality

Types of GIS data

• Vector data: used to represent discrete geographic features
• Examples: cities, lakes, roads
• Raster data: used to represent continuous geographic phenomena
• Examples: imagery, elevation, temperature

Vector data

• Coordinate pairs form points, lines, and polygons

Points: Large cities in Texas

Lines: Interstate highways

Polygons: Counties

US counties in 1880

Attribute data in a GIS: the table

Rows and columns

Joins

Types of joins

• Inner join: only the matching rows are retained
• Outer join: all rows are retained, regardless of the presence or absence of a match between source and target tables
• Left (outer) join: all rows in the source table are retained

Inner vs. outer joins

Joining shape and tabular data

Queries

• Records can be accessed within databases through the use of queries
• Queries commonly used to subset data based on a given set of desired attribute values

Structured Query Language (SQL)

• Common language for querying databases

Example SQL statement:

SELECT * FROM Texas_counties WHERE "Total" > 100000

• Used in ArcGIS to select and subset data

Boolean operators

• Used to define multiple criteria in a selection query
• AND: Selects records where both criteria are met
• OR: Selects records where at least one of the criteria are met
• NOT: Restricts selection to records that do not satisfy a specified criterion
• XOR: Selects records where one, but not both, of the criteria are met

Querying our data

Choropleth maps

Dot-density

Source: Radical Cartography

Designing a map: key considerations

• What are you mapping?
• Who is your audience?
• In what format will you be presenting the map?

Visual variables in cartography

Color selection

• Hue: color, commonly understood (red, blue, green)
• Lightness or Value: extent to which color is light or dark
• Saturation: vividness of the color

Image source: Wikipedia

Color selection

Source: Brewer, Designing Better Maps

Color selection

• What does your color choice say to the map reader?

Source: Brewer, Designing Better Maps

Styling our immigration map

Layout and map elements

Visual hierarchy of map elements

Source: Brewer, Designing Better Maps

Cartography and the basemap

Source: Kenneth Field, Cartonerd

Cartography and the basemap

Source: Kenneth Field, Cartonerd

Creating our map layout