Working with Vector Data

Shapefile

Geopackage

• open format
• multiple layers
• different geometries
• can contain vector and raster layers
• different coordinate systems

Geopackage

Geopackage: Roads

SQLite

SQLite

SQLite Connection

SQLite Land Use

Symbology

Color

Fill color

Symbol Structure

Stroke

No pen

Scale-based visibility

Buildings

Scale-based visibility

Scale-based visibility

Adding Symbol Layers and Ordering Symbol Levels

Roads

Add Symbol Layer

Order Symbol Levels

Ordered Symbol Levels

Geometry generator symbology

Water: Single Symbol

Water: To Centroid

Water: To Centroid

Water: 2 symbol layers

Classifying Vector Data

Why Classification?

• Summarizing the attribute value distribution
• Representing the spatial distribution of attribute values

Measurement Scales

• Nominal: name-based, no order
• Ordinal: arranged in order (ranks)
• Interval: pos, neg, zero values (height above/below sea level)
• Ratio: positive, zero values (distances, degrees Kelvin)

Classifying Nominal Data

SCAG Data: COUNTY

Ratio/Interval Classification

TOTPOP

ACRES

Extensive and Intensive Variables

• AREA and TOTPOP are counts
• Extensive variables
• Geometry size correlated with values
• Choropleths generally not appropriate for extensive variables

Intensive Variables

• Percentages, ratios, densities
• Standardized by area (in some sense)
• Geometry size not correlated with values
• Choropleths appropriate for intensive variables

pctHISP (Equal Interval)

pctHISP (LA Equal Interval)

pctHISP (LA Quantiles: 5)

pctHISP (LA Jenks: 5)

pctHISP (LA Standard Deviation)

pctHISP (LA Pretty Breaks)

mapclassify

Color

ColorBrewer

ColorBrewer in QGIS

Next Up

• Creating Vector Data