Welcome to Methods 3, Lecture 4
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Methods 3
(review)
Choropleth?
source
Louisiana Loses Its Boot
"Using publicly available data, [we] created a map on which areas that commonly appear as land on government issued maps—woody wetlands, emergent herbaceous wetlands and barren land—were re-categorized to appear as water."
the modifiable areal unit problem
source
"One-third of all homes with a Flint ZIP code lie outside the city. Thus, the state’s numbers for Flint were watered down by an additional 50 percent of addresses that weren’t in the city and weren’t using Flint water."
source
Dani
Moja
let's talk about project thoughts
you should almost never make choropleths with just counts
think about ways to normalize your data
this makes the data comparable across regions
duplicating layers
you can copy and paste styles
you can save a layer with its style
insets
selecting features
QGIS has a few way to select features
QGIS has a few way to select features
QGIS has a few way to select features
QGIS has a few way to select features
- by hand
- by location
- by expression
by hand (selection tools)
select by location
write an expression on the left
field name in quotes
"availableB"
use typical comparison operators with numbers
"availableB" < 10
when comparing text, always put the text in single quotes
when comparing text, always put the text in single quotes
"stationNam" = 'Willoughby Ave & Hall St'
selecting data and exporting as a new shapefile is one way to isolate data
keep your file names descriptive
always click this button to select a destination
a GIS will let you:
- visualize map data
- create and edit map data
- overlay map data
- analyze map data
Geoprocessing
buffers
buffers
make a "buffer" around features
well, why?
you can make negative buffers
clipping
overlay operations
Intersect
Union
usually you'll use geoprocessing functions in a chain
keep track of these as you work!
joins
joins
...continued next week