Welcome to Methods 3, Lecture 5
This is a web page that can be viewed as slides.
→ to move forward
← to go back
Methods 3
clipping?
attribute joins?
Kevin
Grace
project proposals due next week
managing files
make a folder for each thing you work on
come up with a per-project organization scheme
keep your data together
and name the files appropriately
labels
further reading:
spatial joins
spatial joins
when you have layers that both have geographic features
Works best when you have:
- polygons that don't overlap (such as school districts or census tracts) and
- points or smaller polygons that fall within them
geocoding
"I have this spreadsheet I want to map..."
"...it has addresses but doesn't have coordinates"
geocoding is a business
Google's geocoding terms:
up to 2,500 geocoding requests per day
Google's geocoding terms:
If you're using it online, "The Geocoding API may only be used in conjunction with a Google map..."
source
Yahoo's geocoding terms:
up to 2000 geocoding requests per day
Yahoo's geocoding terms:
"You must not store any results"
source
watch out for the "null island" effect
if geocoders can't find a location, they sometimes default to the middle of the country/state
source
sometimes if geocoders really have no clue, they give 0,0
source
what about going from a point → name of location?
"Never mind so-called disputed places (Kashmir, the West Bank, Cyprus, etc.) all neighbourhoods are 'disputed' around the edges..."
"... Our experience has been that there are few better ways to pick a fight than to tell someone what neighbourhood they are in (and being wrong)."
Aaron Straup Cope
heatmaps
heatmaps attempt to show probability over an area
source
heatmaps look at the covered area as a raster made of pixels
source
there are a variety of methods for giving values to pixels