geographic data?
smnorris opened this issue · comments
Many geo data issues are already covered in in other sections - especially the entered by humans part - but there are some common quirks that might be worth mentioning?
- lon/lat vs lat/lon
- inconsistent or incorrect CRS
- inconsistent values used to indicate NULLs
A gotcha for me with was different names used to refer to same city (Beijing vs Peking), or different ways to name the same country (China vs People's Republic of China), I end up needing to create new columns and bind the varied names to standard country codes before I can join them.
What does CRS stand for? @smnorris
sorry - CRS / SRS / Projection.. many names for basically the same thing.
basic - http://mapschool.io/#projection
more - https://en.wikipedia.org/wiki/Geographic_coordinate_system
Most common tends to be the mystery CRS, where it isn't specified in the data/metadata and the user has to guess which one to use. Really fun is when a dataset has some records in one CRS, some in another... and the lucky user gets to figure out which is which.
+1 to this.
I'd also add - geometry has already been simplified. A fantastic demo is at https://www.jasondavies.com/simplify/