additional things to add to sf tutorial

[jamiecmontgomery]

some functionality I want to add to the sf tutorial:

• st_as_sf
• Combining two separate simple feature objects
• Aggregating geometries (e.g. https://r-spatial.github.io/sf/articles/sf4.html#aggregating-or-summarizing-feature-sets)

[jamiecmontgomery]

I think we should swap the order in which we show the two AK shapefiles and present the one in EPSG 4326 first:

and then use st_transform to get it into the nicer looking one here so we don't have to transform back when we plot later on

[jamiecmontgomery]

eh nevermind I realize when we're doing the join to population data, we need latlong so ignore previous comment

[jeanetteclark]

I agree with you I'm going to switch it all around

[jeanetteclark]

for next time:

• add more intro to what we are doing in the beginning (maybe show final ggplot map as a teaser?)
• introduce st_simplify and explain how it can be useful (especially for people with slow computers!)
• maybe explain a little bit about what a vector layer is and what geometries are for super spatial newbies