Working with Geospatial Data

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# Working with Geospatial Data
## GIS and Shapefiles
### Ben Baumer
### SDS 192</br>April 10th, 2020</br>(<a href="http://beanumber.github.io/sds192/lectures/mdsr_geo_05-shapefiles.html" class="uri">http://beanumber.github.io/sds192/lectures/mdsr_geo_05-shapefiles.html</a>)

---

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# GIS

---
## Geographic Information System (GIS)

.centered[![](http://www.in.gov/gis/images/Capture9.PNG)]

---
## [Smith Spatial Analysis Lab](http://www.science.smith.edu/sal/)

.footnote[http://www.science.smith.edu/sal/]

.centered[![](http://www.science.smith.edu/sal/wp-content/uploads/sites/13/2015/03/Banner980x190_1.png)]

- Jon Caris, Director

- Tracy Tien, Spatial Data Specialist

- Smith-specific data

---
## ArcGIS: Proprietary GUI

.footnote[https://www.arcgis.com/]

.centered[![](https://www.arc2earth.com/wp-content/uploads/2014/05/basemaps_sandiego_airports2.png)]

---
## QGIS: Open-source GUI

.footnote[https://www.qgis.org/]

.centered[![](https://www.qgis.org/en/_static/images/about-screenshot.png)]

---
## Spatial packages in R

- Working with shapefiles
    - ~~`sp` for classes and basic functionality~~
    - ~~`rgdal` for projections and advanced reading/writing~~
    - ~~`rgeos` for spatial computations~~
    - `sf` for everything

- Plotting
    - ~~`ggmap` for static maps~~
    - `ggplot2` for static maps
    - `leaflet` for interactive maps

---
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# Shapefiles

---
## Shapefiles aren't really files

```r
library(sf)
biketrails_dir <- here::here("biketrails/biketrails_arc/")

biketrails_dir
```

```
## [1] "/home/bbaumer/Dropbox/git/sds192/biketrails/biketrails_arc/"
```

```r
list.files(biketrails_dir)
```

```
## [1] "Bicycle_Trails.lyr"     "biketrails_arc.cpg"     "biketrails_arc.dbf"    
## [4] "biketrails_arc.prj"     "biketrails_arc.sbn"     "biketrails_arc.sbx"    
## [7] "biketrails_arc.shp"     "biketrails_arc.shp.xml" "biketrails_arc.shx"
```

- Shapefiles have extension `.shp`

- all these files store different information

- you need *all* of them!

---
## `sf` `data.frame`s

```r
biketrails <- st_read(biketrails_dir)
```

```
## Reading layer `biketrails_arc' from data source `/home/bbaumer/Dropbox/git/sds192/biketrails/biketrails_arc' using driver `ESRI Shapefile'
## Simple feature collection with 272 features and 13 fields
## geometry type:  MULTILINESTRING
## dimension:      XY
## bbox:           xmin: 42526.52 ymin: 794291 xmax: 328921.5 ymax: 957916.8
## proj4string:    +proj=lcc +lat_1=41.71666666666667 +lat_2=42.68333333333333 +lat_0=41 +lon_0=-71.5 +x_0=200000 +y_0=750000 +datum=NAD83 +units=m +no_defs
```

```r
biketrails
```

```
## Simple feature collection with 272 features and 13 fields
## geometry type:  MULTILINESTRING
## dimension:      XY
## bbox:           xmin: 42526.52 ymin: 794291 xmax: 328921.5 ymax: 957916.8
## proj4string:    +proj=lcc +lat_1=41.71666666666667 +lat_2=42.68333333333333 +lat_0=41 +lon_0=-71.5 +x_0=200000 +y_0=750000 +datum=NAD83 +units=m +no_defs 
## First 10 features:
##    TRAIL_STAT        OWNER          PREV_OWNER   MANAGER STATUS_OWN STATUS_MAN
## 1           A         <NA>                <NA>      <NA>       <NA>       <NA>
## 2           A         <NA>                <NA>      <NA>       <NA>       <NA>
## 3           A         MBTA                 B&M  STONEHAM          S          M
## 4           A         EOTC        Penn Central      <NA>          S       <NA>
## 5           A         EOTC        Penn Central      <NA>          S       <NA>
## 6           U Chatham/Pvt.        New Haven RR      <NA>       <NA>       <NA>
## 7           E    Cambridge                <NA> Cambridge          M          M
## 8           E       Boston             Conrail    Boston          M          M
## 9           E      Bedford Billerica & Bedford   Bedford          M          M
## 10          C          CSX    New York Central      <NA>       <NA>       <NA>
##                             TRAILNAME                LINENAME
## 1                                <NA>                    <NA>
## 2                                <NA>                    <NA>
## 3                                <NA>         STONEHAM BRANCH
## 4                                <NA>      RANDOLPH SECONDARY
## 5                                <NA> E BRIDGEWATER SECONDARY
## 6         Cape Cod Rail Trail/Chatham Cape Cod/Chatham Branch
## 7  Community Path over Gilmore Bridge                    <NA>
## 8                East Boston Greenway                    <NA>
## 9             Narrow Gauge Rail Trail     BILLERICA & BEDFORD
## 10              Cochituate Rail Trail       Saxonville Branch
##                               CONTACT1
## 1                                 <NA>
## 2                                 <NA>
## 3                                 <NA>
## 4                                 <NA>
## 5                                 <NA>
## 6              http://www.cctrails.org
## 7           http://www.pathfriends.org
## 8                  http://www.tpl.org/
## 9         http://www.bedforddepot.org/
## 10 http://www.millermicro.com/crt.html
##                                     CONTACT2 OPENED COMPLETED SHAPE_LEN
## 1                                       <NA>      0         0 2682.1488
## 2                                       <NA>      0         0 3185.2858
## 3                                       <NA>      0         0 1023.9954
## 4                                       <NA>      0         0 3539.2376
## 5                                       <NA>      0         0 3179.0013
## 6  http://www.state.ma.us/dem/parks/ccrt.htm      0         0 6630.1329
## 7             http://www.ci.cambridge.ma.us/   1970      1970  558.3535
## 8                                       <NA>   2001         0 1139.0108
## 9             http://www.town.bedford.ma.us/      0         0 4906.9525
## 10              http://www.framinghamma.org/      0         0 1535.4054
##                          geometry
## 1  MULTILINESTRING ((155011.7 ...
## 2  MULTILINESTRING ((152703.3 ...
## 3  MULTILINESTRING ((236337.8 ...
## 4  MULTILINESTRING ((240197.2 ...
## 5  MULTILINESTRING ((244758.8 ...
## 6  MULTILINESTRING ((322333.3 ...
## 7  MULTILINESTRING ((235460.3 ...
## 8  MULTILINESTRING ((238231.9 ...
## 9  MULTILINESTRING ((218391.3 ...
## 10 MULTILINESTRING ((210189.7 ...
```

---
## Where to find shapefiles?

- Include `gis` or `shapefile` or `.shp` in your Google search

- Lots of government websites:
    - [MassGIS](https://docs.digital.mass.gov/dataset/massgis-data-layers)
    - https://www.data.gov/geospatial/

- Other R packages:
    - [tigris](https://github.com/walkerke/tigris)
    - [tidycensus](https://github.com/walkerke/tidycensus)