{ps50sr}

• About
• Installation
• Fetching Data
• Launching {shiny} Apps
• Launching {plumber} Web API
• Docker Deployment

About

{ps50sr} is a repository for the applications and tools developed by this author for an interview with the Council of State Government Justice Center.

In essence, this package is centered around the data found on the “50-State Report on Public Safety” website. The data sets used to create dynamic visualizations on “Past 1, Strategy 1: Use data to understand crime trends” was downloaded, reshaped and stored as a portable .sqlite database to serve as the backbone to this demonstration. For more information on how the data was procured and saved, please look at the documentation on the repo: docs/data-pulling/*.

Installation

The R installation can be accomplished using {remotes}:

if(!requireNamespace("remotes")) install.packages("remotes")
remotes::install_github("cjcallag/ps50sr")

With the package installed, you can proceed to use the functions either loading the library (library(ps50sr)) or via the namespace (escaexplorer::).

Fetching Data

Load library:

library(ps50sr)

Once you install and launch the package, you may access to the portable .sqlite database of state crimes and arrests data as a system file within {ps50sr} package. First, you will need to establish a connection to this portable database. Note that you will need the {RSQLite} and {DBI} packages to establish that connection:

con <- DBI::dbConnect(drv = RSQLite::SQLite(),
                      ps50sr:::.sys_file("extdata/ps50sr.sqlite"))

With the connection established, you may proceed to query data:

res <- ps50sr::fetch_table(conn = con, table = "arrests", 
                           # Coerce data.frame to data.table by reference
                           dt = TRUE,
                           # Print SQL query to console
                           verbose = FALSE)
head(res)

##         State Abbrev Variable Value             Type
## 1:    Alabama     AL     2007   336 homicide-arrests
## 2:     Alaska     AK     2007    39 homicide-arrests
## 3:    Arizona     AZ     2007   297 homicide-arrests
## 4:   Arkansas     AR     2007    60 homicide-arrests
## 5: California     CA     2007  2022 homicide-arrests
## 6:   Colorado     CO     2007   109 homicide-arrests
##                                                                                               URL
## 1: https://50statespublicsafety.us/app/themes/50state/data/arrests-dashboard/homicide-arrests.csv
## 2: https://50statespublicsafety.us/app/themes/50state/data/arrests-dashboard/homicide-arrests.csv
## 3: https://50statespublicsafety.us/app/themes/50state/data/arrests-dashboard/homicide-arrests.csv
## 4: https://50statespublicsafety.us/app/themes/50state/data/arrests-dashboard/homicide-arrests.csv
## 5: https://50statespublicsafety.us/app/themes/50state/data/arrests-dashboard/homicide-arrests.csv
## 6: https://50statespublicsafety.us/app/themes/50state/data/arrests-dashboard/homicide-arrests.csv

The fetch_table() function is essentially a wrapper enabling the user to query an SQL database. As such, additional arguments can be passed in order to refine these queries.

res <- ps50sr::fetch_table(conn = con, table = "arrests", 
                           # Coerce data.frame to data.table by reference
                           dt = TRUE,
                           # Print SQL query to console
                           verbose = FALSE,
                           # Additional query arguments
                           where = "State = 'California' AND Variable = '2017'")

# Remove URL column from print
res[, -c("URL")]

##         State Abbrev Variable  Value             Type
## 1: California     CA     2017   1499 homicide-arrests
## 2: California     CA     2017   2561     rape-arrests
## 3: California     CA     2017  16942  robbery-arrests
## 4: California     CA     2017  88115  assault-arrests
## 5: California     CA     2017 212025      drug-arrest
## 6: California     CA     2017 666464 non-index-arrest

Launching {shiny} Apps

The {shiny} application(s) included in this package can be launched programmatically using the launch_app() function. At this time, the only valid {shiny} application included is ps50sr-dashboard which can be launched like so:

ps50sr::launch_app(app = "ps50sr-dashboard",
                   use_browser = TRUE)

By default the function uses the “0.0.0.0” as the default IPv4 address and TCP port 3838. However, these parameters can be modified through the function’s arguments. For more information, look at the documentation, ?escaexplorer::launch_app.

Launching {plumber} Web API

In addition to HTML applications, this package contains a web API that extends the functionality of the functions in this this package.

ps50sr::launch_api(port = 591, docs = FALSE)

With the API running you can visit this URL using a browser or a terminal to run your R function and get the results. For instance, http://localhost:591/echo?msg=hello will echo back the ‘hello’ message you provided. Here a Mac terminal is used:

curl "http://localhost:591/echo?msg=hello"
 {"msg":["The message is: 'hello'"]}

This API extends the functions in the package. For example, you may query data from the portable database:

curl 'http://127.0.0.1:591/data?table=arrests&where=State%20%3D%20%27California%27%20AND%20Variable%20%3D%20%272017%27&dt=true'
  [
    [
      {"State":"California","Abbrev":"CA","Variable":"2017","Value":"1499","Type":"homicide-arrests","URL":"https://50statespublicsafety.us/app/themes/50state/data/arrests-dashboard/homicide-arrests.csv"},
      {"State":"California","Abbrev":"CA","Variable":"2017","Value":"2561","Type":"rape-arrests","URL":"https://50statespublicsafety.us/app/themes/50state/data/arrests-dashboard/rape-arrests.csv"},{"State":"California","Abbrev":"CA","Variable":"2017","Value":"16942","Type":"robbery-arrests","URL":"https://50statespublicsafety.us/app/themes/50state/data/arrests-dashboard/robbery-arrests.csv"},
      {"State":"California","Abbrev":"CA","Variable":"2017","Value":"88115","Type":"assault-arrests","URL":"https://50statespublicsafety.us/app/themes/50state/data/arrests-dashboard/assault-arrests.csv"},
      {"State":"California","Abbrev":"CA","Variable":"2017","Value":"212025","Type":"drug-arrest","URL":"https://50statespublicsafety.us/app/themes/50state/data/arrests-dashboard/drug-arrest.csv"},
      {"State":"California","Abbrev":"CA","Variable":"2017","Value":"666464","Type":"non-index-arrest","URL":"https://50statespublicsafety.us/app/themes/50state/data/arrests-dashboard/non-index-arrest.csv"}
      ]
    ]

To interact with the API, enable the Swagger interface like so:

ps50sr::launch_api(port = 591, docs = TRUE)

Docker Deployment

For the purposes of encapsulating and deploying the {shiny} app and the {plumber} api, Dockerfiles have been provided under each directory. In order to run these you may need to clone the repo. Again, here a Mac terminal is used:

git clone https://github.com/cjcallag/ps50sr

If you have not, please install Docker.

To deploy the {shiny} app, navigate to the app folder inside the inst folder and build the Docker image with the Dockerfile:

cd inst/ps50sr-dashboard/
docker build -t ps50sr-shinyapp .

Now run the image:

docker run --rm -p 3838:3838 ps50sr-shinyapp

The {plumber} API can be deployed similarly, like so:

cd inst/api/
docker build -t ps50sr-api .
docker run --rm -p 591:591 ps50sr-api