## ----include= FALSE-----------------------------------------------------------
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

## ----setup, message= FALSE----------------------------------------------------
library(gtfsrealtime)
library(dplyr)
library(stringr)

## ----read-alerts--------------------------------------------------------------
alerts <- read_gtfsrt_alerts(
  system.file("nyc-service-alerts.pb.bz2", package = "gtfsrealtime"),
  "America/New_York"
)

## ----glimpse-alerts-----------------------------------------------------------
glimpse(alerts)

## ----inspect-alert------------------------------------------------------------
alerts |>
  filter(id == first(id)) |>
  select(id, route_id, stop_id, header_text, description_text)

## ----summarize-alert----------------------------------------------------------
# make sure trip_route_id and route_id always agree if both are specified
stopifnot(with(alerts, all(is.na(route_id) | is.na(trip_route_id) | route_id == trip_route_id)))

# make sure every update has a route id
stopifnot(with(alerts, all(!is.na(route_id) | !is.na(trip_route_id))))

alerts |>
  mutate(route_id = coalesce(route_id, trip_route_id)) |>
  group_by(id) |>
  slice_head(n=1) |>
  ungroup() |>
  count(route_id, sort = TRUE) |>
  head(10)

## ----alert-text---------------------------------------------------------------
 alerts |>
     distinct(id, header_text, description_text) |>
     mutate(
         header_text = str_trunc(header_text, 80),
         description_text = str_trunc(description_text, 120)
     ) |>
     head()