JSON Data and API’s

Pass Times for U.S. State Captials

library(tidyverse)
library(tidyjson)
library(lubridate)

states <- read_table(
  "https://people.sc.fsu.edu/~jburkardt/datasets/states/state_capitals_ll.txt",
  col_names = c("state", "lat", "long")
) |>
  filter(state != "US")

get_datetimes <- function(lat, long, wait = 0.1) {
  Sys.sleep(wait)

  tryCatch(
    {
      start_times <- httr::GET(
        glue::glue(
          "https://api.g7vrd.co.uk/v1/satellite-passes/25544/{lat}/{long}.json"
        ),
        httr::timeout(10)
      )$content |>
        rawToChar() |>
        as.tbl_json() |>
        enter_object("passes") |>
        gather_array() |>
        spread_all() |>
        mutate(start_dt = as_datetime(start)) |>
        filter(!is.na(start_dt)) |>
        arrange(start_dt) |>
        pull(start_dt)

      valid_pass <- \(n)
        if (length(start_times) >= n) start_times[n] else NA_POSIXct_

      tibble(
        pass1 = valid_pass(1),
        pass2 = valid_pass(2),
        pass3 = valid_pass(3),
      )
    },
    error = function(e) {
      warning(glue::glue(
        "Error processing API for ({lat},{long}): {e$message}"
      ))
      tibble(
        pass1 = NA_POSIXct_,
        pass2 = NA_POSIXct_,
        pass3 = NA_POSIXct_
      )
    }
  )
}

result <- bind_cols(states, map2_df(states$lat, states$long, get_datetimes)) |>
  write_csv("space_data.csv")

Mapping the Data

# Load libraries
library(readr)
library(dplyr)
library(lubridate)
library(lutz)
library(purrr)
library(leaflet)

# Read in your ISS pass data CSV
space_data <- read_csv("space_data.csv")

# Clean the data:
#    - Remove rows where all passes are NA
#    - Filter only valid U.S. longitudes (negative)
cleaned_space <- space_data %>%
  filter(!(is.na(pass1) & is.na(pass2) & is.na(pass3))) %>%
  filter(long < 0)

# Assign time zones based on latitude & longitude
cleaned_space <- cleaned_space %>%
  mutate(tz = tz_lookup_coords(lat, long, method = "accurate"))

# Keep only rows with valid Olson time zones
cleaned_space <- cleaned_space %>%
  filter(tz %in% OlsonNames())

# Convert UTC pass times to local time for each state (rowwise using map2)
cleaned_space <- cleaned_space %>%
  mutate(
    pass1_local = as_datetime(unlist(map2(pass1, tz, ~ with_tz(.x, .y)))),
    pass2_local = as_datetime(unlist(map2(pass2, tz, ~ with_tz(.x, .y)))),
    pass3_local = as_datetime(unlist(map2(pass3, tz, ~ with_tz(.x, .y))))
  )


rocket_icon <- makeIcon(
  iconUrl = "rocket.svg",
  iconWidth = 30, # Adjust size as needed
  iconHeight = 30
)

International Space Station Pass Times (Local Time Zones)

# Plot
m <- leaflet(cleaned_space) %>%
  addTiles() %>%
  addMarkers(
    lng = ~long,
    lat = ~lat,
    icon = rocket_icon,

    # Hover label shows next pass in local time
    label = ~ paste0("Next pass: ", format(pass1_local, "%Y-%m-%d %H:%M:%S")),

    # Clickable popup shows all 3 local pass times
    popup = ~ paste0(
      "<b>",
      state,
      "</b><br/>",
      "Pass 1: ",
      format(pass1_local, "%Y-%m-%d %H:%M:%S"),
      "<br/>",
      "Pass 2: ",
      format(pass2_local, "%Y-%m-%d %H:%M:%S"),
      "<br/>",
      "Pass 3: ",
      format(pass3_local, "%Y-%m-%d %H:%M:%S")
    )
  )
m

Drawing the Route of the ISS

library(leaflet.extras2)

ordered_result <- result |>
  filter(!is.na(pass1)) |>
  arrange(pass1)

m |>
  addArrowhead(
    data = ordered_result,
    lat = ~lat,
    lng = ~long,
    color = "red",
    options = arrowheadOptions(
      frequency = "200px",
      size = "10px",
      color = "purple",
      opacity = 1,
      fill = TRUE
    )
  )