SHARK4R (version 1.1.0)

check_station_distance: Check station distances against SMHI station list

Description

Matches reported station names against the SMHI curated station list ("station.txt") and checks whether matched stations fall within pre-defined distance limits. This helps ensure that station assignments are spatially consistent.

Usage

check_station_distance(
  data,
  station_file = NULL,
  plot_leaflet = FALSE,
  try_synonyms = TRUE,
  fallback_crs = 4326,
  only_bad = FALSE,
  verbose = TRUE
)

Value

If plot_leaflet = FALSE, returns a data frame with columns:

station_name

Reported station name.

match_type

TRUE if station matched in SMHI list, FALSE otherwise.

distance_m

Distance in meters from reported station to matched SMHI station.

within_limit

TRUE if distance <= allowed radius, FALSE if outside, NA if unmatched.

If plot_leaflet = TRUE, the function produces a leaflet map showing:

• Blue circles for SMHI stations with radius in the popup.

• Reported stations colored by status: green (within radius), red (outside radius), gray (unmatched).

• If only_bad = TRUE, only the red stations (outside radius) are displayed.

Arguments

data

A data frame containing at least the columns: station_name, sample_longitude_dd, sample_latitude_dd.

station_file

Optional path to a custom station file (tab-delimited). If NULL (default), the function will first attempt to use the NODC_CONFIG environment variable, and if that fails, will use the bundled "station.zip" from the SHARK4R package.

plot_leaflet

Logical; if TRUE, displays a leaflet map with SMHI stations (blue circles with radius in popup) and reported stations (green/red/gray markers). Default is FALSE.

try_synonyms

Logical; if TRUE (default), unmatched station names are also compared against the SYNONYM_NAMES column in the station database.

fallback_crs

Integer; CRS (EPSG code) to use when creating spatial points if no CRS is available. Defaults to 4326 (WGS84). Change this if your coordinates are reported in another CRS (e.g., 3006 for SWEREF99 TM).

only_bad

Logical; if TRUE, the leaflet map will only display stations that are outside the allowed radius (red markers). Default is FALSE.

verbose

Logical. If TRUE, messages will be displayed during execution. Defaults to TRUE.

Details

Optionally, a leaflet map of stations can be plotted. SMHI stations that match the reported data are shown as blue circles, with their allowed radius visualized and displayed in the popup (e.g., "ST1 (Radius: 1000 m)"). Reported stations are shown as markers colored by whether they fall within the radius (green), outside the radius (red), or unmatched (gray).

If try_synonyms = TRUE, the function will attempt a second match using the SYNONYM_NAMES column in the station database, splitting multiple synonyms separated by <or>.

The function first checks if a station file path is provided via the station_file argument. If not, it looks for the NODC_CONFIG environment variable. This variable can point to a folder where the NODC (Swedish National Oceanographic Data Center) configuration and station file are stored, typically including:

• <NODC_CONFIG>/config/station.txt

If NODC_CONFIG is set and the folder exists, the function will use station.txt from that location. Otherwise, it falls back to the bundled station.zip included in the SHARK4R package.

Examples

# \donttest{
# Example data
df <- data.frame(
  station_name = c("ANHOLT E", "BY5 BORNHOLMSDJ", "NEW STATION"),
  sample_longitude_dd = c(12.1, 15.97, 17.5),
  sample_latitude_dd  = c(56.7, 55.25, 58.7)
)

# Check station distance
try(check_station_distance(df, try_synonyms = TRUE, verbose = FALSE))

# Plot bad points in leaflet map
try(map <- check_station_distance(df,
                              plot_leaflet = TRUE,
                              only_bad = TRUE,
                              verbose = FALSE))
# }