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Report coordinate limits of a data frame

Source: R/latlong_limits.R
latlong_limits.Rd

Identifies and reports the minimum and maximum latitude and longitude values in a data frame. Accepts separate latitude and longitude columns, a combined coordinate column, or auto-detects coordinate columns using latlong_column when no columns are specified. Prints a summary message and returns the data frame unchanged, making it safe to use mid-pipeline.

Usage

latlong_limits(
  data,
  latitude = NULL,
  longitude = NULL,
  column = NULL,
  drop_na = FALSE
)

Arguments

data

A data frame containing coordinate columns.

latitude

Optional. Column name of the latitude column, supplied either unquoted (lat) or quoted ("lat").

longitude

Optional. Column name of the longitude column, supplied either unquoted (lon) or quoted ("lon").

column

Optional. Column name of a combined coordinate column containing latitude and longitude as a single delimited string (e.g. "51.5,-0.1"), supplied either unquoted (coords) or quoted ("coords"). Supports ",", ";", and whitespace as delimiters.

drop_na

Logical. If TRUE, rows with NA coordinate values are excluded from the limit calculation. Default is FALSE.

Value

The original data frame, returned invisibly and unchanged. This function is called for its side effect of printing latitude and longitude range messages to the console, and is safe to use within a pipeline (e.g. with |>) without altering the data.

Details

When none of latitude, longitude, or column are provided, coordinate columns are auto-detected via latlong_column. The first detected latitude, longitude, and combined column are used. An error is raised if no coordinate columns are found.

Values outside valid geographic ranges ([-90, 90] for latitude, [-180, 180] for longitude) are silently excluded from the limit calculation. Use latlong_filter to remove such rows from the data frame explicitly.

Combined columns are split on ",", ";", or whitespace before parsing. Only numeric (decimal degree) values are extracted from combined columns; DMS and base-60 formats in combined columns are not parsed. Use latlong_convert to convert to decimal degrees first if needed.

See also

latlong_column for detecting coordinate columns automatically,

latlong_filter for removing out-of-range coordinates,

latlong_range for filtering rows to a user-defined bounding box using the limits reported by this function,

latlong_convert for converting DMS or base-60 columns to decimal before computing limits.

Examples

df <- data.frame(
  id  = 1:4,
  lat = c(51.5, 48.8, -33.9, 40.7),
  lon = c(-0.1, 2.3, 151.2, -74.0)
)

# Report limits from separate latitude and longitude columns
latlong_limits(df, latitude = lat, longitude = lon)
#> [latlong_limits] latitude  — min: -33.900000, max: 51.500000
#> [latlong_limits] longitude — min: -74.000000, max: 151.200000

# Auto-detect coordinate columns
latlong_limits(df)
#> [latlong_limits] latitude  — min: 1.000000, max: 4.000000
#> [latlong_limits] longitude — min: -74.000000, max: 151.200000

# Report limits from a combined coordinate column
df_combined <- data.frame(
  coords = c("51.5,-0.1", "48.8,2.3", "-33.9,151.2", "40.7,-74.0")
)
latlong_limits(df_combined, column = coords)
#> [latlong_limits] latitude  — min: -33.900000, max: 51.500000
#> [latlong_limits] longitude — min: -74.000000, max: 151.200000

# Exclude NA values from the limit calculation
df_na <- data.frame(
  lat = c(51.5, NA, -33.9, 40.7),
  lon = c(-0.1, 2.3, 151.2, NA)
)
latlong_limits(df_na, latitude = lat, longitude = lon, drop_na = TRUE)
#> [latlong_limits] latitude  — min: -33.900000, max: 51.500000
#> [latlong_limits] longitude — min: -0.100000, max: 151.200000

# Safe to use mid-pipeline — data is returned unchanged
df |>
  latlong_limits(latitude = lat, longitude = lon) |>
  latlong_filter(latitude = lat, longitude = lon)
#> [latlong_limits] latitude  — min: -33.900000, max: 51.500000
#> [latlong_limits] longitude — min: -74.000000, max: 151.200000
#> [latlong_filter] 0 row(s) removed with invalid or out-of-range coordinates
#>   id   lat   lon
#> 1  1  51.5  -0.1
#> 2  2  48.8   2.3
#> 3  3 -33.9 151.2
#> 4  4  40.7 -74.0