Filter rows by real-world coordinate validity

Removes rows where coordinates fall outside valid geographic ranges ([-90, 90] for latitude, [-180, 180] for longitude). Accepts either separate latitude and longitude columns, or a single combined coordinate column. Supports decimal degree, DMS (DDdeg MM'SS''}), and base-60 (\code{DDdeg MM') coordinate formats.

Usage

latlong_filter(
  data,
  latitude = NULL,
  longitude = NULL,
  combined_col = NULL,
  sep = ",",
  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"). Required if combined_col is not provided.

longitude

Optional. Column name of the longitude column, supplied either unquoted (lon) or quoted ("lon"). Required if combined_col is not provided.

combined_col

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"). Required if latitude and longitude are not provided.

sep

Character. Separator used to split combined_col into latitude and longitude parts. Default is ",".

drop_na

Logical. If TRUE, rows with NA in either coordinate are dropped in addition to out-of-range rows. Default is FALSE.

Value

A data frame containing only rows with valid coordinates, with the same columns as data. Removed rows are attached as attr(result, "invalid") for inspection. A console message reports the total number of rows removed.

Details

All coordinate formats are parsed to decimal degrees internally before range validation. The parser handles decimal, DMS, and base-60 formats, inferring sign from cardinal direction suffixes (S, W) or the sign of the degree value. Zero-width and BOM characters are stripped before parsing.

Either combined_col or both latitude and longitude must be provided; supplying neither raises an error. When drop_na = FALSE (the default), rows with NA coordinates are still removed as they cannot pass range validation, and are captured in attr(result, "invalid").

Use latlong_format to check coordinate formats before filtering, and latlong_column to identify coordinate columns if their names are not known in advance.

See also

latlong_format for checking coordinate formats before filtering,

latlong_column for detecting coordinate columns in a data frame,

latlong_convert for converting DMS or base-60 columns to decimal degrees before filtering,

latlong_range for filtering rows to a user-defined bounding box,

latlong_region for filtering rows to named geographic regions.

Examples

df <- data.frame(
  id  = 1:5,
  lat = c(51.5, 48.8, 91.0, -33.9, NA),
  lon = c(-0.1, 2.3, 139.7, 151.2, 37.6)
)

# Filter using separate latitude and longitude columns
latlong_filter(df, latitude = lat, longitude = lon)
#> [latlong_filter] 2 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
#> 4  4 -33.9 151.2

# Inspect rows that were removed
result <- latlong_filter(df, latitude = lat, longitude = lon)
#> [latlong_filter] 2 row(s) removed with invalid or out-of-range coordinates
attr(result, "invalid")
#>   id lat   lon
#> 3  3  91 139.7
#> 5  5  NA  37.6

# Also drop rows where either coordinate is NA
latlong_filter(df, latitude = lat, longitude = lon, drop_na = TRUE)
#> [latlong_filter] 2 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
#> 4  4 -33.9 151.2

# Filter using a combined coordinate column
df_combined <- data.frame(
  id     = 1:4,
  coords = c("51.5,-0.1", "91.0,2.3", "-33.9,151.2", "48.8,181.0")
)
latlong_filter(df_combined, combined_col = coords)
#> [latlong_filter] 2 row(s) removed with invalid or out-of-range coordinates
#>   id      coords
#> 1  1   51.5,-0.1
#> 3  3 -33.9,151.2

# Combined column with a custom separator
df_sep <- data.frame(
  coords = c("51.5;-0.1", "91.0;2.3", "-33.9;151.2")
)
latlong_filter(df_sep, combined_col = coords, sep = ";")
#> [latlong_filter] 1 row(s) removed with invalid or out-of-range coordinates
#>        coords
#> 1   51.5;-0.1
#> 3 -33.9;151.2